Electrostatic protection circuits and electronic equipment

Abstract

The present application provides an electrostatic protection circuit and an electronic device, wherein the electrostatic protection circuit is arranged on a signal line between an input / output interface connecting an electronic device and a protected component, and the electrostatic protection circuit comprises: a first electrostatic protector, wherein the first end of the first electrostatic protector is connected to the input / output interface, and the first end of the first electrostatic protector is also connected to the protected component; the second end of the first electrostatic protector is connected to the first end of a first capacitor, and the second end of the first capacitor is grounded. When the present application is in use, most of the high-voltage static electricity is stored in the first capacitor after breaking through the first electrostatic protector, and becomes low-voltage power supply energy, thereby reducing the amount of static electricity flowing to the protected component, which is beneficial to increasing the service life of the electronic device.

Description

Technical Field

[0001] The present application relates to electrostatic protection technology, and in particular to an electrostatic protection circuit and electronic equipment. Background Art

[0002] Static electricity is a static charge or a non-flowing charge. In daily life, the human body often carries static electricity. When the human body touches an electronic device, static electricity flows from the human body to the electronic device, causing static discharge, which may affect the normal operation of the electronic device, and in severe cases, even cause the chips and other components in the electronic device to break down, resulting in irreparable losses.

[0003] Electronic devices all have complete shells, and the impact of static electricity on the internal components of electronic devices is generally realized through the external interfaces on the electronic devices. For example, when designing electronic devices, it is often encountered that the input / output (I / O) interface is exposed outside the shell. For example, the USB (Universal Serial Bus) interface must protrude from the shell for data transmission and charging and power supply needs; the headphone interface needs to be exposed to connect to external headphones for outputting music. When encountering electrostatic discharge, static electricity will enter the interior of the electronic device through these input / output interfaces, which may damage the components inside the electronic device and cause permanent damage.

[0004] Therefore, it is necessary to design a special electrostatic protection circuit to reduce the impact of electrostatic discharge on electronic equipment. Summary of the invention

[0005] The purpose of the present application is to provide an electrostatic protection circuit and an electronic device, which can reduce the impact of electrostatic discharge on the electronic device and help to increase the service life of the electronic device.

[0006] On the one hand, the present application provides an electrostatic protection circuit, which is arranged on a signal line between an input / output interface of an electronic device and a protected component, and the electrostatic protection circuit includes: a first electrostatic protector, a first end of the first electrostatic protector is connected to the input / output interface, and the first end of the first electrostatic protector is also connected to the protected component; the second end of the first electrostatic protector is connected to the first end of a first capacitor, and the second end of the first capacitor is grounded.

[0007] When the present application is in use, most of the high-voltage static electricity breaks through the first static protector and is stored in the first capacitor, becoming low-voltage power energy, thereby reducing the amount of static electricity flowing to the protected components, which is beneficial to increasing the service life of the electronic device.

[0008] As the electrostatic protection circuit described above, optionally, the first electrostatic protector includes one or more of an ESD electrostatic diode, a TVS diode, a switching diode, a TSS diode, a voltage regulator diode, a varistor, and a gas discharge tube.

[0009] As described above, in the electrostatic protection circuit, optionally, a first electronic component is also connected in series between the protected component and the input / output interface, wherein the first end of the first electronic component is connected to the input / output interface, and the second end of the first electronic component is connected to the protected component; and the first end of the first electrostatic protector is connected between the input / output interface and the first end of the first electronic component.

[0010] In the electrostatic protection circuit as described above, optionally, the first electronic component includes a magnetic bead, an inductor and / or a resistor.

[0011] In the electrostatic protection circuit as described above, optionally, the first end of the first capacitor is also connected to the first end of the power-consuming element, and the second end of the power-consuming element is grounded.

[0012] In the electrostatic protection circuit as described above, optionally, the power consumption element includes a second resistor, and the resistance of the second resistor is greater than 20 kΩ.

[0013] As for the electrostatic protection circuit as described above, optionally, a second capacitor is connected in series between the second end of the first electronic component and the protected component, the first end of the second capacitor is connected to the protected component, and the second end of the second capacitor is connected to the second end of the first electronic component.

[0014] As for the electrostatic protection circuit as described above, optionally, a first resistor is also connected in series between the first end of the second capacitor and the protected component, the first end of the first resistor is connected to the protected component, and the second end of the first resistor is connected to the first end of the second capacitor.

[0015] As for the electrostatic protection circuit as described above, optionally, a second electrostatic protector is further provided between the first electronic component and the second capacitor, the third end of the second electrostatic protector is connected between the first electronic component and the second capacitor, and the first end of the second electrostatic protector is grounded.

[0016] As described above, the electrostatic protection circuit, optionally, the electronic device is further provided with a power supply circuit, the power supply circuit comprising a power supply input terminal and a power supply output terminal;

[0017] The second electrostatic protector is a triangular tube protector, the second electrostatic protector includes a first diode and a second diode, the cathode of the first diode is connected to the anode of the second diode, the anode of the first diode is grounded through the first end of the second electrostatic protector, the cathode of the second diode is connected to the power input end or the power output end through the second end of the second electrostatic protector, the third end of the second electrostatic protector is arranged between the cathode of the first diode and the anode of the second diode, and the third end of the second electrostatic protector is connected to the second end of the first electronic component;

[0018] Alternatively, the second electrostatic protector includes a third diode and a fourth diode, the cathode of the third diode is connected to the anode of the fourth diode, the anode of the third diode is grounded through the first end of the second electrostatic protector, the cathode of the fourth diode is connected to the power input end or the power output end through the second end of the second electrostatic protector, the third end of the second electrostatic protector is arranged between the cathode of the third diode and the anode of the fourth diode, and the third end of the second electrostatic protector is connected to the second end of the first electronic component.

[0019] As described above, the electrostatic protection circuit, optionally, the electronic device has a built-in battery, the battery includes a positive electrode and a negative electrode, and the negative electrode of the battery is grounded;

[0020] The second electrostatic protector is a triangular tube protector, the second electrostatic protector includes a first diode and a second diode, the cathode of the first diode is connected to the anode of the second diode, the anode of the first diode is grounded through the first end of the second electrostatic protector, the cathode of the second diode is connected to the positive electrode of the battery through the second end of the second electrostatic protector, the third end of the second electrostatic protector is arranged between the cathode of the first diode and the anode of the second diode, and the third end of the second electrostatic protector is connected to the second end of the first electronic component;

[0021] Alternatively, the second electrostatic protector includes a third diode and a fourth diode, the cathode of the third diode is connected to the anode of the fourth diode, the anode of the third diode is grounded through the first end of the second electrostatic protector, the cathode of the fourth diode is connected to the positive electrode of the battery through the second end of the second electrostatic protector, the third end of the second electrostatic protector is arranged between the cathode of the third diode and the anode of the fourth diode, and the third end of the second electrostatic protector is connected to the second end of the first electronic component.

[0022] As described above, the electrostatic protection circuit, optionally, the second electrostatic protector is a triangular tube protector, the second electrostatic protector includes a first diode and a second diode, the cathode of the first diode is connected to the anode of the second diode, the anode of the first diode is grounded through the first end of the second electrostatic protector, the cathode of the second diode is grounded through the second end of the second electrostatic protector, the third end of the second electrostatic protector is arranged between the cathode of the first diode and the anode of the second diode, and the third end of the second electrostatic protector is connected to the second end of the first electronic component;

[0023] Alternatively, the second electrostatic protector includes a third diode and a fourth diode, the cathode of the third diode is connected to the anode of the fourth diode, the anode of the third diode is grounded through the first end of the second electrostatic protector, the cathode of the fourth diode is grounded through the second end of the second electrostatic protector, the third end of the second electrostatic protector is arranged between the cathode of the third diode and the anode of the fourth diode, and the third end of the second electrostatic protector is connected to the second end of the first electronic component.

[0024] In the electrostatic protection circuit as described above, optionally, the second end of the second electrostatic protector is also connected to the first end of a third capacitor, and the second end of the third capacitor is grounded.

[0025] In the electrostatic protection circuit as described above, optionally, the power supply voltage of the electronic device is connected between the second end of the second electrostatic protector and the first end of the third capacitor.

[0026] As described above, the electrostatic protection circuit, optionally, the power-consuming element also includes a power supply of the electronic device, the first end of the power supply is connected between the second end of the second electrostatic protector and the first end of the third capacitor, and the second end of the power supply is grounded; the first end of the first capacitor is connected to the first end of the power supply via at least one fifth diode.

[0027] As for the electrostatic protection circuit as described above, optionally, a metal sheet is further provided between the second end of the third capacitor and the ground line.

[0028] In the electrostatic protection circuit as described above, optionally, the inductor includes a differential mode inductor or a common mode inductor.

[0029] In the electrostatic protection circuit as described above, optionally, the first capacitor includes at least two capacitors whose impedance characteristic curves are located at different resonance points, and the resonance point of each capacitor corresponds to a different interference frequency point of electrostatic discharge or air discharge.

[0030] On the other hand, the present application provides an electronic device, including a shielding shell, a protected component is provided inside the shielding shell, and an input / output interface is also provided outside the shielding shell, the input / output interface is connected to the protected component through a signal line, and the signal line is provided with any of the above-described electrostatic protection circuits.

[0031] Since the electronic device of the present application is provided with the above-mentioned electrostatic protection circuit, when encountering electrostatic discharge, the static electricity has less impact on the components in the electronic device, which is beneficial to improving the service life of the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the following is a brief introduction to the drawings required for use in the embodiments or the related technical descriptions. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 It is a simplified structural diagram of an electronic device in the related art;

[0034] Figure 2 It is a simplified structural diagram of another electronic device in the related art;

[0035] Figure 3 It is the electrostatic discharge current waveform;

[0036] Figure 4 A discharge model for electrostatic discharge equipment;

[0037] Figure 5 A top view of a PCB layout in a battery-powered device;

[0038] Figure 6 It is an electrical model of the components on the PCB board in a battery-powered device;

[0039] Figure 7 A schematic diagram of an electrostatic protection circuit provided in one embodiment of the present application;

[0040] Figure 8 A schematic diagram of an electrostatic protection circuit provided in another embodiment of the present application;

[0041] Fig. 9 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0042] Fig.10 The characteristic curve diagram of the impedance frequency of the magnetic beads in one embodiment of the present application;

[0043] Fig.11 for Fig.40 The corresponding PCB board layout and wiring diagram;

[0044] Fig.12 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0045] Fig.13 is the equivalent model of capacitor;

[0046] Figure 14-Figure 20 The impedance frequency curve of ceramic capacitors with different capacitance values;

[0047] Fig.21 This is the impedance frequency curve of 150μF tantalum capacitor;

[0048] Fig. 22 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0049] Fig.23 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0050] Fig.24 The frequency characteristic curve of the inductance of the coaxial cable power supply;

[0051] Fig.25 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0052] Fig.26 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0053] Fig. 27 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0054] Fig.28 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0055] Fig.29 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0056] Fig.30 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0057] Fig.31 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0058] Fig.32 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0059] Fig.33 for Fig.32 A partial cross-sectional view of

[0060] Fig.34 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0061] Fig.35 for Fig.34 A partial cross-sectional view of

[0062] Fig.36 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application;

[0063] Fig.37 A top view of a PCB ground line provided in one embodiment of the present application;

[0064] Fig.38 A top view of a PCB ground copper foil provided in one embodiment of the present application;

[0065] Fig.39 A top view of a PCB ground copper foil provided in another embodiment of the present application;

[0066] Fig.40 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0068] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0069] When the human body touches an electronic device, electrostatic discharge may affect the normal operation of the electronic device. In severe cases, it may even cause the chips and other components in the electronic device to break down, resulting in irreparable losses. Figure 1 This is a simplified structural diagram of an electronic device in the related art. Figure 1 The electronic device includes a housing 63 and a PCB board 61 disposed in the housing 63. A notch 60 is disposed on an end surface 65 of the housing 63. A USB interface 62 is installed in the notch 60. The USB interface 62 is connected to the PCB board 61 and is used to connect the PCB board 61 to an external power supply. Figure 1 In the electronic device shown, the USB interface 62 is arranged to protrude from the housing 63 , that is, a portion of the USB interface 62 is located outside the end surface 65 , so as to facilitate the external power adapter terminal (not shown in the figure) to pass through the gap 60 and connect to the USB interface 62 . Figure 2The figure is a simplified structural diagram of another electronic device in the related art. Figure 2 The electronic equipment shown is Figure 1 The electronics shown differ in that Figure 2 In the electronic device shown, the USB interface 62 is flush with the end surface 65 of the housing 63. Figure 1 Electronic devices, or Figure 2 In electronic devices, fingers can touch the USB interface 62, thus generating electrostatic discharge. When electrostatic discharge is injected into the input / output interface of the product by contact discharge, the product will be subjected to instantaneous high-voltage electrostatic energy, especially the interface part, which can easily cause the product to freeze, reset, make a squeaking sound from the speaker, and other functional abnormalities, and even damage the internal chip of the product, resulting in the product not being able to start normally.

[0070] In order to reduce the impact of electrostatic discharge on the daily use of electronic equipment, China's G6.2B / T1762 standard (equivalent to the international standard IEC61000-4-2) requires that all metal parts of the interface on the casing of the electronic device that can be clearly touched by fingers need to be contact discharged. Figure 3 The figure shows the electrostatic discharge current waveform required by the Chinese G6.2B / T1762 standard; Table 1 gives the discharge current values ​​of different levels of contact discharge tests at different time periods.

[0071] Table 1 Discharge current values ​​of different levels of contact discharge test at different time periods

[0072]

[0073] Combination Figure 3As shown in Table 1, under the 2kV level contact discharge test conditions: within the discharge current rise time of 0.6ns to 1ns, the discharge current reaches 7.5A; when the discharge current is 30ns, the discharge current reaches 4A; when the discharge current is 60ns, the discharge current reaches 2A. Under the 4kV level contact discharge test conditions: within the discharge current rise time of 0.6ns to 1ns, the discharge current reaches 15A; when the discharge current is 30ns, the discharge current reaches 8A; when the discharge current is 60ns, the discharge current reaches 4A. Under the 6kV level contact discharge test conditions: within the discharge current rise time of 0.6ns to 1ns, the discharge current reaches 22.5A; when the discharge current is 30ns, the discharge current reaches 12A; when the discharge current is 60ns, the discharge current reaches 6A. Under the 8kV level contact discharge test conditions: within the discharge current rise time of 0.6ns to 1ns, the discharge current reaches 30A; when the discharge current is 30ns, the discharge current reaches 16A; when the discharge current is 60ns, the discharge current reaches 8A. In other words, the higher the contact discharge test level, the greater the discharge current generated by the test, which is almost proportional, bringing huge challenges to the electrostatic protection design of electronic equipment. The specifications of the contact discharge test vary according to different product types. For example, the contact discharge of the USB interface of the set-top box needs to be 4kV; the contact discharge of the power interface and USB interface of the industrial router needs to be 8kV; the contact discharge of the input / output interface of the vehicle-mounted device 802 needs to be 8kV; the contact discharge of the headphone interface and USB interface of the fetal heart monitor needs to be 6kV; the contact discharge of the fingerprint button of the mobile phone needs to be 12kV.

[0074] Combination Figure 3 From Table 1, we can see that the minimum discharge period of contact discharge is 0.6ns. The conversion formula between period T and frequency f is as follows:

[0075] T = 1 / f,

[0076] Then f = 1 / T = 1 / 0.6x10 -9 s≈1.667x10 9 Hz=1.667GHz, which means the highest frequency band of static electricity interference is about 1.667GHz.

[0077] The discharge period of contact discharge is 1ns, and the conversion formula between period T and frequency f is as follows:

[0078] T = 1 / f,

[0079] Then f=1 / T=1 / 1x10 -9 s=1.0x10 9 Hz=1GHz, which means the interference frequency band of static electricity is 1GHz.

[0080] The discharge period of contact discharge is 30ns. The conversion formula of period T and frequency f is as follows:

[0081] T = 1 / f,

[0082] Then f=1 / T=1 / 30x10 -9 s≈0.033333x10 9 Hz=0.033333GHz=33.33MHz, which means that the interference frequency band of static electricity is about 33.33MHz.

[0083] The discharge period of contact discharge is 60ns, and the conversion formula of period T and frequency f is as follows:

[0084] T = 1 / f,

[0085] Then f=1 / T=1 / 60x10 -9 s≈0.01667x10 9 Hz=0.01667GHz=16.67MHz, which means that the interference frequency band of static electricity is about 16.67MHz.

[0086] Figure 4 This is the discharge model for electrostatic discharge equipment. Please refer to Figure 4 The specifications of the electrostatic discharge device are as follows: Uo is the DC high-voltage power supply of the electrostatic discharge device, Rc is the internal resistance of the DC high-voltage power supply (about 50 megohms to 100 megohms), the discharge capacitor Cs is 150pF, the internal resistance Rd is 330 ohms (330 ohms represents the human body resistance of the human body holding keys and other metal tools), K1 is the switch of the electrostatic discharge device, M1 is the discharge head of the electrostatic discharge device, and M2 is the connection point of the discharge circuit. The relevant standards believe that it is harsh enough to use this discharge model (including capacitance and resistance values) to describe electrostatic discharge.

[0087] Figure 5 A top view of a PCB layout in a battery-powered device; Figure 6 It is an electrical model of the components on the PCB board in a battery-powered device.

[0088] Since the internal electrode surface of the battery in a battery-powered device is limited, the battery and PCB board have limited ability to absorb high-voltage static electricity. Figure 5As shown, the USB connector 16 is provided with a first metal contact 10 (USB+) and a second metal contact 11 (USB-), and a USB differential trace 17 is led out from the two metal contacts of the USB connector 16, and the USB differential trace 17 is respectively connected to the PCB ground copper foil G in parallel with the electrostatic protector 12 and the electrostatic protector 13. In other words, one end of the electrostatic protector 12 is electrically connected to the USB+ of the USB differential trace 17, and the other end is electrically connected to the ground copper foil G through a ground via 504 (referring to N ground vias, N≧1) (the ground copper foil G includes the surface ground copper foil and the inner ground copper foil), and then electrically connected to the negative electrode of the battery 132 through the ground copper foil G and the negative electrode of the battery connector 134. One end of the electrostatic protector 13 is electrically connected to the USB- of the USB differential trace 17, and the other end is electrically connected to the ground copper foil G through the ground via 504 (referring to N ground vias, N≧1) (the ground copper foil G includes the surface ground copper foil and the inner ground copper foil), and then electrically connected to the negative electrode of the battery 132 through the ground copper foil G and the negative electrode of the battery connector 134. When a contact discharge of 4kV to 12kV is injected between the first metal contact 10 and the second metal contact 11, 4kV to 12kV of static electricity will be generated in the USB differential trace 17, and the electrostatic protectors 12 and 13 connected in parallel at both ends of the USB differential trace 17 will be instantly broken down and turned on, clamping the 4kV to 12kV static electricity to about ten volts. However, there is still a residual voltage of more than ten volts discharged to the baseband chip 55, and the USB pin of the baseband chip 55 will appear garbled, which may cause problems with the USB eye diagram (the eye diagram is an indicator of the quality of the USB differential).

[0089] In addition, if the battery-powered device discharges static electricity directly to the copper foil G of the PCB, the copper foil G of the PCB will generate a discharge current due to static electricity. Figure 5As shown, the memory (DDR) particle 56 is electrically connected to the ground copper foil G (the ground copper foil G includes the surface ground copper foil and the inner ground copper foil) through the ground via 501 (referring to N ground vias, N≧1); and then electrically connected to the negative electrode of the battery 132 through the ground copper foil G and the negative electrode of the battery connector 134. The baseband chip 55 is electrically connected to the ground copper foil G (the ground copper foil G includes the surface ground copper foil and the inner ground copper foil) through the ground via 502 (referring to N ground vias, N≧1); and then electrically connected to the negative electrode of the battery 132 through the PCB ground copper foil G and the negative electrode of the battery connector 134. The flash memory chip 54 is electrically connected to the ground copper foil G (the ground copper foil G includes the surface ground copper foil and the inner ground copper foil) through the ground via ≦5 (referring to N ground vias, N≧1); and then electrically connected to the negative electrode of the battery 132 through the ground copper foil G and the negative electrode of the battery connector 134. The RF chip 57 is electrically connected to the ground copper foil G (the ground copper foil G includes the surface ground copper foil and the inner ground copper foil) through the ground via 503 (referring to N ground vias, N≧1); and then electrically connected to the negative electrode of the battery 132 through the ground copper foil G and the negative electrode of the battery connector 134. The baseband chip 55 is electrically connected to the memory particle 56 through the memory line 51 (sensitive signal line), the baseband chip 55 is electrically connected to the flash memory chip 54 through the serial peripheral interface (SPI) line 513 (sensitive signal line), and the baseband chip 55 is electrically connected to the RF chip 57 through the IQ line 512 (sensitive signal line).

[0090] The discharge current generated by static electricity on the ground copper foil G at the position of the baseband chip 55 is i2, and the electrical impedance between the baseband chip 55 through the ground via 502, the ground copper foil G and the negative electrode of the battery is approximately R12. Therefore, the voltage drop between the baseband chip 55, the ground copper foil G and the negative electrode of the battery is V6 (V6=R12×i2).

[0091] The discharge current generated by static electricity on the ground copper foil G at the location of the memory particle 56 is i1, and the electrical impedance between the memory particle 56 through the ground via 501, the ground copper foil G and the negative electrode of the battery is approximately R13. Therefore, the voltage drop between the memory particle 56, the ground copper foil G and the negative electrode of the battery is V7 (V7=R13×i1).

[0092] The discharge current generated by static electricity from the ground via 502 through the ground copper foil G to the ground via 501 is i11, and the electrical impedance from the ground via 502 through the ground copper foil G to the ground via 501 is approximately R21. Therefore, the voltage drop generated by static electricity from the ground via 502 through the ground copper foil G to the ground via 501 is V2 (V2=R21×i11).

[0093] During normal operation, the memory chip 56 and the baseband chip 55 are connected by signal through the memory wiring 51. The reference point of the memory chip 56 is the ground via 501, and the reference point of the baseband chip 55 is the ground via 502. The ground via 501 and the ground via 502 are electrically connected through the ground copper foil G. Since the wiring current of the memory wiring 51 is very small, the return current from the ground via 502 to the ground via 501 is small, and the voltage drop between them is very small; that is, the potential of the reference point of the baseband chip 55 is almost equal to the potential of the reference point of the memory chip 56. However, when static electricity is injected into the USB connector, the static electricity instantly generates a huge pulse current, which will cause the potential difference between the reference point of the baseband chip 55 and the reference point of the memory chip 56 to be very large (the potential difference between the reference point of the baseband chip 55 and the reference point of the memory chip 56 is V2, and V2 is equal to the absolute value of V7-V6). At this time, the communication between the baseband chip 55 and the memory particle 56 will produce garbled characters (such as packet loss, system crash, etc.), which may damage the device in serious cases.

[0094] The discharge current generated by static electricity on the ground copper foil G at the location of the flash memory chip 54 is i3, and the electrical impedance between the flash memory chip 54 through the ground via 505, the ground copper foil G and the negative electrode of the battery is approximately R14. Therefore, the voltage drop between the flash memory chip 54, the ground copper foil G and the negative electrode of the battery is V8 (V6=R14×i3).

[0095] The discharge current i4 generated by static electricity on the ground copper foil G at the position of the RF chip 57, the electrical impedance between the RF chip 57 through the ground via 503, the ground copper foil G and the negative electrode of the battery is approximately R15, so the voltage drop between the RF chip 57, the ground copper foil G and the negative electrode of the battery is V9 (V9=R15×i4).

[0096] After long-term research, the inventors of the present application have summarized the following principles for electrostatic protection of electronic devices: 1. Block static electricity in the outer shell as much as possible (the metal shell connected to the PCB ground copper foil G can conduct static electricity to the ground; for plastic shells, block static electricity outside the plastic shell to prevent it from being discharged to internal components). 2. Do not expose the input / output interface as much as possible, and use air discharge if non-contact discharge is possible, as air discharge is less harmful than contact discharge. 3. For AC-DC (alternating current-direct current) power supply equipment, if it can be discharged to the PCB ground copper foil G, try to discharge it to the PCB ground copper foil G instead of on the signal line; static electricity discharged on the signal line should be conducted to the PCB ground copper foil G or the power supply in the PCB board using an electrostatic protector to avoid damaging components or causing input / output pins to fail. 4. For battery-powered devices, if the exposed input / output interface cannot be sealed, try to discharge the static electricity of the input / output interface to the capacitor (such as electrolytic capacitor, supercapacitor), and store the high-voltage static electricity on the two plates of the capacitor. This can greatly reduce the electromotive force of the static charge, greatly weaken the impact of the static charge on the input / output interface signal, and prevent the level of the surrounding PCB ground copper foil G from being raised, causing the PCB ground copper foil G to discharge static electricity to other input / output interfaces, causing other input / output interface signal reset or damage to the input / output interface and a series of abnormal problems.

[0097] Based on the above, the present application aims to provide an electrostatic protection circuit and an electronic device, by connecting a first electrostatic protector between an input / output interface and a first electronic component, and connecting a first capacitor C1 in series between the first electrostatic protector and a PCB ground copper foil or a PCB ground wire; after high-voltage static electricity flows in from the input / output interface, most of the high-voltage static electricity breaks through the first electrostatic protector and is stored in the first capacitor C1, becoming low-voltage power supply energy, thereby reducing the amount of static electricity flowing to the protected component, which is beneficial to improving the service life of the electronic device.

[0098] The width of the PCB ground wire 23 is less than 0.8 mm, and the shape of the PCB ground copper foil 23 can be a regular pattern or an irregular pattern, and the PCB ground wire 23 is generally regular and has a uniform width.

[0099] Fig.37 A top view of a PCB ground line provided in one embodiment of the present application; Fig.38 A top view of a PCB ground copper foil provided in one embodiment of the present application; Fig.39 This is a top view of a PCB ground copper foil provided by another embodiment of the present application. Please refer to Figure 37-Figure 39 ,in Fig.38 A top view of the copper foil of a regular pattern PCB is given; Fig.39A top view of the irregular pattern PCB ground copper foil is given. It should be noted that the PCB ground copper foil 23 has the same function as the PCB ground wire 23, except that the width of the PCB ground copper foil 23 is larger than the width of the PCB ground wire 23: PCB ground wire 23 < 1mm, the width W1 of the PCB ground copper foil 23 ≧ 1mm. In addition, the line width of the PCB ground wire 23 is fixed, for example, the line width W1 of a ground wire is 0.8mm or 0.9mm. Fig.37 In order to bypass the signal via 901, the ground wire 23 has a bend 903. The shape of the ground wire 23 is not limited. The shape of the PCB ground copper foil 23 can be a regular pattern, such as Fig.38 The shape of the PCB ground copper foil 23 is a regular rectangle, the width W1 of the PCB ground copper foil 23 is ≧1 mm, and a plurality of ground holes 900 are distributed in the PCB ground copper foil 23. The shape of the PCB ground copper foil 23 can also be an irregular pattern, for example Fig.39 The shape of the PCB ground copper foil 23 is a regular pattern, and there is a slot 905 below the PCB ground copper foil 23. At the same time, the PCB ground copper foil 23 can also have a ground hole 900, a power via 903, and a signal via 901. In order to avoid short circuits between the power via 903 and the signal via 901 in the PCB ground copper foil 23, a clearance area 904 (copper-free area) is set between the PCB ground copper foil 23 and the power via 903, and a clearance area 906 (copper-free area) is set between the PCB ground copper foil 23 and the signal via 901. That is, Fig.39 The ground copper foil 23 has slots 905, clearance areas 906, clearance areas 904, etc. The ground copper foil 23 is an irregular pattern.

[0100] It should be noted that the protected component 200 can be either a protected component (such as an MCU, a baseband chip, etc.) or a protected module composed of a protected component and its peripheral circuits, because some protected components can be directly connected to the Figure 7 to Figure 9 , Fig.11 , Fig.12 , Fig. 22 , Fig.23 , Figure 25 to Figure 32 After the circuit protection scheme shown is connected, it is then connected to the input / output interface 100. For example, the pin lead signal line of the MCU common I / O can be connected through Figure 7 to Figure 9 , Fig.11 , Fig.12 , Fig. 22 , Fig.23 , Figure 25 to Figure 32 After the circuit protection scheme is connected, it is connected to the input / output interface 100 (such as a reset signal). This scheme is defined as a protected component, which is also a type of protected component 200. Some protected components need to add some resistance-capacitance matching circuits to be connected. Figure 7 to Figure 9 , Fig.11 , Fig.12 , Fig. 22 , Fig.23 , Figure 25 to Figure 32 The circuit protection scheme shown is connected to the input / output interface 100: for example, an audio codec ( C oder-DECoder, video and audio compression and decompression codec) chip to lead out the MIC (microphone) circuit needs to add some MIC audio resistance and capacitance matching circuit, and the resistance and capacitance matching circuit is then connected to the signal line through the signal line. Figure 7 to Figure 9 , Fig.11 , Fig.12 , Fig. 22 , Fig.23 , Figure 25 to Figure 32 After one of the circuit protection schemes shown is connected, it is connected to the MIC (belonging to the input / output interface 100); after the Wifi chip leads to the balun circuit to synthesize the differential RF signal into a single RF signal, a 50-ohm matching circuit needs to be added, and the 50-ohm matching circuit is then connected to the MIC through the signal line. Figure 7 to Figure 9 , Fig.11 , Fig.12 , Fig. 22 , Fig.23 , Figure 25 to Figure 32 The circuit protection scheme shown is connected to one of the external antennas (belonging to the input / output interface 100). The Wifi chip cannot be directly connected to the external antenna through the signal line. Figure 7 to Figure 9 , Fig.11 , Fig.12 , Fig. 22 , Fig.23 , Figure 25 to Figure 32 After one of the circuit protection schemes shown is connected, it is connected to an external antenna (belonging to the input / output interface 100). The audio codec chip + MIC audio resistance-capacitance matching circuit is defined as a protected module, which is also a type of protected component 200. The Wifi (Wireless Fidelity) chip + balun circuit + 50 ohm matching circuit is defined as a protected module, which is also a type of protected component 200.

[0101] The contents of the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings so that those skilled in the art can understand the contents of the present application in more detail.

[0102] Figure 7 A schematic diagram of an electrostatic protection circuit provided in one embodiment of the present application; Figure 8 A schematic diagram of an electrostatic protection circuit provided in another embodiment of the present application; Fig. 9 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application.

[0103] Please refer to Figure 7-Figure 9 , this embodiment provides an electrostatic protection circuit, which is used to be set on a signal line 300 between an input / output interface 100 and a protected component 200 connected to an electronic device. The electrostatic protection circuit includes a first electrostatic protector VD1, a first end of the first electrostatic protector VD1 is connected to the input / output interface 100, and the first end of the first electrostatic protector VD1 is also connected to the protected component 200; the second end of the first electrostatic protector VD1 is connected to the first end of the first capacitor C1, and the second end of the first capacitor C1 is grounded (it should be noted that the specific form of grounding is not limited in this embodiment, for example, it can be any one of PCB grounding copper foil, PCB ground wire, negative pole of the battery, secondary output terminal grounding of the AC-DC adapter, chassis ground, earth, etc.).

[0104] When this embodiment is in use, most of the high-voltage static electricity breaks through the first static protector VD1 and is stored in the first capacitor C1, becoming low-voltage power energy, thereby reducing the amount of static electricity flowing to the protected component 200, which is beneficial to increasing the service life of the electronic device.

[0105] In this embodiment, the first electrostatic protector VD1 includes one or more of an ESD electrostatic diode (Electro-Staticdischarge, electrostatic protection tube), a TVS diode (Transient Voltage Suppressors, transient suppression diode), a switching diode, a TSS diode (Thyristor Surge Suppressors, surge suppression thyristor), a voltage regulator diode, a varistor, and a gas discharge tube. For example, in an optional embodiment, the first electrostatic protector VD1 can be an ESD electrostatic diode, the first end of the ESD electrostatic diode is connected to the input / output interface 100, and the second end of the ESD electrostatic diode is connected to the first capacitor C1. For example, in another optional embodiment, the first electrostatic protector VD1 can be an ESD electrostatic diode and a varistor, the first end of the ESD electrostatic diode is connected to the input / output interface 100, the second end of the ESD electrostatic diode is connected to the first end of the varistor, and the second end of the varistor is connected to the first capacitor C1. It is clear to those skilled in the art that the specific structure of the first electrostatic protector VD1 in this embodiment can be determined according to actual needs.

[0106] This embodiment also includes a first electronic component connected in series between the input / output interface 100 and the protected component 200 (in this embodiment, the first electronic component is taken as an example of a magnetic bead L1); the first end of the first electronic component is connected to the input / output interface 100, and the second end of the first electronic component is connected to the protected component 200; the first end of the first electrostatic protector VD1 is connected between the input / output interface 100 and the first end of the first electronic component.

[0107] That is to say, the first end of the magnetic bead L1 (i.e., pin 1 of the magnetic bead L1) is connected to the input / output interface 100, and the second end of the magnetic bead L1 (i.e., pin 2 of the magnetic bead L1) is connected to the protected component 200; the first end of the first electrostatic protector VD1 (i.e., pin 1 of the first electrostatic protector VD1) is connected between the input / output interface 100 and the magnetic bead L1, the second end of the first electrostatic protector VD1 (i.e., pin 2 of the first electrostatic protector VD1) is connected to the first end of the first capacitor C1 (i.e., pin 1 of the first capacitor C1), and the second end of the first capacitor C1 (i.e., pin 2 of the first capacitor C1) is connected to the PCB ground copper foil or the PCB ground wire 23.

[0108] In this embodiment, the first electronic component includes a magnetic bead, an inductor, or a resistor. The above embodiment describes an implementation in which the first electronic component is a magnetic bead L1. In other possible implementations, the first electronic component in this embodiment can also be a magnetic bead and a resistor, in which case the first end of the magnetic bead L1 is connected to the input / output interface 100, the second end of the magnetic bead L1 is connected to the first end of the resistor, and the second end of the resistor is connected to the protected component 200. It is clear to those skilled in the art that in other possible implementations, the first electronic component in this embodiment can also be an inductor, a magnetic bead and an inductor, a magnetic bead inductor and a resistor, etc.

[0109] In this embodiment, a magnetic bead L1 is connected to the signal line 300 of the input / output interface 100 of the electronic device and the protected component 200, a first electrostatic protector VD1 is connected between the input / output interface 100 and the magnetic bead L1, and a first capacitor C1 is connected in series between the first electrostatic protector VD1 and the PCB ground copper foil or the PCB ground line 23. When high-voltage static electricity flows from the input / output interface 100, the magnetic bead L1 can prevent most of the high-voltage static electricity from flowing to the protected component 200, so most of the high-voltage static electricity breaks through the first electrostatic protector VD1 and is stored in the first capacitor C1, and becomes low-voltage power energy, thereby reducing the amount of static electricity flowing to the protected component 200, which is beneficial to improving the service life of the electronic device.

[0110] In one possible implementation, please refer to Figure 7-Figure 9 In this embodiment, the first end of the first capacitor C1 is also connected to the first end of the power-consuming element, and the second end of the power-consuming element is connected to the PCB ground copper foil or the PCB ground wire 23.

[0111] In this embodiment, the power-consuming element is provided to facilitate the electric energy stored in the first capacitor C1, thereby reasonably utilizing the energy of static electricity and realizing the conversion of static electricity from "harm to benefit".

[0112] Furthermore, the power-consuming element includes a second resistor R2, which is connected in parallel with the first capacitor C1, the first end of the second resistor R2 (i.e., pin 1 of the second resistor R2) is connected to the second end of the first electrostatic protector VD1, and the second end of the second resistor R2 (i.e., pin 2 of the second resistor R2) is connected to the PCB ground copper foil or the PCB ground wire 23.

[0113] In this embodiment, the resistance of the second resistor R2 is greater than 20 kΩ.

[0114] In this embodiment, the second resistor R2 is provided to consume the electric energy stored in the first capacitor C1 in the form of heat.

[0115] In one possible implementation, please refer to Figure 7-Figure 9 In this embodiment, a second capacitor C2 and a first resistor R1 are connected in series between the second end of the magnetic bead L1 and the protected component 200. The second end of the second capacitor C2 (i.e., pin 2 of the second capacitor C2) is connected to the second end of the magnetic bead L1, the first end of the second capacitor C2 (i.e., pin 1 of the second capacitor C2) is connected to the second end of the first resistor R1 (i.e., pin 2 of the first resistor R1), and the first end of the first resistor R1 (i.e., pin 1 of the first resistor R1) is connected to the protected component 200.

[0116] In this embodiment, a resistor-capacitor circuit is formed by connecting a second capacitor C2 and a first resistor R1 in series between the magnetic bead L1 and the protected component 200. The second capacitor C2 can prevent static electricity from flowing to the protected component 200. The first resistor R1 is equivalent to a voltage divider module, which can divide the residual voltage of static electricity to further reduce the impact of static electricity on the protected component 200.

[0117] Optionally, in this embodiment, in a high-speed circuit or a high-frequency circuit, the resistance of the first resistor R1 is 2.0-2.2Ω; in a medium-low speed circuit or a medium-low frequency circuit, the resistance of the first resistor R1 is 5.1Ω.

[0118] In a possible implementation, a second electrostatic protector VD2 is further provided between the magnetic bead L1 and the second capacitor C2 of this embodiment, the first end of the second electrostatic protector VD2 is connected between the magnetic bead L1 and the second capacitor C2, and the second end of the second electrostatic protector VD2 is connected to the PCB ground copper foil or the PCB ground wire 23.

[0119] In this embodiment, a second electrostatic protector VD2 is provided between the magnetic bead L1 and the second capacitor C2. After the second electrostatic protector VD2 is broken down, the static electricity passing through the magnetic bead L1 can be directed to the ground, thereby further reducing the influence of static electricity on the protected component 200.

[0120] In a possible implementation manner, the electronic device is further provided with a power circuit, the power circuit comprising a power input terminal and a power output terminal;

[0121] The second electrostatic protector VD2 is a triangular tube protector, and the second electrostatic protector VD2 includes a first diode A1 and a second diode A2. The cathode of the first diode A1 is connected to the anode of the second diode A2, and the anode of the first diode A1 is connected to the PCB ground copper foil or the PCB ground wire through the first end of the second electrostatic protector VD2. The cathode of the second diode A2 is connected to the power input end or the power output end through the second end of the second electrostatic protector VD2. The third end of the second electrostatic protector VD2 is arranged between the cathode of the first diode A1 and the anode of the second diode A2, and the third end of the second electrostatic protector VD2 is connected to the second end of the first electronic component.

[0122] Alternatively, the electronic device is further provided with a power circuit, the power circuit comprising a power input terminal and a power output terminal;

[0123] The second electrostatic protector VD2 includes a third diode and a fourth diode, the cathode of the third diode is connected to the anode of the fourth diode, the anode of the third diode is connected to the PCB ground copper foil or the PCB ground wire through the first end of the second electrostatic protector VD2, the cathode of the fourth diode is connected to the power input end or the power output end through the second end of the second electrostatic protector VD2, the third end of the second electrostatic protector VD2 is arranged between the cathode of the third diode and the anode of the fourth diode, and the third end of the second electrostatic protector VD2 is connected to the second end of the first electronic component.

[0124] In one possible implementation, the electronic device has a built-in battery, the battery includes a positive electrode and a negative electrode, and the negative electrode of the battery is connected to a PCB ground copper foil or a PCB ground wire;

[0125] The second electrostatic protector VD2 is a triangular tube protector, and the second electrostatic protector VD2 includes a first diode A1 and a second diode A2. The cathode of the first diode A1 is connected to the anode of the second diode A2, and the anode of the first diode A1 is connected to the PCB ground copper foil or the PCB ground wire through the first end of the second electrostatic protector VD2. The cathode of the second diode A2 is connected to the positive electrode of the battery through the second end of the second electrostatic protector VD2. The third end of the second electrostatic protector VD2 is arranged between the cathode of the first diode A1 and the anode of the second diode A2, and the third end of the second electrostatic protector VD2 is connected to the second end of the first electronic component.

[0126] Alternatively, the electronic device has a built-in battery, the battery includes a positive electrode and a negative electrode, and the negative electrode of the battery is connected to the PCB ground copper foil or the PCB ground wire;

[0127] The second electrostatic protector VD2 includes a third diode and a fourth diode, the cathode of the third diode is connected to the anode of the fourth diode, the anode of the third diode is connected to the PCB ground copper foil or the PCB ground wire through the first end of the second electrostatic protector VD2, the cathode of the fourth diode is connected to the positive electrode of the battery through the second end of the second electrostatic protector VD2, the third end of the second electrostatic protector VD2 is arranged between the cathode of the third diode and the anode of the fourth diode, and the third end of the second electrostatic protector VD2 is connected to the second end of the first electronic component.

[0128] In one possible embodiment, the second electrostatic protector VD2 is a triangular tube protector, and the second electrostatic protector VD2 includes a first diode A1 and a second diode A2, the cathode of the first diode A1 is connected to the anode of the second diode A2, the anode of the first diode A1 is connected to the PCB ground copper foil or the PCB ground wire through the first end of the second electrostatic protector VD2, the cathode of the second diode A2 is connected to the PCB ground copper foil or the PCB ground wire through the second end of the second electrostatic protector VD2, the third end of the second electrostatic protector VD2 is arranged between the cathode of the first diode A1 and the anode of the second diode A2, and the third end of the second electrostatic protector VD2 is connected to the second end of the first electronic component.

[0129] Alternatively, the second electrostatic protector VD2 includes a third diode and a fourth diode, the cathode of the third diode is connected to the anode of the fourth diode, the anode of the third diode is connected to the PCB ground copper foil or the PCB ground wire through the first end of the second electrostatic protector VD2, the cathode of the fourth diode is connected to the PCB ground copper foil or the PCB ground wire through the second end of the second electrostatic protector VD2, the third end of the second electrostatic protector VD2 is arranged between the cathode of the third diode and the anode of the fourth diode, and the third end of the second electrostatic protector VD2 is connected to the second end of the first electronic component.

[0130] Furthermore, the second end of the second electrostatic protector VD2 is also connected to the first end of the third capacitor C3 (i.e., pin 1 of the third capacitor C3), and the second end of the third capacitor C3 (i.e., pin 2 of the third capacitor C3) is connected to the PCB ground copper foil or the PCB ground wire 23.

[0131] Optionally, a power supply voltage (VCC) 410 of the electronic device is connected between the second end of the second electrostatic protector VD2 and the first end of the third capacitor C3.

[0132] In this embodiment, a third capacitor C3 is connected in series between the second end of the second electrostatic protector VD2 and the PCB ground copper foil or the PCB ground line 23. The third capacitor C3 can store electrostatic energy flowing through the second electrostatic protector VD2. Since the power supply voltage 410 of the electronic device is connected to the third capacitor C3, the electrostatic energy stored in the third capacitor C3 can power the electronic device.

[0133] Going a step further, Fig. 9 As shown, the power-consuming element also includes a power supply 400 of the electronic device, a first end of the power supply 400 is connected between the second end of the second electrostatic protector VD2 and the first end of the third capacitor C3, and a second end of the power supply 400 is connected to the PCB ground copper foil or the PCB ground wire 23; a first end of the first capacitor C1 is connected to the first end of the power supply 400 through at least one fifth diode VD6.

[0134] In this embodiment, the first capacitor C1 is connected to the power supply 400 via the fifth diode VD6, so that the energy stored in the first capacitor C1 can be used to supplement the energy of the power supply 400.

[0135] Alternatively, if Figure 8 and Fig. 9 As shown, in this embodiment, a metal sheet 500 is further provided between the second end of the third capacitor C3 and the PCB ground copper foil or the PCB ground line 23 .

[0136] In this embodiment, a metal sheet 500 is arranged between the third capacitor C3 and the ground line to store static electricity, thereby further avoiding abnormal product functions and reducing damage to components in the PCB board.

[0137] The inductor of this embodiment includes a differential mode inductor or a common mode inductor.

[0138] In this embodiment, the signal line 300 between the input / output interface 100 and the protected component 200 can transmit any one of a low-frequency signal, a low-speed signal, a high-speed signal, and a high-frequency signal.

[0139] In this embodiment, the first capacitor C1 includes at least two capacitors whose impedance characteristic curves are located at different resonance points, and the resonance point of each capacitor corresponds to a different interference frequency point of electrostatic discharge or air discharge.

[0140] This embodiment also provides an electronic device, including a shielding shell 210, in which a PCB board and a protected component 200 are arranged, and an input / output interface 100 is also provided on the shielding shell 210. The input / output interface 100 and the protected component 200 are connected through a signal line 300, and the signal line 300 is provided with any of the above electrostatic protection circuits.

[0141] Since the electronic device of this embodiment is provided with the above-mentioned electrostatic protection circuit, when encountering electrostatic discharge, the static electricity has little effect on the components in the electronic device, which is beneficial to prolonging the service life of the electronic device.

[0142] The electrostatic protection circuit of this embodiment is further described in detail below with reference to the accompanying drawings.

[0143] Since the energy of contact discharge is very high (about 2kV to 10kV), and the working voltage of the input and output interface 100 is generally 1.8V-3.3V, that is, the threshold voltage of the input and output interface 100 is 1.8V-3.3V. The electrostatic gun can generate a voltage of 2kV-8kV. If it is directly loaded on the input and output interface 100, the input and output interface 100 cannot withstand it and is directly damaged. Therefore, this embodiment is designed as follows Figure 7 The electrostatic protection circuit shown.

[0144] like Figure 7As shown, one end of a signal line (e.g., a microphone signal line) 300 connected to the external input / output interface 100 is respectively connected to pin 1 of a first electrostatic protector VD1 (e.g., a transient suppression diode, a varistor, a gas discharge tube, etc.) and pin 1 of a magnetic bead L1, pin 2 of the first electrostatic protector VD1 is connected to pin 1 of a first capacitor C1, and pin 2 of the first capacitor C1 is connected to a ground copper foil 23 of a PCB (Printed Circuit Board, hereinafter referred to as "PCB") of the protected component 200, that is, pin 2 of the first electrostatic protector VD1 is connected to a PCB ground copper foil or a PCB ground wire 23 through the first capacitor C1; a second resistor R2 is connected in parallel at both ends of pins 1 and 2 of the first capacitor C1, that is, pin 1 of the second resistor R2 is connected to pin 2 of the first electrostatic protector VD1, and pin 2 of the second resistor R2 is connected to a PCB ground copper foil or a PCB ground wire 23. Pin 2 of the magnetic bead L1 is respectively connected to pin 3 of the second electrostatic protector VD2 (the second electrostatic protector VD2 in this embodiment is a three-pin protection device) and pin 2 of the second capacitor C2. The cathode of the second diode A2 inside the second electrostatic protector VD2 is connected to pin 1 of the third capacitor C3 through pin 2 of the second electrostatic protector VD2 (if the third capacitor C3 is a polarized capacitor, pin 1 must be positive, and there is no restriction if it is non-polar). At the same time, pin 1 of the third capacitor C3 and pin 2 of the second electrostatic protector VD2 are connected to the power supply voltage (VCC) in the PCB board; pin 2 of the third capacitor C3 is connected to the PCB ground copper foil or PCB ground wire 23. The anode of the first diode A1 in the second electrostatic protector VD2 is connected to the PCB ground copper foil or PCB ground wire 23 through pin 1 of the second electrostatic protector VD2. Pin 1 of the second capacitor C2 is connected to pin 2 of the resistor R1, and pin 1 of the resistor R1 is connected to the pin 200 of the protected component (e.g., the signal pin of the chip). The PCB ground copper foil or PCB ground wire 23 can be a ground wire or a ground plane, preferably a plane. A metal shielding cover 210 is added above the protected component 200 (such as a chip) and its peripheral components. The metal shielding cover 210 is welded on the PCB board and completely covers the protected component 200 and its peripheral components.

[0145] In this embodiment, the first electrostatic protector VD1, the first energy storage capacitor C1, and the second resistor R2 form a pre-stage discharge channel. The breakdown voltage of the second electrostatic protector VD2 is slightly higher than the highest level of the signal line 303. Because the second resistor R2 is connected across the first capacitor C1, even if the first capacitor C1 has a charge, it will be consumed by the second resistor R2 in the form of heat. When there is no static discharge to the input / output interface 100, it can be considered that the level across the first capacitor C1 is 0. In this way, when the signal line 300 is working normally, the second electrostatic protector VD2 does not reach the critical state of breakdown, and is completely cut off, which does not affect the normal operation of the signal line 303. If the breakdown voltage of the second electrostatic protector VD2 is lower than the highest level of the signal, in the normal transmission process of the signal, when the level of the signal is at the breakdown threshold voltage of the second electrostatic protector VD2, the signal will be clamped, that is, the signal will be "topped" when it exceeds the breakdown threshold voltage of the second electrostatic protector VD2, resulting in distortion of the signal waveform, which does not meet the hardware design requirements. Therefore, the breakdown threshold voltage of the second electrostatic protector VD2 should be slightly higher than the highest level of the signal, so that the signal will not exceed the threshold voltage of the second electrostatic protector VD2 during normal transmission, that is, the second electrostatic protector VD2 does not work during normal signal transmission.

[0146] When the signal line 303 transmits a high-speed signal or a high-frequency signal, since the swing amplitude of the high-speed signal or the high-frequency signal is relatively low and will not be higher than the power supply voltage (for example, the commonly used power supply voltage is 3.3V, 1.8V, etc.), as long as the threshold voltage sense of the breakdown of the first electrostatic protector VD1 is slightly higher than the swing amplitude of the high-speed signal or the high-frequency signal, the first electrostatic protector VD1 will not be broken down. Therefore, even if the first capacitor C1 is connected to the PCB ground copper foil or the PCB ground wire 23, the first capacitor C1 will not short-circuit the high-speed signal or the high-frequency signal in the signal line 303 to the PCB ground copper foil or the PCB ground wire 23 to the ground (the high-speed signal or the high-frequency signal is similar to the AC signal, and the AC signal passes through the capacitor, which is equivalent to a short circuit). Therefore, it does not affect the normal transmission of the high-speed signal or the high-frequency signal on the signal line 303, and complies with the design rules of the high-speed signal or the high-frequency signal.

[0147] When 4kV to 12kV contact discharge is injected into the external input / output interface 100 of the signal line 303, the first electrostatic protector VD1 is instantly broken down, and a huge discharge current is released to the negative electrode through the positive electrode of the first capacitor C1 (the capacitor is equivalent to a short circuit at this time), and finally to the PCB ground copper foil or PCB ground wire 23, and the electrostatic charge is instantly gathered between the two plates of the first capacitor C1, that is, the two plates of the first capacitor C1 form an electrostatic field, and the electrostatic charge of 4kV to 12kV contact discharge is stored between the two plates of the first capacitor C1, and then gradually consumed in a heating manner through the second resistor R2. When the electrostatic charge of the contact discharge encounters the magnetic bead L1, the magnetic bead L1 will present a very high impedance, preventing the electrostatic current from passing through the magnetic bead L1 quickly, and at the same time generating a high voltage drop at both ends of the magnetic bead L1, blocking the electrostatic charge as much as possible in the front-stage discharge channel composed of the first electrostatic protector VD1, the first capacitor C1, and the second resistor R2 for full discharge. Since the capacitance of the first capacitor C1 is relatively large, 75% to 85% of the electrostatic charge of contact discharge can be absorbed and stored at both ends of the first capacitor C1. The second resistor R2 is connected across the first capacitor C1, and the second resistor R2 will gradually consume the electrostatic charge stored in the first capacitor C1 in a heating manner. The second resistor R2 is selected to have a relatively large resistance (preferably above 20kΩ), because when the input / output interface 100 injects contact discharge and the first electrostatic protector VD1 breaks down, if the second resistor R2 has a low value (for example, tens of ohms), the second resistor R2 will discharge the electrostatic charge to the PCB ground copper foil or PCB ground wire 23 in a way of connecting to the PCB ground copper foil or PCB ground wire. The original intention of the design is to store the electrostatic charge of contact discharge in the first capacitor C1, which is the core idea of ​​the design, especially for battery-powered devices or products. When a battery-powered device or product is performing air discharge or contact discharge, there is no channel for discharge, and it cannot be like a device or product with an AC-DC adapter, which can discharge the high-voltage electrostatic charge to the ground through the device or product through the AC-DC adapter.

[0148] The second electrostatic protector VD2 and the third capacitor C3, which are connected across the three networks of the signal line 300, the power supply voltage 410, the PCB ground copper foil or the PCB ground line 23, form a second-level discharge channel. The positive electrode of the internal diode in the second electrostatic protector VD2, which is connected across the two networks of the signal line 300 and the power supply voltage 410, is connected to the signal line 300, and the negative electrode is connected to the third capacitor C3 at the end of the power supply voltage 410. The highest level of the signal is slightly lower than the power supply voltage 410, so that when the signal line 300 is working normally, the diode in the second electrostatic protector VD2 is in a cut-off state, which does not affect the normal operation of the signal line 300. When the +4kV~+12kV contact discharge electrostatic charge is blocked by the discharge circuit composed of the first electrostatic protector VD1, the first energy storage capacitor C1, the second resistor R2, etc. and the magnetic bead L1, about 15%~25% of the energy enters the first diode A1 and the third capacitor C3 in the second electrostatic protector VD2 connected to the rear stage of the magnetic bead L1, and the electrostatic residual pressure at this time is higher than the power supply voltage 410 plus the voltage drop of the second electrostatic protector VD2. The electrostatic residual pressure will quickly inject electrostatic charge into the positive and negative electrodes of the third energy storage capacitor C3 of the power supply voltage 410 through the first diode A1 in the second electrostatic protector VD2. The electrostatic residual pressure is stored between the two plates of the third capacitor C3. The electrostatic residual pressure is converted into the energy of the power supply voltage 410 in the third capacitor C3, which is equivalent to charging the power supply voltage 410 and supplying power to the load of the entire power supply network. The third capacitor C3 is an electrostatic energy converter, which converts high-voltage static electricity into power energy that can supply power to the PCB board load, realizing the conversion of "turning harm into benefit". The secondary discharge circuit composed of the second electrostatic protector VD2 and the third capacitor C3 can clamp the signal between the power supply voltage 410 plus the forward voltage drop of the second electrostatic protector VD2 and the forward voltage drop of the second electrostatic protector VD2, greatly weakening the interference of high-voltage electrostatic energy to the sensitive pins (such as signal line pins) of the protected component 200 and the inside of the protected component 200. In this embodiment, the forward voltage drop of the second electrostatic protector VD2 is about 0.2V to 0.7V.

[0149] If the voltage drop of the second electrostatic protector VD2 is 0.7V (such as a silicon tube), the clamping voltage of the signal line 300 is between -0.7V and VCC+0.7V. When the input / output interface 100 is injected with a contact discharge of 2kV to 8kV positive voltage, the clamping voltage of the signal line 300 is between 0V and VCC+0.7V, and the subsequent circuits such as the protection C2, R1, and the protected component 200 will not be damaged, and it is not easy to cause functional abnormalities. When the input / output interface 100 is injected with a contact discharge of 2kV to 8kV negative voltage, the clamping voltage of the signal line 300 is between -0.7V and 0V, and the subsequent circuits such as the protection C2, R1, and the protected component 200 will not be damaged, and it is not easy to cause functional abnormalities.

[0150] If the voltage drop of the second electrostatic protector VD2 is 0.3V (e.g., a germanium tube), the clamping voltage of the signal line 300 is between -0.3V and VCC+0.3V. When the input / output interface 100 is injected with a contact discharge of 2kV to 8kV positive voltage, the clamping voltage of the signal line 300 is between 0V and VCC+0.3V, and the subsequent circuits such as the protection C2, R1, and the protected component 200 will not be damaged, and it is not easy to cause functional abnormalities. When the input / output interface 100 is injected with a contact discharge of 2kV to 8kV negative voltage, the clamping voltage of the signal line 300 is between -0.3V and 0V, and the subsequent circuits such as the protection C2, R1, and the protected component 200 will not be damaged, and it is not easy to cause functional abnormalities.

[0151] Whether the second electrostatic protector VD2 is selected as a silicon tube or a germanium tube is determined according to the actual application situation. The principle is that the voltage drop of the diode VD4 and the diode VD5 should slightly exceed the working level of the signal line 300. If the voltage drop of the diode VD4 and the diode VD5 is less than the working level threshold of the signal line 300, the signal of the signal line 300 will be "clipped". If the voltage drop of the diode VD4 and the diode VD5 is much larger than the working level threshold of the signal line 300, a higher electrostatic residual voltage will be injected into the subsequent circuits such as C2, R1, and the protected component 200, resulting in abnormal function or damage of the subsequent circuits.

[0152] In addition, the second electrostatic protector VD2 is specifically selected from silicon tubes, germanium tubes, or other types of diodes, but a diode with a higher switching speed is required, so that the response speed of the second electrostatic protector can catch up with the response speed of 0.6ns electrostatic discharge.

[0153] In this embodiment, the second capacitor C2 and the first resistor R1 connected in series between the second electrostatic protector VD2 and the chip form a third-level protection circuit. The resistor-capacitor circuit composed of the second capacitor C2 and the first resistor R1 actually forms a bandpass filter. After being discharged by the secondary discharge circuit composed of the second electrostatic protector VD2 and the third capacitor C3, about 5% of the energy is still injected into the protected component 200, but the second capacitor C2 has the characteristics of blocking high frequency through low frequency and blocking direct current through AC, which can directly prevent low-frequency electrostatic energy from being injected into the protected component 200. The second capacitor C2 can be selected according to the operating frequency of the signal. If the operating frequency of the signal is high, the second capacitor C2 can select a capacitor with a higher operating frequency; in this way, the cutoff frequency of the second capacitor C2 does not affect the normal operation of the signal, but can prevent the electrostatic residual pressure below the cutoff frequency (higher frequency) of the second capacitor C2 from being injected into the chip sensitive pins and the inside of the chip. If the operating frequency of the signal is low, the second capacitor C2 can select a capacitor with a lower operating frequency; it can prevent the electrostatic residual pressure below the cutoff frequency (lower frequency) of the second capacitor C2 from being injected into the chip sensitive pins and the inside of the chip. The smaller the capacitance of the second capacitor C2, the longer the frequency band for blocking the electrostatic residual voltage, that is, the smaller the capacitance of the second capacitor C2, the more it can block the electrostatic residual voltage in the medium and low frequency bands. It blocks about 1% to 2% of the electrostatic residual voltage. The first resistor R1 is connected in series between the second capacitor C2 and the chip. The first resistor R1 is equivalent to a voltage divider module. After the second capacitor C2 isolates the medium and low frequency electrostatic residual voltage, adding the first series voltage divider resistor R1 to the second capacitor C2 can divide the residual voltage of the lightning strike, further reducing the sensitive pins of the protected component 200 and the internal disturbance of the protected component 200. In high-speed circuits or high-frequency circuits, the first resistor R1 generally selects a 2.0 ohm or 2.2 ohm resistor; in medium and low speed circuits or medium and low frequency circuits, the first resistor R1 generally selects a 5.1 ohm resistor. After the voltage is divided by the first resistor R1, the residual voltage of the lightning strike can be limited to 2% to 3%. The first resistor R1 can be a resistor with a package size of 0201 or above (preferably 0402). It is not recommended to select a package size below 0201. The power of the first resistor R1 should meet the discharge requirements to avoid a package size that is too small and insufficient power.

[0154] It should be noted that the discharge channels of each level in this embodiment cannot be interchanged. For example, if the second resistor R2 is placed at the input and output interface 100, the high voltage generated by the electrostatic gun will generate a 2A to 30A discharge current (different specifications are different, and the discharge current is different at different time points) after passing through the second resistor R2, so a very high voltage drop will be generated at the second resistor R2.

[0155] If the resistance is too small, it will not be able to prevent static electricity and will generate huge power consumption. For example, if the second resistor R2 is 2 ohms, according to the power calculation formula p = I 2R = 30 × 30 × 2 = 1800W, and the density of PCB boards in current products is getting higher and higher. The resistors of electronic components in PCB boards will be selected from 0201, 0402, 0805, 1206 packages and other patches. As long as the contact discharge injects static electricity, the second resistor R2 cannot withstand it and burns immediately. Table 2 shows the power withstand of resistors of various package types: the power withstand of the resistor of 0201 package is 1 / 20W, the power withstand of the resistor of 0402 package is 1 / 16W, the power withstand of the resistor of 0603 package is 1 / 10W, the power withstand of the resistor of 0805 package is 1 / 8W, and the power withstand of the resistor of 1206 package is 1 / 4W. According to the above calculation, when the second resistor R2 is selected as 2 ohms, the power consumption reaches 1800W. The resistors of 0201 package, 0402 package, 0603 package, 0805 package, and 1206 package cannot meet this requirement and will be burned out instantly.

[0156] Table 2 Power handling of resistors of various package types

[0157] PCB package type Power handling capacity 0201 1 / 20W 0402 1 / 16W 0603 1 / 10W 0805 1 / 8W 1206 1 / 4W

[0158] The second resistor R2 has a large resistance value, which will affect the function of the product. Assuming that the input and output interface 100 is an audio headphone output, the second resistor R2 has a large resistance value, and the output power will be consumed in the second resistor R2, resulting in very small power transmitted to the external headphone, which does not meet the design requirements. For example, if the second resistor R2 is designed to be 10Ω, the headphone output current is 500mA, and the voltage drop at the second resistor R2 is 500mA×10Ω=5W, which obviously does not meet the design requirements. In addition, if the input and output interface 100 is a USB interface, the resistance exceeds 10Ω, which will cause the USB eye diagram to be unable to open, which does not meet the design requirements.

[0159] In the present application, the first electrostatic protector VD1 is connected in series with the first capacitor C1 and is directly connected to the input and output interface 100. When the high-voltage static electricity generated by the electrostatic gun passes through, it will exceed the threshold value of the first electrostatic protector VD1 and will be turned on immediately. For the instantaneous pulse voltage, the first capacitor C1 is equivalent to a short circuit, that is, an electromotive force will be generated on the two plates of the first capacitor C1, that is, the energy of the high-voltage static electricity is stored on the two plates of the first capacitor C1. The larger the capacitance of the first capacitor C1, the more static electricity energy can be stored, and the better the static electricity absorption ability.

[0160] According to the calculation, we know that:

[0161] When the electrostatic contact discharge voltage is 2kV, the charge stored in the electrostatic gun is Q. According to Coulomb's law, the charge stored in the electrostatic gun is Q1=U1×C=2kV×150pF=3x10 -7 C.

[0162] When the electrostatic contact discharge voltage is 4kV, the charge stored in the electrostatic gun is Q. According to Coulomb's law, the charge stored in the electrostatic gun is Q2=U2×C=4kV×150pF=6x10 -7 C.

[0163] When the electrostatic contact discharge voltage is 6kV, the charge stored in the electrostatic gun is Q. According to Coulomb's law, the charge stored in the electrostatic gun is Q3=U3×C=6kV×150pF=9x10 -7 C.

[0164] When the electrostatic contact discharge voltage is 8kV, the charge stored in the electrostatic gun is Q. According to Coulomb's law, the charge stored in the electrostatic gun is Q4=U4×C=8kV×150pF=12x10 -7 C.

[0165] When the electrostatic contact discharge voltage is 12kV, the charge stored in the electrostatic gun is Q. According to Coulomb's law, the charge stored in the electrostatic gun is Q5=U5×C=12kV×150pF=18x10 -7 C.

[0166] In this embodiment, the positions of the magnetic bead L1 and the second capacitor C2 cannot be interchanged. The magnetic bead is placed between the second electrostatic protector VD2 and the series combination of the first electrostatic protector VD1 and the first capacitor C1. When the high-voltage static electricity generated by the electrostatic gun passes through, 80% of the static electricity energy will be stored in the first capacitor C1 by the series combination of the first electrostatic protector VD1 and the first capacitor C1; but there is still 20% of the energy flowing through, which is also very high energy for the input and output interface 100, far exceeding the threshold value of the input and output interface 100. The characteristic of the magnetic bead L1 is that it exhibits a very high impedance for the fast (ns level) pulse of static electricity, preventing static electricity from passing through, that is, when static electricity comes to the magnetic bead L1, it will be reflected back by the magnetic bead L1, allowing the first electrostatic protector VD1 and the first capacitor C1 series combination to fully absorb and store at both ends of the first capacitor C1. Only about 5% of the static electricity passes through the magnetic bead L1, and about 1% of the energy will be consumed by the magnetic bead L1 in the form of heat loss. Fig.10 : is a characteristic curve diagram of the impedance and frequency of the magnetic beads in one embodiment of the present application; Fig.10 As shown, the resonance point of the magnetic bead L1 of this embodiment is about 1 GHz, and the impedance of the magnetic bead at the resonance point is the highest, about 380Ω; Fig.10 It can be seen that on the left side of the resonance point of the magnetic bead L1 (within the bandwidth range of 1Hz to 1GHz), the magnetic bead L1 exhibits the characteristics of inductance; on the right side of the resonance point of the magnetic bead (within the bandwidth range of more than 1GHz), the magnetic bead L1 exhibits the characteristics of capacitance; combined with Figure 3From Table 1, we can see that the minimum discharge period of contact discharge is 0.6ns. The conversion formula between period T and frequency f is as follows:

[0167] T = 1 / f,

[0168] Then f = 1 / T = 1 / 0.6x10 -9 s = 1.667x10 9 Hz=1.667GHz, which means the highest frequency band of static electricity interference is about 1.667GHz.

[0169] Combination Fig.10 It can be seen that the impedance of the magnetic beads in this embodiment reaches a maximum at the resonance point of 1 GHz, which is about 383 ohms, reaches 100 ohms at 60 MHz, 200 ohms at 160 MHz, 300 ohms at 290 MHz, 300 ohms at 2 GHz, and 220 ohms at 3 GHz. That is, the magnetic beads in this embodiment show higher impedance in the static interference frequency band.

[0170] and Figure 5 The first level in the circuit stores most of the energy (about 90% of the energy) generated by the static electricity in the two plates of the capacitor C2, greatly weakening the impact of the static electricity on the device pins and signal routing caused by the pulse current passing through the copper foil 23 of the whole board, especially the common ground impedance causing the communication between the two devices to produce garbled codes (such as packet loss, crash, etc.), which may damage the device in serious cases. At the same time, the contact discharge injected into the external interface will not affect the normal function of the internal pins of the protected component 200.

[0171] Fig.11 for Fig.40 Corresponding PCB board layout and wiring diagram; please continue to refer to Fig.11 and Fig.40, the input / output interface 100 is exposed outside the shielding shell or near the opening of the shielding shell, and the input / output interface 100 is, for example, a USB interface. Pin 1 of the first electrostatic protector VD1 is connected to the input / output interface 100, and pin 2 of the first electrostatic protector VD1 is connected to pin 1 of the first capacitor C1 and pin 1 of the second resistor R2 through the signal line 230, and pin 2 of the first capacitor C1 and pin 2 of the second resistor R2 are connected to the PCB ground copper foil 23. Pin 1 of the magnetic bead L1 is connected to pin 1 of the first electrostatic protector VD1 through the signal line 303, and pin 2 of the magnetic bead L1 is connected to pin 1 of the second electrostatic protector VD2 (bidirectional electrostatic protector) and pin 2 of the second capacitor C2 through the signal line 303, and pin 2 of the second electrostatic protector VD2 is connected to the PCB ground copper foil 23. Pin 1 of the second capacitor C2 is connected to pin 2 of the first resistor R1 through the signal line 97, and pin 1 of the first resistor R1 is connected to the chip 200 (protected component) through the signal line 98. When 4kV to 8kV contact discharge is injected into the input / output interface 100, an instantaneous high voltage is generated on the first signal line 330 between the input / output interface 100 and the first electrostatic protector VD1, breaking down the first electrostatic protector VD1, and generating an electrostatic discharge current i2 of more than ten amperes in the first electrostatic protector VD1. The electrostatic discharge current i2 is injected into pin 1 (positive pin) of the first capacitor C1. Due to the "DC isolation and AC pass" characteristic of the capacitor, a large amount of electrostatic charge is instantly injected into the positive plate inside the first capacitor C1 (the positive and negative electrodes contain large-area plates, Fig.11 Not marked), the negative electrode plate inside the first capacitor C1 (the positive and negative electrodes contain large-area plates, Fig.11 The electrostatic charge induced on the negative plate inside the first capacitor C1 is connected to the negative pin 22 of the first capacitor C1, and finally the induced electrostatic charge is injected into the PCB ground copper foil or PCB ground wire 23. A large amount of electrostatic charge is instantly stored in the form of low electromotive force on the two positive and negative plates of the first capacitor C1 ( Fig.11 Not marked), and then gradually releases energy to the second resistor R2 connected in parallel at both ends of the first capacitor C1, generating a current i3, slowly consuming the electrostatic charge stored in the two positive and negative plates of the first capacitor C1 until all of it is consumed.

[0172] The electrostatic energy absorbed by the first electrostatic protector VD1 is about 85% to 90% of the energy injected into the input / output interface 100. After passing through the first electrostatic protector VD1, there is still a certain residual pressure on the second signal line 303. The instantaneous electrostatic discharge i4 encounters the 1st pin of the magnetic bead L1. Due to the instantaneous electrostatic interference frequency band of 16.67MHz to 1.667GHz, a very high impedance is reflected in the magnetic bead L1 ( Fig.10The impedance frequency characteristic curve of the magnetic bead L1 is given to prevent the electrostatic current from passing through the magnetic bead L1 quickly, and at the same time generate a higher voltage drop at both ends of the magnetic bead L1, so as to block the electrostatic charge as much as possible in the front-stage discharge channel composed of the first electrostatic protector VD1, the first capacitor C1, and the second resistor R2 for full discharge. Only a very small residual current i5 passes through the magnetic bead L1. When the electrostatic residual voltage passing through the magnetic bead L1 exceeds the threshold value of the second electrostatic protector VD2 connected across the signal line 303, the second electrostatic protector VD2 is instantly turned on to generate a discharge current i6 to the PCB ground copper foil 23 or the ground line 23. At this time, the residual voltage injected into the second capacitor C2 is very small. After the "DC isolation and AC passing" of the capacitor C2, the low-frequency component passing through the second capacitor C2 is basically filtered out by the second capacitor C2. After the voltage is divided by the first resistor R1, the electrostatic residual voltage that finally reaches the pin 16 of the chip 200 (the protected component) is almost negligible, that is, there is no interference with the pin 16 signal of the protected component 200, and it does not affect the normal operation of the product, and it will not damage the chip 200 (the protected component).

[0173] The following analysis is based on the electrostatic contact discharge voltage of 4kV:

[0174] When the electrostatic contact discharge voltage is 4kV, the charge stored in the electrostatic gun is Q. According to Coulomb's law, the charge stored in the electrostatic gun is Q = U2 × C = 4kV × 150pF = 6x10 -7 C. A large amount of static electricity passes through the positive and negative plates of the first capacitor C1 instantly. When the positive and negative plates of the first capacitor C1 reach the highest electromotive force, the amount of charge stored in the positive and negative plates of the first capacitor C1 is Q, which absorbs almost 85% to 90% of the static charge energy. The first capacitor C1 absorbs 85% of the charge in the static gun, which is 5.1x10 -7 C; the first capacitor C1 absorbs 90% of the charge in the electrostatic gun, which is 5.4x10 -7 C.

[0175] According to the capacitor withstand voltage of compact products, 6.3V is generally selected, and the safe working voltage cannot exceed 5V (80% derating of the capacitor withstand voltage), so the voltage U1 of the static charge stored at both ends of the first capacitor C1 is 5V. According to Coulomb's law, when the electrostatic contact discharge voltage is 2kV, the first capacitor C1 absorbs 90% of the charge in the electrostatic gun, and the required capacitance of the first capacitor C1 is 0.54μF. That is, when the electrostatic contact discharge voltage is 2kV, the first capacitor C1 is selected with a capacitance of 0.54μF, and the first capacitor C1 absorbs 90% of the charge in the electrostatic gun, which is 2.7x10 -7The charge amount of C, the voltage of the static charge at both ends of the first capacitor C1 is about 5V, and the 5V voltage will not cause the danger of high-voltage breakdown to the power supply network connected to the positive electrode of the first capacitor C1. According to the Chinese G6.2B / T1762 standard (equivalent to the international standard IEC61000-4-2), the input / output interface 100 needs to be contacted with positive discharge 10 times and then negatively discharged 10 times. That is, during the 10 times of positive discharge, the first capacitor C1 needs to absorb 10 times 0.54μF to avoid contacting with positive discharge 10 times and injecting it into the input / output interface 100. Therefore, the first capacitor C1 is selected as 0.54μF×10=5.4μF. Considering that there is a positive and negative tolerance in the capacitance of the first capacitor C1, a margin should be reserved. In actual use, the first capacitor C1 can be selected as 6.8μF.

[0176] When the electrostatic contact discharge voltage is 4kV, and the first capacitor C1 absorbs 90% of the charge in the electrostatic gun, the required capacitance of the first capacitor C1 is 1.08μF. That is, when the electrostatic contact discharge voltage is 4kV, and the first capacitor C1 is selected to have a capacitance of 1.08μF, the first capacitor C1 absorbs 90% of the charge in the electrostatic gun, which is 5.4x10 -7 The charge amount of C, the voltage of the static charge at both ends of the first capacitor C1 is about 5V, and the 5V voltage will not cause the danger of high-voltage breakdown to the power supply network connected to the positive electrode of the first capacitor C1. According to the Chinese G6.2B / T1762 standard (equivalent to the international standard IEC61000-4-2), the input / output interface 100 needs to be contacted with positive discharge 10 times and then negatively discharged 10 times. That is, during the 10 times of positive discharge, the first capacitor C1 must absorb 10 times 1.08μF to avoid contacting the positive discharge 10 times and injecting it into the input / output interface 100. Therefore, the first capacitor C1 is selected as 1.08μF×10=10.8μF. In actual use, the first capacitor C1 can be selected as 22μF, or the first capacitor C1 can select two capacitors: 10μF capacitor + 2.2μF capacitor (considering that the capacitance values ​​of the two capacitors of the first capacitor C1 have positive and negative tolerances, a margin must be reserved).

[0177] When the electrostatic contact discharge voltage is 6kV, the first capacitor C1 absorbs 90% of the charge in the electrostatic gun, and the required capacitance of the first capacitor C1 is 1.62μF; that is, when the electrostatic contact discharge voltage is 6kV, the first capacitor C1 is selected to have a capacitance of 1.62μF, and the first capacitor C1 absorbs 90% of the charge in the electrostatic gun, which is 8.1x10 -7The charge amount of C, the voltage of the static charge at both ends of the first capacitor C1 is about 5V, and the 5V voltage will not cause the danger of high-voltage breakdown to the power supply network connected to the positive electrode of the first capacitor C1. According to the Chinese G6.2B / T1762 standard (equivalent to the international standard IEC61000-4-2), the input / output interface 100 needs to be positively discharged 10 times and then negatively discharged 10 times. That is, during the 10 times of positive discharge, the first capacitor C1 needs to absorb 10 times 1.62μF to avoid the contact positive discharge 10 times injected into the input / output interface 100. Therefore, the first capacitor C1 is selected as 1.62μF×10=16.2μF. In actual use, the first capacitor C1 can be selected as 22μF, or the first capacitor C1 can select two capacitors: 10μF capacitor + 6.8μF capacitor (considering that the capacitance values ​​of the two capacitors of the first capacitor C1 have positive and negative tolerances, a margin must be reserved).

[0178] When the electrostatic contact discharge voltage is 8kV, the first capacitor C1 absorbs 90% of the charge in the electrostatic gun, and the required capacitance of the first capacitor C1 is 2.16μF; that is, when the electrostatic contact discharge voltage is 8kV, the first capacitor C1 is selected to have a capacitance of 2.16μF, and the first capacitor C1 absorbs 90% of the charge in the electrostatic gun, which is 10.8x10 -7 The charge amount of C, the voltage of the static charge at both ends of the first capacitor C1 is about 5V, and the 5V voltage will not cause the danger of high-voltage breakdown to the power supply network connected to the positive electrode of the first capacitor C1. According to the Chinese G6.2B / T1762 standard (equivalent to the international standard IEC61000-4-2), the input / output interface 100 needs to be contacted with positive discharge 10 times and then negatively discharged 10 times. That is, during the 10 times of positive discharge, the first capacitor C1 must absorb 10 times 2.16μF to avoid contacting the positive discharge 10 times and injecting it into the input / output interface 100. Therefore, the first capacitor C1 is selected as 2.16μF×10=21.6μF. In actual use, the first capacitor C1 can be selected as 22μF (considering that there is a positive and negative tolerance in the capacitance of the two capacitors of the first capacitor C1, a margin must be reserved).

[0179] When the electrostatic contact discharge voltage is 10kV, the first capacitor C1 absorbs 90% of the charge in the electrostatic gun, and the required capacitance of the first capacitor C1 is 3.24μF; that is, when the electrostatic contact discharge voltage is 10kV, the first capacitor C1 is selected to have a capacitance of 3.24μF, and the first capacitor C1 absorbs 90% of the charge in the electrostatic gun. -7The charge amount of C, the voltage of the static charge at both ends of the first capacitor C1 is about 5V, and the 5V voltage will not cause the danger of high-voltage breakdown to the power supply network connected to the positive electrode of the first capacitor C1. According to the Chinese G6.2B / T1762 standard (equivalent to the international standard IEC61000-4-2), the input / output interface 100 needs to be positively discharged 10 times and then negatively discharged 10 times. That is, during the 10 times of positive discharge, the first capacitor C1 must absorb 10 times 3.24μF to avoid the contact positive discharge 10 times injected into the input / output interface 100. Therefore, the first capacitor C1 is selected as 3.24μF×10=32.4μF. In actual use, the first capacitor C1 can be selected as 32.4μF (considering that there is a positive and negative tolerance in the capacitance of the two capacitors of the first capacitor C1, a margin must be reserved).

[0180] It should be noted that the advantage of this solution is that after the input / output interface 100 is subjected to contact positive discharge 10 times: when the electrostatic contact discharge voltage is 4 kV, 5.4x10 -7 C×10=5.4x10 -6 When the input / output interface 100 contacts the negative discharge 10 times, the charge stored on the two plates of the first capacitor C1 is 5.4x10 -7 When the charge of C contacts negative discharge 10 times, the negative charge released by the electrostatic gun is neutralized. That is, the contact discharge voltage of the electrostatic gun is -4kV, and 5.4x10 -6 The negative charge of C will contact the electrostatic gun and the discharge voltage is 4kV. 10 times will generate 5.4x10 -6 The positive charge of C is neutralized and has no destructive effect on the entire circuit.

[0181] When the electrostatic contact discharge voltage is 6 kV, 8.1x10 -7 C×10=8.1x10 -6 When the input / output interface 100 contacts the negative discharge 10 times, the charge stored on the two plates of the first capacitor C1 is 8.1x10 -6 When the charge of C contacts negative discharge 10 times, the negative charge released by the electrostatic gun is neutralized. That is, the contact discharge voltage of the electrostatic gun is -6kV, and 8.1x10 -7 C×10=8.1x10 -6 The negative charge of C will contact the electrostatic gun and the discharge voltage will be 6kV. 10 times will generate 8.1x10 -7 C×10=8.1x10 -6 The positive charge of C is neutralized and has no destructive effect on the entire circuit.

[0182] When the electrostatic contact discharge voltage is 8 kV, 10.8 x 10 -7 C×10=10.8x10 -6 When the input / output interface 100 contacts the negative discharge 10 times, the charge stored on the two plates of the first capacitor C1 is 10.8x10 -6 When the charge of C contacts negative discharge 10 times, the negative charge released by the electrostatic gun is neutralized. That is, the contact discharge voltage of the electrostatic gun is -8kV, and 10.8x10 -7 C×10=10.8x10 -6 The negative charge of C will contact the electrostatic gun and the discharge voltage will be 8kV. 10 times will generate 10.8x10 -7 C×10=10.8x10 -6 The positive charge of C is neutralized and has no destructive effect on the entire circuit.

[0183] When the electrostatic contact discharge voltage is 10 kV, 16.2 x 10 -7 C×10=16.2x10 -6 When the input / output interface 100 contacts the negative discharge 10 times, the charge stored on the two plates of the first capacitor C1 is 16.2x10 -6 When the charge of C contacts negative discharge 10 times, the negative charge released by the electrostatic gun is neutralized. That is, the contact discharge voltage of the electrostatic gun is -8kV, and 16.2x10 -7 C×10=16.2x10 -6 The negative charge of C will contact the electrostatic gun and the discharge voltage will be 8kV. 10 times will generate 16.2x10 -7 C×10=16.2x10 -6 The positive charge of C is neutralized and has no destructive effect on the entire circuit.

[0184] One end of the second electrostatic protector VD2 is connected to the magnetic bead L1, and the other end is connected to the second capacitor C2. After being absorbed by the first electrostatic protector VD1, the current still has 10% to 15% residual pressure injected into the magnetic bead L1, generating a transient current i4, but the magnetic bead L1 has a large AC impedance for the transient current i4, similar to the inductance characteristic of "always hindering the sudden change of current", part of which will be consumed in the form of heat loss, and the other part will be prevented from passing through the magnetic bead L1, returning to the first electrostatic protector VD1, fully absorbed, and discharged to the first capacitor C1 for storage.

[0185] A very small part of the instantaneous current i7 passes through the magnetic bead L1. If the residual voltage of the static electricity exceeds the breakdown voltage of the second static electricity protector VD2, the second static electricity protector VD2 will break down and finally discharge to the PCB ground copper foil or PCB ground wire 23. At this time, the static electricity current i7 injected into the PCB ground copper foil or PCB ground wire 23 is small, and the residual voltage generated is small, which has a very weak impact on the sensitive signal routing in the entire PCB board.

[0186] The other end of the second electrostatic protector VD2 is connected to the second capacitor C2. The static electricity absorbed by the second electrostatic protector VD2 generates a relatively low residual voltage, which is very weak after being isolated by the second capacitor C2. The impact on the protected component 200 and the external input / output interface 100 is very weak.

[0187] The capacitance of the second capacitor C2 is very important. The smaller the capacitance, the more it can isolate the static electricity components in the high, medium and low frequency bands. The larger the capacitance, the more it can isolate the static electricity components in the medium and low frequency bands. The smaller the capacitance, the more static electricity components can be isolated. However, at the same time, there is also a certain range of isolation for the transmitted signal, which may affect the signal quality. Therefore, it should be determined according to the actual signal frequency.

[0188] A first resistor R1 is connected in series between the second capacitor C2 and the protected component 200. The first resistor R1 is equivalent to a voltage divider module. After the second capacitor C2 isolates the low-frequency electrostatic residual pressure, adding the first voltage divider resistor R1 in series to the second capacitor C2 can divide the residual pressure of the electrostatic, further reducing the impact on the protected component 200. After the voltage is divided by the series voltage divider resistor, the residual pressure of the electrostatic can be limited to 2% to 3%.

[0189] Fig.12 This is a schematic diagram of an electrostatic protection circuit provided by another embodiment of the present application. Fig.12 ,and Figure 7 The difference from the electrostatic protection circuit shown is that in this embodiment, a plurality of first capacitors C1 connected in parallel are arranged between the second end of the first electrostatic protector and the PCB ground copper foil or the PCB ground wire 23 (only four first capacitors C1 are shown in the figure).

[0190] Specifically, the first capacitor C1 in this embodiment includes C4, C5, C6, and C7, and C4, C5, C6, C7, and R2 are connected in parallel and then connected in series with the first electrostatic protector VD1. Figure 7 The circuits shown are identical.

[0191] In this embodiment, C4 can be selected as a 30pF ceramic capacitor, the resonant frequency point of the 30pF ceramic capacitor is about 1.67GHz, and the impedance at the resonant frequency point is about 89mΩ, which just covers the interference frequency of 1GHz to 1.667GHz when the minimum discharge period of contact discharge is 0.6ns to 1ns. Because the impedance of the ceramic capacitor is the smallest at the resonant point, it shows the characteristics of resistance at this time, and its absorption effect is the best at the resonant point. That is, the 30pF ceramic capacitor can absorb the interference frequency band of 1GHz to 1.667GHz contact discharge within the working bandwidth.

[0192] C5 can be selected as a 100nF ceramic capacitor. The resonant frequency of the 100nF ceramic capacitor is about 38MHz, and the impedance at the resonant frequency is about 34mΩ, which just covers the interference frequency of 33.33MHz when the discharge period of contact discharge is 30ns. Because the impedance of the ceramic capacitor is the smallest at the resonant point, it exhibits the characteristics of a resistor, and its absorption effect is best at the resonant point.

[0193] C6 can be selected as a 1μF ceramic capacitor. The resonant frequency of a 1μF ceramic capacitor is about 13MHz, and the impedance at the resonant frequency is about 15mΩ, which just covers the interference frequency of 16.67MHz when the discharge period of contact discharge is 60ns. Because the impedance of the ceramic capacitor is the smallest at the resonant point, it exhibits the characteristics of a resistor, and its absorption effect is best at the resonant point.

[0194] C7 can be selected as a tantalum electrolytic capacitor, aluminum electrolytic capacitor, aluminum solid capacitor, or tantalum solid capacitor with a "U"-shaped impedance frequency characteristic curve (wide operating bandwidth), which is used to meet the minimum capacity for absorbing 90% of the charge in the electrostatic gun. At the same time, the resonant frequency point of the 100nF ceramic capacitor is about 38MHz, which can cover the interference frequency of 33.33MHz when the discharge period of contact discharge is 30ns. That is, the static charge generated by the contact discharge with an interference frequency of 1GHz to 1.667GHz at 0.6ns to 1ns is coupled to the PCB ground copper foil or PCB ground line 23 by C4 (30pF ceramic capacitor), and is stored on the two plates of C4, and is discharged to C5, C6, C7, and R2 at both ends of C4 in parallel; the static charge generated by the contact discharge with an interference frequency of 33.33MHz at a period of 30ns is coupled to the PCB ground copper foil or PCB ground line 23 by C5 (100nF ceramic capacitor), and is stored on the two plates of C5, and is discharged to C4, C6, C7, and R2 at both ends of C5 in parallel, with a minimum period of The static charge generated by the contact discharge of the interference frequency of 16.67MHz at 60ns is coupled to the PCB copper foil or PCB ground line 23 by C6 (1μF ceramic capacitor), and is stored on the two plates of C6, and discharged to C4, C5, C7, and R2 at both ends of C6 in parallel; C7 has a large capacitance, large ESR, and large ESL, and is only used as a storage capacitor. C7 can also be omitted as an alternative capacitor because the capacitance of C6 has met the minimum capacity to absorb 90% of the charge in the electrostatic gun; R2 has a very large resistance and has almost no effect on high-voltage and high-current discharge. It is just a long-term discharge loss component, and the power loss generated is calculated as follows: P = I 2 R, where I is the current flowing through R2.

[0195] Fig.13 is the equivalent model of the capacitor. Please refer to Fig.13, an ideal capacitor has zero dielectric loss, no leakage, zero distributed inductance, consistent frequency characteristics, and can output currents that tend to infinity, so it can be fully charged when the current tends to zero. Ideal capacitors do not exist. Actual capacitors consist of equivalent series resistance ESR (R11), equivalent series inductance (ESL) L11, and capacitor C11. They are caused by problems in the production process and the size of the package, such as the parasitic inductance generated by the pin leads (that is, the series equivalent inductance ESL). Since all substances are not superconductors, they have impedance. Static electricity will produce spikes in different frequency bands during the discharge process (such as air discharge and contact discharge). The spikes in different frequency bands must be absorbed by capacitors at different resonance points. That is, the static electricity spikes in different frequency bands will charge the capacitors at different resonance points at the first time, and at the same time, each capacitor must discharge the capacitors at other resonance points. The charging and discharging response speed of a capacitor is related to the ESR (equivalent series resistance) and ESL (equivalent series inductance) of the capacitor. After many experiments, we have come to the conclusion that the higher the frequency band of static noise, the smaller the ESL of the capacitor is required, and the ESR requirement of the capacitor is not high; the lower the frequency band of static noise, the smaller the ESR of the capacitor is required, and the ESL requirement of the capacitor is not high.

[0196] For the interference frequency 16.67MHz when the discharge cycle of contact discharge is 60ns, it corresponds to 1μF ceramic capacitor (the resonant frequency point is about 13MHz, and the impedance at the resonant frequency point is about 15mΩ). The interference of 16.67MHz frequency is low frequency. The most important factor affecting the charging and discharging speed of 1μF ceramic capacitor is the ESR of the capacitor, and the ESL of the capacitor is not the main factor. It is required that the smaller the ESR of 1μF ceramic capacitor is, the better the absorption effect of the interference frequency 16.67MHz when the discharge cycle of contact discharge is 60ns.

[0197] For the interference frequency of 33.33MHz when the discharge cycle of contact discharge is 30ns, it corresponds to a 100nF ceramic capacitor (the resonant frequency point is about 38MHz, and the impedance of the resonant frequency point is about 34mΩ). The interference of 33.33MHz frequency belongs to medium and low frequency noise. The main factor affecting the charging and discharging speed of the 100nF ceramic capacitor is the ESR of the capacitor, but ESL is also a secondary factor. The smaller the ESR of the 100nF ceramic capacitor, the better the absorption effect of the interference frequency of 33.33MHz when the discharge cycle of contact discharge is 30ns. At the same time, the ESL of the 100nF ceramic capacitor should also be paid attention to.

[0198] For the interference frequency of 1GHz~1.667GHz when the discharge period of contact discharge is 0.6ns~1ns, it corresponds to a 30pF ceramic capacitor (the resonant frequency point is about 1.67GHz, and the impedance at the resonant frequency point is about 89mΩ). The interference of 1GHz~1.667GHz frequency is high-frequency noise. The most important factor affecting the charging and discharging speed of the 30pF ceramic capacitor is the ESL of the capacitor, and ESR is not the key point. Therefore, the smaller the ESL of the 30pF ceramic capacitor, the better the absorption effect of the interference frequency of 1GHz~1.667GHz when the discharge period of contact discharge is 0.6ns~1ns.

[0199] Figure 14-Figure 20 This is the impedance frequency curve of ceramic capacitors with different capacitance values. Please refer to Figure 14-Figure 20 , the impedance frequency characteristic curve of ceramic capacitors is "V" shaped. Fig.14 The impedance frequency curve of a 10pF ceramic capacitor is given. The lowest point of the impedance frequency curve represents the resonant frequency. The resonant frequency of a 10pF ceramic capacitor is approximately 2.8GHz, and the impedance at the resonant frequency is approximately 400mΩ, at which point the impedance is minimum. Before the resonant point, the capacitor is capacitive, and beyond the resonant point, the capacitor gradually becomes inductive. Fig.15 The impedance frequency curve of a 30pF ceramic capacitor is given. The resonant frequency point of the 30pF ceramic capacitor is about 1.56GHz, and the impedance at the resonant frequency point is about 89mΩ, at which point the impedance is minimum. Before the resonance point, it is capacitive, and beyond the resonance point, the capacitor gradually becomes inductive. Fig.16 The impedance frequency curve of a 100pF ceramic capacitor is given. The resonant frequency point of the 100pF ceramic capacitor is about 1.25GHz, and the impedance at the resonant frequency point is about 89mΩ, at which point the impedance is minimum. Before the resonance point, it is capacitive, and beyond the resonance point, the capacitor gradually becomes inductive. Fig.17 The impedance frequency curve of a 1nF ceramic capacitor is given. The resonant frequency point of a 1nF ceramic capacitor is approximately 420MHz, and the impedance at the resonant frequency point is approximately 280mΩ, at which point the impedance is minimum. Before the resonance point, it is capacitive, and beyond the resonance point, the capacitor gradually becomes inductive. Fig.18 The impedance frequency curve of a 10nF ceramic capacitor is given. The resonant frequency point of the 10nF ceramic capacitor is about 85MHz, and the impedance at the resonant frequency point is about 15mΩ, at which point the impedance is minimum. Before the resonance point, it is capacitive, and beyond the resonance point, the capacitance gradually becomes inductive. Fig.19 The impedance frequency curve of 100nF ceramic capacitor is given. The resonant frequency point of 100nF ceramic capacitor is about 38MHz, and the impedance at the resonant frequency point is about 34mΩ, at which time the impedance is minimum; before the resonance point, it is capacitive, and beyond the resonance point, the capacitance gradually becomes inductive. Fig. 20The impedance frequency curve of a 1μF ceramic capacitor is given. The resonant frequency of a 1μF ceramic capacitor is about 13MHz, and the impedance at the resonant frequency is about 15mΩ, at which point the impedance is minimum; before the resonance point, it is capacitive, and beyond the resonance point, the capacitor gradually becomes inductive.

[0200] Fig.21 This is the impedance frequency curve of 150μF tantalum capacitor. Please refer to Fig.21 , the impedance frequency characteristic curve of 150μF tantalum capacitor is "U" shaped, and the working bandwidth range of the resonance point is relatively large. As can be seen from the figure, its impedance is 30.5mΩ between 100kHz and 1MHz, and its ESR is about 60mΩ to 70mΩ between 10kHz and 10MHz, the lowest ESR can reach 28.6mΩ, and the ESL is about 2.4nH.

[0201] Fig. 22 A schematic diagram of an electrostatic protection circuit provided in another embodiment of the present application; please refer to Fig. 22 ,and Figure 7 Compared with the circuit shown in the figure, the difference of this embodiment is that Figure 7 The triangle tube protector VD2 (the second electrostatic protector VD2) in the Fig. 22 There are two discrete diodes: VD4 and VD5, the anode A of diode VD5 and the cathode K of diode VD4 are electrically connected to the signal line 300; the anode A of diode VD4 is electrically connected to the power supply voltage (VCC) 410, and the cathode K of diode VD5 is connected to the PCB ground copper foil or the PCB ground line 23; if the voltage drop of diodes VD4 and VD5 is 0.7V (such as silicon tube), the clamping voltage of signal line 300 is between -0.7V and VCC+0.7V. When a positive voltage of 2kV to 8kV is injected into the input / output interface 100 for contact discharge, the clamping voltage of the signal line 300 is between 0V and VCC+0.7V, and the subsequent circuits such as the protection C2, R1, and the protected component 200 will not be damaged, and functional abnormalities are not likely to occur. When a negative voltage of 2kV to 8kV is injected into the input / output interface 100 for contact discharge, the clamping voltage of the signal line 300 is between -0.7V and 0V, and the subsequent circuits such as the protection C2, R1, and the protected component 200 will not be damaged, and functional abnormalities are not likely to occur.

[0202] If the voltage drop of diodes VD4 and VD5 is 0.3V (e.g., germanium tube), the clamping voltage of signal line 300 is between -0.3V and VCC+0.3V. When a positive voltage of 2kV to 8kV is injected into the input / output interface 100 for contact discharge, the clamping voltage of signal line 300 is between 0V and VCC+0.3V, and the subsequent circuits such as protection C2, R1, and protected component 200 will not be damaged, and will not easily cause functional abnormalities. When a negative voltage of 2kV to 8kV is injected into the input / output interface 100 for contact discharge, the clamping voltage of signal line 300 is between -0.3V and 0V, and the subsequent circuits such as protection C2, R1, and protected component 200 will not be damaged, and will not easily cause functional abnormalities.

[0203] Whether the diodes VD4 and VD5 are silicon tubes or germanium tubes is determined according to the actual application. The principle is that the voltage drop of the diodes VD4 and VD5 should slightly exceed the working level of the signal line 300. If the voltage drop of the diodes VD4 and VD5 is less than the working level threshold of the signal line 300, the signal of the signal line 300 will be "clipped". If the voltage drop of the diodes VD4 and VD5 is much larger than the working level threshold of the signal line 300, a higher electrostatic residual voltage will be injected into C2, R1, and the protected component 200, resulting in abnormal function or damage of the subsequent circuits.

[0204] Fig.23 A schematic diagram of an electrostatic protection circuit provided in another embodiment of the present application; please refer to Fig.23 ,and Fig. 22 Compared with the circuit shown in the figure, the difference of this embodiment is that Fig. 22 The cathode K of the middle diode VD5 is connected to the PCB ground copper foil or the PCB ground wire 23, that is, the cathode K of the diode VD4 and the anode A of the diode VD5 are connected in parallel and then electrically connected to the signal line 300, and the anode A of the diode VD4 and the cathode K of the diode VD5 are connected in parallel and then electrically connected to the PCB ground copper foil or the PCB ground wire 23.

[0205] If the voltage drop of diodes VD4 and VD5 is 0.7V (e.g., silicon tube), the clamping voltage of signal line 300 is between -0.7V and 0.7V. When a positive voltage of 2kV to 8kV is injected into the input / output interface 100 for contact discharge, the clamping voltage of signal line 300 is between 0V and 0.7V, and the subsequent circuits such as protection C2, R1, and protected component 200 will not be damaged, and it is not easy to cause functional abnormalities. When a negative voltage of 2kV to 8kV is injected into the input / output interface 100 for contact discharge, the clamping voltage of signal line 300 is between -0.7V and 0V, and the subsequent circuits such as protection C2, R1, and protected component 200 will not be damaged, and it is not easy to cause functional abnormalities.

[0206] If the voltage drop of diodes VD4 and VD5 is 0.3V (e.g., germanium tube), the clamping voltage of signal line 300 is between -0.3V and 0.3V. When a positive voltage of 2kV to 8kV is injected into the input / output interface 100 for contact discharge, the clamping voltage of signal line 300 is between 0V and 0.3V, and the subsequent circuits such as protection C2, R1, and protected component 200 will not be damaged, and it is not easy to cause functional abnormalities. When a negative voltage of 2kV to 8kV is injected into the input / output interface 100 for contact discharge, the clamping voltage of signal line 300 is between -0.3V and 0V, and the subsequent circuits such as protection C2, R1, and protected component 200 will not be damaged, and it is not easy to cause functional abnormalities.

[0207] In addition, the second electrostatic protector VD2 can be a silicon tube or a germanium tube, but it must be a device with a higher switching speed, so that the response speed of the second electrostatic protector can catch up with the response speed of 0.6ns electrostatic discharge. The second electrostatic protector VD2 can also be an ESD electrostatic diode, a TVS diode, a switching diode, a TSS diode, a varistor, a gas discharge tube, a voltage regulator diode, and an ESD electrostatic diode is preferred.

[0208] Fig.24 This is a frequency characteristic curve of POC inductance (power over coaxial cable inductance). Please refer to Fig.24 The resonance point of the inductor of this embodiment is around 116MHz, and the impedance of the inductor at the resonance point is the highest, about 20kΩ; the impedance around 1.05GHz is about 1kΩ, that is, the POC inductor will show a higher impedance in the contact discharge electrostatic interference frequency band, that is, the POC inductor will show a higher impedance in the contact discharge electrostatic interference frequency band of 16.67MHz to 1.667GHz. If Figure 7 , Figure 8 , Fig. 9 , Fig. 22 , Fig.23 The same effect can be achieved by replacing the magnetic bead L1 with an inductor. It should be noted that POC inductors are only suitable for transmitting low-frequency or low-speed signals, and are not suitable for transmitting high-speed or high-frequency signals, so as to avoid excessive impedance of POC inductors when transmitting high-speed or high-frequency signals, resulting in excessive insertion loss and impedance jump of high-speed or high-frequency signals, which will cause distortion of signal quality.

[0209] Fig.25 This is a schematic diagram of an electrostatic protection circuit provided by another embodiment of the present application. Fig.25 ,and Figure 7 The difference between the electrostatic protection circuit shown in the figure is that in this embodiment, Figure 7The first resistor R1 in the circuit is removed, that is, the protected component 200 is directly connected to the second pin of the magnetic bead L1 and the third pin of the second electrostatic protector VD2 through the signal line 300, and the other parts of the circuit are connected to the Figure 7 The circuit shown is the same as Figure 7 In comparison, this embodiment can save a resistor (first resistor R1), further reducing the cost and saving PCB board space, which is very practical in high-density PCB boards. At the same time, it can reduce the loss of the first resistor R1 on the signal transmission line 300. The functions and effects of the first electrostatic protector VD1 and the first capacitor C1, the magnetic bead L1, the second electrostatic protector VD2, the second capacitor C2, and the second resistor R2 are similar to Figure 7 It is the same, so I won’t repeat the description.

[0210] Fig.26 This is a schematic diagram of an electrostatic protection circuit provided by another embodiment of the present application. Fig.26 ,and Fig.25 The difference between the electrostatic protection circuit shown in the figure is that in this embodiment, Fig.25 The second capacitor C2 in the circuit is removed, that is, the protected component 200 is directly connected to the second foot of the magnetic bead L1 and the third foot of the second electrostatic protector VD2 through the signal line 300, and the other parts of the circuit are connected to the Fig.25 The circuit shown is the same as Fig.25 In comparison, this embodiment can save a capacitor (second capacitor C2), further reducing the cost and saving PCB board space, which is very practical in high-density PCB boards. At the same time, it can reduce the impedance of the second capacitor C2 to the low-frequency signal in the signal line 300, that is, after removing the second capacitor C2, an extremely low frequency signal or even a DC signal can be transmitted on the signal line 300 / signal line 303. The functions and effects of the first electrostatic protector VD1, the first capacitor C1, the magnetic bead L1, and the second electrostatic protector VD2 in this embodiment are similar to those in the embodiment of FIG. Fig.25 The scheme in is the same and will not be described again.

[0211] Fig. 27 This is a schematic diagram of an electrostatic protection circuit provided by another embodiment of the present application. Fig. 27 ,and Fig.26 The difference between the electrostatic protection circuit shown in the figure is that in this embodiment, Fig.26 The second electrostatic protector VD2 in the circuit is removed, that is, the second foot of the magnetic bead L1 is connected to the input / output interface 100, and the other parts of the circuit are connected to the Fig.26 The circuit shown is the same as Fig.26In comparison, this embodiment can save an electrostatic protector (the second electrostatic protector VD2), further reducing the cost and saving PCB board space, which is very practical in high-density PCB boards. Similarly, it can be used for extremely low frequency signals on signal line 300 / signal line 303, or even DC signals. The functions and effects of the first electrostatic protector VD1, the first capacitor C1, and the second resistor R2 in this embodiment are similar to those in FIG. Fig.26 The scheme in is the same and will not be described again.

[0212] Fig.28 This is a schematic diagram of an electrostatic protection circuit provided by another embodiment of the present application. Fig.28 ,and Fig. 27 The difference between the electrostatic protection circuit shown in the figure is that in this embodiment, Fig. 27 The magnetic bead L1 in the circuit is removed, that is, the protected component 200 is directly connected to the input / output interface 100 through the signal line 310, and the other parts of the circuit are connected to the Fig. 27 The rest of the circuit is the same as Fig. 27 The circuit shown is the same as Fig. 27 Compared with the above scheme, this embodiment can save a magnetic bead (magnetic bead L1), further reducing the cost and saving PCB board space. This is very practical in high-density PCB boards. It can transmit very low-frequency signals or even DC signals on signal line 300 / signal line 303, as well as high-speed signals and high-frequency signals (such as radio frequency signals). The functions and effects of the first electrostatic protector VD1, the second resistor R2, and the first capacitor C1 in this embodiment are similar to those in the above scheme. Fig. 27 The scheme in is the same and will not be described again.

[0213] Fig.29 This is a schematic diagram of an electrostatic protection circuit provided by another embodiment of the present application. Fig.29 ,and Figure 7 The difference between the electrostatic protection circuit shown in the figure is that in this embodiment, Figure 7 The second electrostatic protector VD2 is removed, and the rest of the circuit is the same as Figure 7 The circuit shown is the same as Figure 7 Compared with the above scheme, this embodiment can save an electrostatic protector (the second electrostatic protector VD2), further reducing the cost and saving PCB board space. This is very practical in high-density PCB boards. It can be used for extremely low frequency signals on signal line 300 / signal line 303, or even DC signals. The functions and effects of the first resistor R1, the second capacitor C2, the first capacitor C1, the magnetic bead L1, the second resistor R2, and the first electrostatic protector VD1 in this embodiment are similar to those in the above scheme. Figure 7 The scheme in is the same and will not be described again.

[0214] Fig.30This is a schematic diagram of an electrostatic protection circuit provided by another embodiment of the present application. Fig.30 ,and Fig.29 The difference between the electrostatic protection circuit shown in the figure is that in this embodiment, Fig.29 The second capacitor C2 and the magnetic bead L1 are removed, that is, the first pin of the first resistor R1 is connected to the protected component 200, and the second pin of the first resistor R1 is connected to the first pin of the first electrostatic protector VD1 through the signal line 303. The rest of the circuit is connected to Fig.29 The circuit shown is the same as Fig.29 Compared with the above scheme, this embodiment can save a capacitor (second capacitor C2) and a magnetic bead (magnetic bead L1), further reducing the cost and saving PCB board space. This is very practical in high-density PCB boards. It can transmit very low-frequency signals or even DC signals on signal line 300 / signal line 303, as well as high-speed signals and high-frequency signals (such as radio frequency signals). The functions and effects of the first resistor R1, the first capacitor C1, the second resistor R2, and the first electrostatic protector VD1 in this embodiment are similar to those in the above scheme. Fig.29 The scheme in is the same and will not be described again.

[0215] Fig.31 This is a schematic diagram of an electrostatic protection circuit provided by another embodiment of the present application. Fig.31 ,and Figure 7 The difference between the electrostatic protection circuit shown in the figure is that in this embodiment, Figure 7 The second capacitor C2 in the circuit is removed, that is, the first resistor R1 is directly connected to the second pin of the magnetic bead L1 and the third pin of the second electrostatic protector VD2 through the signal line 300, and the other parts of the circuit are connected to the Figure 7 The circuit shown is the same as Figure 7 In comparison, this embodiment can save a capacitor (second capacitor C2), further reducing the cost and saving PCB board space, which is very practical in high-density PCB boards. Similarly, it can be used for extremely low frequency signals on signal line 300 / signal line 303, or even DC signals. The functions and effects of the first electrostatic protector VD1 and the first capacitor C1, the magnetic bead L1, the second electrostatic protector VD2, the first resistor R1, and the second resistor R2 are similar to Figure 7 It is the same, so I won’t repeat the description.

[0216] Fig.40 This is a schematic diagram of an electrostatic protection circuit provided by another embodiment of the present application. Fig.40 ,and Fig.23 The difference between the electrostatic protection circuit shown in the figure is that in this embodiment, Fig.23The diode VD4 and the diode VD5 in the second electrostatic protector are replaced with the bidirectional electrostatic protector VD2. The breakdown threshold voltage of the bidirectional electrostatic protector VD2 (the second electrostatic protector) is slightly higher than the working voltage of the signal line 300, and the first electrostatic protector VD1 is slightly higher than the working voltage of the signal line 303, to avoid the abnormality of the first electrostatic protector VD1 and the bidirectional electrostatic protector VD2 (the second electrostatic protector) when the signal lines 300 and 303 are working normally, causing the signal to be "clipped" and cause signal distortion. The first resistor R1 is removed, that is, the bidirectional electrostatic protector VD2 is directly connected to the second pin of the magnetic bead L1 and the second pin of the second capacitor C2 through the signal line 300, and the other parts of the circuit are the same. Fig.23 The circuit shown is the same as Fig.23 In comparison, this embodiment can save one of the diodes in the second electrostatic protector (for example, diode VD4 or diode VD5), further reducing the cost and saving PCB board space, which is very practical in high-density PCB boards. The functions and effects of the first electrostatic protector VD1 and the first capacitor C1, the magnetic bead L1, the second capacitor C2, and the second resistor R2 are similar to Fig.23 It is the same, so I won’t repeat the description.

[0217] Fig.32 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application; Fig.33 for Fig.32 Please refer to the partial cross-sectional view of Fig.32 and Fig.33 , Fig.32 yes Fig.28 In a specific application example of a router product, the protected component 200 includes a Wifi chip 157, a balun circuit component 171, a Wifi chip matching component 153, a FEM chip 176, a Wifi RF filter 152, a Wifi RF filter matching component 151, and an antenna matching component 173. The Wifi chip 157 is connected to the balun circuit component 171 via an RF trace 172; the balun circuit component 171 is connected to the Wifi chip matching component 153 via an RF trace 154; the Wifi chip matching component 153 is connected to the FEM chip 176 via an RF trace 155; the FEM chip 176 is connected to the Wifi RF filter 152 via an RF trace 175; the Wifi RF filter 152 is connected to the Wifi RF filter matching component 151 via an RF trace 156; the Wifi RF filter matching component 151 is connected to the antenna matching component 173 via an RF trace 174; the antenna matching component 173 is connected via a signal line 310 (at Fig.32 The signal line 310 in the figure is a radio frequency line) and the first pin of the first electrostatic protector VD1, the input / output interface 100 (in Fig.32The input / output interface 100 in the router is an SMA female connector). The router uses an external antenna 184, which protrudes outside the product. If the SMA female connector 100 (input / output interface 100) is exposed outside the product, 4kV to 8kV contact discharge is required. There is a gap between the SMA female connector 100 (input / output interface 100) and the external antenna 184 interface: for example, there is a gap between the external antenna rotation interface 181 and the SMA female connector 100 (input / output interface 100), and there is a gap between the rotation interface 181 of the external antenna 184 and the plastic shell 185 (with an antenna cable 182 built in). Air discharge is required at the gap position of the product, which will introduce air discharge into the external antenna 184. The first electrostatic protector VD1, the first capacitor C1, and the second resistor R2 should be as close to the SMA female base 100 as possible, and the external antenna 184 should be introduced into the air discharge as much as possible. The static discharge caused by the signal line 300 is stored in the capacitor C1, and the antenna matching component 173 is as close to the first electrostatic protector VD1 and the input / output interface 100 (in Fig.32 The input / output interface 100 in the circuit is an SMA female connector). The SMA female connector 100 is welded to the PCB board 170 near the housing 180, that is, a hole 526 is opened in the housing 180 at the position of the SMA female connector 100 for installing the rotating interface 181 of the external antenna 184. If the housing 180 is a plastic shell, a gap will be generated by opening the hole 526 in the housing 180, and the SMA female connector 100 is made of metal material. If it can be clearly touched by human fingers, a 4kV to 8kV contact discharge is required. If it cannot be directly touched by human fingers, a 6kV to 15kV air discharge is required. At this time, whether it is a 4kV to 8kV contact discharge or a 6kV to 15kV air discharge, it will be discharged from the SMA female connector 100 to the signal line 300 (at Fig.32 The signal line 310 in the figure is a radio frequency line) and high voltage static electricity is injected.

[0218] If the electrostatic protection circuit composed of the first electrostatic protector VD1, the first capacitor C1, and the second resistor R2 is not added, the external antenna introduces air discharge through the signal line 300 (at Fig.32The signal line 310 in the figure is an RF trace) and is injected into the antenna matching component 173, resulting in abnormal Wifi RF signal function; the signal line 310 in the figure is an RF trace) and is injected into the antenna matching component 173, resulting in abnormal Wifi RF signal function; the signal line 310 in the figure is an RF trace 174 and is injected into the Wifi RF filter matching component 151, resulting in abnormal Wifi RF signal function; the signal line 310 in the figure is an RF trace 156 and is injected into the Wifi RF filter 152, resulting in abnormal Wifi RF signal function; the signal line 310 in the figure is an RF trace) and is injected into the antenna matching component 173, resulting in abnormal Wifi RF signal function; the signal line 310 in the figure is an RF trace) and is injected into the Wifi RF filter matching component 151 ... chip 157, resulting in abnormal Wifi RF signal function; even the Wifi RF filter matching component 151, the Wifi RF filter 152, the FEM chip 176, the Wifi chip matching component 153, the balun circuit component 171, and the Wifi chip 157 are all at risk of being permanently damaged by electrostatic disturbance, so in the input / output interface 100 (in Fig.32 The input / output interface 100 in the embodiment is an SMA female socket) and the antenna matching component 173 are added with a first electrostatic protector VD1, a first capacitor C1, and a second resistor R2 to form an electrostatic protection circuit, which can maximize the influence of static electricity brought by air discharge or contact discharge introduced from the external antenna 184 on the radio frequency signals in the Wifi RF filter matching component 151, the Wifi RF filter 152, the FEM chip 176, the Wifi chip matching component 153, the balun circuit component 171, and the Wifi chip 157 (such as packet loss, crash and other abnormal phenomena), and at the same time protect the Wifi RF filter matching component 151, the Wifi RF filter 152, the FEM chip 176, the Wifi chip matching component 153, the balun circuit component 171, and the Wifi chip 157 from being damaged by static electricity.

[0219] The plastic shell 185 of the external antenna 184 is provided with a radiator 183, and the radiator 183 is connected to the rotation interface 181 of the external antenna 184 through the antenna cable 182). After the external antenna rotation interface 181 (that is, the SMA male socket) is tightly combined with the SMA female socket in the PCB board 170 in the router, the RF signal modulated by the Wifi chip 157 is transmitted through the balun circuit component 171, the Wifi chip matching component 153, the FEM chip 176, the Wifi RF filter 152, the Wifi RF filter matching component 151, the antenna matching component 173, the SMA female socket 100 (in Fig.32 The input / output interface 100 in the embodiment is an SMA female connector) which resonates through an external antenna 184 to send radio wave signals to surrounding devices.

[0220] Taking a 4-layer PCB board as an example, the ground pin 503 of the Wifi chip 157 and the ground pin of the balun circuit component 171 ( Fig.32 and Fig.33 Not marked), Wifi external antenna rotation interface 181 chip matching component 153 ground pin ( Fig.32 and Fig.33 Not marked), ground pin of FEM chip 176 ( Fig.32 and Fig.33 Not marked), the ground pin of the Wifi RF filter 152, the ground pin of the Wifi RF filter matching component 151 ( Fig.32 and Fig.33 Not marked), the ground pin of the antenna matching component 173 ( Fig.32 and Fig.33 Not marked), the SMA female socket 100 is connected to the ground copper foil 514 of the TOP layer (top layer) 500, the ground copper foil 510 of the second layer, the ground copper foil 522 of the third layer, and the ground copper foil 513 of the BOTTOM layer (bottom layer) 501 through the ground holes 504, 505, 506, 507, 508, 509, and 520, respectively, to achieve connection with the PCB ground copper foil or the PCB ground wire 23 (referring to the ground copper foil of the entire board).

[0221] By adding an electrostatic protection circuit consisting of a first electrostatic protector VD1, a first capacitor C1, and a second resistor R2 between the antenna matching component 173 and the SMA female socket 100, the electrostatic absorption generated by the external antenna 184 can be stored in the first capacitor C1, instead of being directly discharged to the ground copper foil 514 of the TOP layer (top layer) 500, the ground copper foil 510 of the second layer, the ground copper foil 522 of the third layer, and the ground copper foil 513 of the BOTTOM layer (bottom layer) 501, causing static electricity to be injected into the ground pin 503 of the Wifi chip 157 and the ground pin (503) of the balun circuit component 171 through the ground holes 504, 505, 506, 507, 508, 509, and 520, respectively. Fig.32 and Fig.33 Not marked), Wifi chip matching component 153 ground pin ( Fig.32 and Fig.33 Not marked), ground pin of FEM chip 176 ( Fig.32 and Fig.33 Not marked), the ground pin of the Wifi RF filter 152, the ground pin of the Wifi RF filter matching component 151 ( Fig.32 and Fig.33 Not marked), the ground pin of the antenna matching component 173 ( Fig.32 and Fig.33The RF signal return path is disturbed by static electricity, which causes the RF signal in the Wifi chip 157, the balun circuit component 171, the Wifi chip matching component 153, the FEM chip 176, the Wifi RF filter 152, the Wifi RF filter matching component 151, the antenna matching component 173, and the SMA female socket 100 to work abnormally, such as the Wifi signal packet loss, freeze, and other abnormal phenomena.

[0222] In addition, the first electrostatic protector VD1 uses an ESD protection device with very small junction capacitance, for example, an ESD protection device of pF level. Fig.32 The junction capacitor C10 of the first electrostatic protector VD1 is connected in series with the first capacitor C1 and then connected in parallel to the signal line 310 (the signal line 310 is connected in parallel to the signal line 310). Fig.32 The equivalent capacitance C11 of the junction capacitance C10 of the first electrostatic protector VD1 and the first capacitor C1 in series is calculated as follows:

[0223]

[0224] That is, the equivalent capacitance C11 of the junction capacitance C10 of the first electrostatic protector VD1 connected in series with the first capacitor C1 is smaller than the junction capacitance C10 of the first electrostatic protector VD1, and C11 is also much smaller than the first capacitor C1. Therefore, as long as the first electrostatic protector VD1 selects a pF-level ESD protection device, the equivalent capacitance C11 of the junction capacitance C10 of the first electrostatic protector VD1 connected in series with the first capacitor C1 is smaller than the junction capacitance C10 of the first electrostatic protector VD1 alone. Therefore, adding an electrostatic protection circuit consisting of the first electrostatic protector VD1, the first capacitor C1, and the second resistor R2 between the antenna matching component 173 and the SMA female socket 100 does not affect the distributed parameters (distributed capacitance, distributed inductance) of the signal line 310, and will not affect the signal line 310 (at Fig.32 , Fig.33 The RF signal in the signal line 310 (the signal line 310 is an RF routing) causes the distributed capacitance to be too large, so it will not affect the impedance of the RF signal (if the distributed capacitance is too large, the impedance of the signal line 310 will be significantly lower). Because if the distributed parameters of the first electrostatic protector VD1 change (for example, the distributed capacitance becomes larger), the impedance of the signal line 310 will change (for example, the impedance will be lower than 50 ohms ± 5 ohms), which will cause the impedance of the RF signal in the signal line 310 to jump, resulting in a series of performance indicators such as VSWR (Voltage Standing Wave Ratio) and S11 (return loss) of the RF signal in the signal line 310 to deteriorate.

[0225] At the same time, since the threshold of the breakdown voltage of the first electrostatic protector VD1 slightly exceeds the swing amplitude of the RF signal in the signal line 310, when the external antenna 184 is injected into the signal line 310 through the SMA socket 100 without static electricity, the RF signal in the signal line 310 will not cause the first electrostatic protector VD1 to break down and conduct, so the first capacitor C1 does not affect the distributed capacitance in the signal line 310, that is, during normal operation, the first capacitor C1 does not affect the normal impedance of 50 ohms of the signal line 310.

[0226] refer to Fig.33 , SMA female socket 100 (in Fig.32 The input / output interface 100 in the circuit is an SMA female connector and is fixed by welding on the BOTTOM surface (bottom surface) of the PCB board 170. The first foot of the first electrostatic protector VD1 is welded to the pad 160 on the PCB board 170. The pad 160 is connected to the signal line 310 (on the Fig.32 , Fig.33 The signal line 310 is connected to the RF wiring, and the first foot and the pad 160 of the first electrostatic protector VD1 should be placed on the main channel of the signal line 310, so that the first electrostatic protector VD1 can quickly absorb the static electricity brought by the external antenna 184.

[0227] Wifi chip 157, RF trace 172, balun circuit component 171, RF trace 154, Wifi chip matching component 153, RF trace 155, FEM chip 176, RF trace 175, Wifi RF filter 152, RF trace 156, and Wifi RF filter matching component 151 need to be arranged inside the shielding cover 210, that is, the shielding cover 210 covers the Wifi chip 157, RF trace 172, balun circuit component 171, RF trace 154, Wifi chip matching component 153, RF trace 155, FEM chip 176, RF trace 175, Wifi RF filter 152, RF trace 156, and Wifi RF filter matching component 151 to prevent them from being exposed outside the shielding cover, resulting in excessive Wifi spurious signals. The antenna matching component 173 , the junction capacitor C10 of the electrostatic protector VD1 , the first capacitor C1 , the second resistor R2 , and the SMA female socket 100 need to be disposed outside the shielding cover 210 .

[0228] Fig.34 A schematic diagram of an electrostatic protection circuit provided in yet another embodiment of the present application; Fig.35 for Fig.34 Please refer to the partial cross-sectional view of Fig.34 and Fig.35 ,in Fig.34 yes Fig.28Specific application example in the vehicle-mounted device 802; the protected component 200 includes a Wifi chip 257 (with a built-in balun circuit component), a Wifi radio frequency filter 251, and an antenna matching component 258. The first electrostatic protector VD1, the first capacitor C1, and the second resistor R2 form an electrostatic protection circuit. The first pin of the first electrostatic protector VD1 is connected to the antenna matching component 258 and the input / output interface 100 (in Fig.34 and Fig.35 The input / output interface 100 is connected to the antenna feed point (exposed copper).

[0229] The Wifi chip 257 is connected to the Wifi RF filter 251 through the RF trace 254; the Wifi RF filter 251 is connected to the Wifi RF filter 251 through the signal line 310 ( Fig.34 and Fig.35 The signal line 310 in the figure is a radio frequency line) and the input / output interface 100 (in Fig.34 and Fig.35 The input / output interface 100 in the vehicle-mounted device 802 is connected to the feed point exposed copper of the antenna 526; the vehicle-mounted device 802 adopts a built-in PIFA antenna 526, and the radiator 166 of the PIFA antenna 526 is fixed on the bracket 528, and the spring 167 is led out from the radiator 166 of the PIFA antenna 526, and the contact 168 of the spring 167 is connected to the feed point exposed copper 100 in the PCB board 170 (in Fig.34 and Fig.35 The input / output interface 100 in the antenna feed point is exposed copper) to realize the contact between the PIFA antenna 526 and the signal line 310 (in Fig.34 and Fig.35 Since the radiator 166 of the PIFA antenna 526 is close to the inside of the plastic shell 165, and there is a gap on the outside of the plastic shell 165 at the position of the radiator 166 of the PIFA antenna 526, according to the Chinese 3C certification and the EU CE certification, the gap position of the plastic shell needs to be 6kV~15kV air discharge, so the static electricity generated by the air discharge near the PIFA antenna 526 is injected into the signal line 310 and the antenna matching component 258 through the contact 168 of the spring 167 and the exposed copper 100 of the antenna feed point. , RF trace 258, Wifi RF filter 251, RF trace 254, Wifi chip 257, will cause the RF signals in the signal line 310, antenna matching component 258, RF trace 258, Wifi RF filter 251, RF trace 254, and Wifi chip 257 to be interfered by static electricity, resulting in abnormal functions (such as Wifi signal packet loss, crash, etc.), and even damage to the antenna matching component, Wifi RF filter 251, and Wifi chip 257.

[0230] After adding the first electrostatic protector VD1, the first capacitor C1, and the second resistor R2 between the antenna matching component 258 and the input / output interface 100 to form an electrostatic protection circuit, the static electricity injected into the signal line 310 from the contact 168 of the spring 167 and the exposed copper 100 of the antenna feed point will be broken down and turned on by the first electrostatic protector VD1, injected into the first capacitor C1 for storage, and then slowly consumed through the second resistor R2.

[0231] By adding an electrostatic protection circuit consisting of a first electrostatic protector VD1, a first capacitor C1, and a second resistor R2 between the antenna matching component 258 and the antenna feed point exposed copper 100, the electrostatic absorption generated by the antenna feed point exposed copper 100 can be stored in the first capacitor C1, rather than being directly discharged to the ground copper foil 514 of the TOP layer (top layer) 500 of the PCB board 170, the ground copper foil 510 of the second layer, the ground copper foil 522 of the third layer, and the ground copper foil 513 of the BOTTOM layer (bottom layer) 501, that is, they are finally injected into the PCB ground copper foil or the PCB ground wire 23 (the ground copper foil 23 is the ground copper foil of the entire board in the PCB board), causing static electricity to be injected into the ground pin ( Fig.34 and Fig.35 Not marked), ground pin of Wifi RF filter 251 ( Fig.34 and Fig.35 The ground pin 527 of the Wifi chip 257 (not marked) and the like may cause the RF signal return path to be disturbed by static electricity, which may cause the RF signal in the Wifi chip 257, the Wifi RF filter 251, and the antenna matching component 258 to work abnormally, such as packet loss, freezing, and other abnormal phenomena of the Wifi signal.

[0232] Fig.36 This is a schematic diagram of an electrostatic protection circuit provided by another embodiment of the present application. Fig.36 , Fig.36 The application scenario in which the vehicle-mounted device 802 leads to a 5V external power cable 800 to supply power to the external device 801 is given. Fig.23 Compare, Fig.36 Replace the second electrostatic protector: diode VD4 and diode VD5 with electrostatic protector VD5 (preferably bidirectional ESD electrostatic diode, bidirectional TVS diode), connect pin 2 of electrostatic protector VD5 to PCB ground copper foil or PCB ground wire 23, and connect pin 1 of electrostatic protector VD5 to power line 300 ( Fig.23 The signal line is 300, and Fig.36 The difference is that the signal line is thinner, while the power line is thicker, and needs to meet the requirements of current flow and voltage drop.) At the same time, remove Fig.23 The first resistor R1 and the second capacitor C2 in Fig.23The magnetic bead L1 is replaced with the POC inductor L1. The 5V power is output from the power conversion component 200 and sent to the POC inductor L1 via the power line 300, and then to the POC inductor L1 via the power line 303 ( Fig.23 In the signal line 303, Fig.36 The power line 303 in the middle, the difference is that the signal line is thinner, while the power line is thicker, and needs to meet the requirements of current flow and voltage drop) and the first electrostatic protector VD1 + the first capacitor C1 + the second resistor R2 form an electrostatic protector circuit and send it to the pad 100 (in Fig.36 The input / output interface 100 in the embodiment is a soldering pad 100, the soldering pad 100 is soldered with an external power cable 800, and the external power cable 800 is led out to the outside of the vehicle-mounted device 802 to supply power to the external device 801. According to the Chinese G6.2B / T1762 standard (equivalent to the international standard IEC61000-4-2), a 4kV to 8kV contact discharge needs to be injected from the external power cable 800, and the vehicle-mounted device 802 cannot be abnormal. When the external power cable 800 is injected with 4kV-8kV contact discharge, the 4kV-8kV high-voltage static electricity generated from the external power cable 800, the pad 100, and the power line 303 will instantly break down the first electrostatic protector VD1, and most of the static electricity is stored in the two plates inside the first capacitor C1. The remaining part is rebounded back to the first electrostatic protector VD1 by the POC inductor L1, and the first electrostatic protector VD1 is broken down and stored in the two plates inside the first capacitor C1 by the first capacitor C1 again. Only a very small amount of static electricity passes through the POC inductor L1. When the residual voltage of the power line 300 exceeds the threshold voltage of the electrostatic protector VD5, the electrostatic protector VD5 is instantly broken down, and the residual voltage of the power line 300 is clamped near the threshold voltage of the second electrostatic protector VD5, protecting the power conversion component 200 from damage. At the same time, it can maintain the power line 300 near the threshold voltage of the electrostatic protector VD5, protecting the power supply voltage of other devices connected to the power line 300 from sudden abnormality, causing the vehicle-mounted device 802 to fail to work normally. The threshold voltage of the second electrostatic protector VD5 breakdown is slightly higher than that of the power line 300, and the threshold voltage of the first electrostatic protector VD1 breakdown is slightly higher than that of the power line 303, so as to avoid the second electrostatic protector VD5 and the first electrostatic protector VD1 from malfunctioning when the power conversion component 200 normally supplies power to the external device 801 through the external power cable 800, resulting in abnormal external power supply. Since the power lines 303 and 300 transmit direct current, there is no special requirement for the junction capacitance of the second electrostatic protector VD5 and the first electrostatic protector VD1, which does not affect the normal operation of the power conversion component 200 transmitting power to the external device 801 through the external power cable 800.

[0233] for Figure 7 to Figure 9 , Fig.12 , Fig. 22 , Fig.23 , Figure 25 to Figure 35 , if in Figure 7 to Figure 9 , Fig.12 , Fig. 22 , Fig.23 , Figure 25 to Figure 27 The signal line (eg, Figure 7 The signal line 300 and the signal line 303 in Fig.32 When the signal line 310 in the circuit needs to transmit high-speed signals (such as USB signals, HDMI signals, PCIE signals, DVI signals, LDVS signals, etc.) and high-frequency signals (such as Wifi radio frequency signals, LTE radio frequency signals, Bluetooth radio frequency signals, etc.), the junction capacitance of the first electrostatic protector VD1 must be low. For example, USB2.0 requires that the junction capacitance of the first electrostatic protector VD1 be selected to be less than 3pF, and USB3.0 requires that the junction capacitance of the first electrostatic protector VD1 be selected to be less than 0.3pF.

[0234] If in Figure 7 to Figure 9 , Fig.11 , Fig.12 , Fig. 22 , Fig.23 , Fig.25 , Fig.26 , Fig.31 , Fig.36 , Fig.40 The signal line (eg, Figure 7 When the signal lines 300 and signal lines 303 in the circuit (such as signal lines 300 and signal lines 303) transmit high-speed signals (such as USB signals, HDMI signals, PCIE signals, DVI signals, etc.) and high-frequency signals (such as Wifi radio frequency signals, LTE radio frequency signals, Bluetooth radio frequency signals, etc.), the junction capacitance of the second electrostatic protector VD2 must be low. For example, USB2.0 requires that the junction capacitance of the second electrostatic protector VD2 be selected to be less than 3pF, and USB3.0 requires that the junction capacitance of the second electrostatic protector VD2 be selected to be less than 0.3pF.

[0235] In summary, Figure 7 to Figure 9 , Fig.11 , Fig.12 , Fig. 22 , Fig.23 , Figure 25 to Figure 32 , Fig.34 , Fig.36 , Fig.40 The higher the rate or frequency of the signal (including power, which is a DC signal) transmitted in the signal lines 300 , 310 , and 303 , the smaller the junction capacitance of the first electrostatic protector VD1 and the second electrostatic protector VD2 is required to be.

[0236] It should be noted that if Figure 7 to Figure 9 , Fig.11 , Fig.12 , Fig. 22 , Fig.23 , Figure 25 to Figure 27 , Fig.29 , Fig.32 , Fig.36 , Fig.40 When transmitting differential signals (such as differential line signals of interfaces such as USB2.0, USB3.0, HDMI, LVDS, MIPI, PCIE, etc.), the magnetic bead L1 can be changed to a common-mode inductor L1 to filter out the noise generated in the PCB board (such as noise generated by the protected component 200, etc.) to avoid excessive EMI radiation in electronic equipment.

[0237] It should be noted that Figure 7 to Figure 9 , Fig.11 , Fig.12 , Fig.23 , Figure 26 to Figure 36 , Fig.39 , Fig.40 In the figure, only PCB ground copper foil or PCB ground wire 23 is used as an example for grounding, and the specific form of grounding is not limited. For example, it can be any one of PCB ground copper foil, PCB ground wire, negative pole of battery, secondary output terminal ground of AC-DC adapter, chassis ground, earth, etc. Fig.37 A specific implementation method of PCB ground wire is given. Fig.38 A specific implementation of PCB copper foil is given.

[0238] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0239] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0240] It should be noted that in the description of this application, the terms "first" and "second" are only used to facilitate the description of different components, and cannot be understood as indicating or implying a sequential relationship, relative importance, or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0241] The various embodiments or implementation methods in the present application are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0242] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In the present application, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0243] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrostatic protection circuit, arranged on a signal line between an input / output interface of an electronic device and a protected component, characterized in that: The electrostatic protection circuit comprises: a first electrostatic protector, wherein a first end of the first electrostatic protector is connected to the input / output interface, and the first end of the first electrostatic protector is also connected to the protected component; a second end of the first electrostatic protector is connected to a first end of a first capacitor, and a second end of the first capacitor is grounded; A first electronic component is further connected in series between the protected component and the input / output interface, a second capacitor is further connected in series between the second end of the first electronic component and the protected component, a first end of the second capacitor is connected to the protected component, and a second end of the second capacitor is connected to the second end of the first electronic component; A first resistor is further connected in series between the first end of the second capacitor and the protected component, the first end of the first resistor is connected to the protected component, and the second end of the first resistor is connected to the first end of the second capacitor; A second electrostatic protector is further provided between the first electronic component and the second capacitor, a third end of the second electrostatic protector is connected between the first electronic component and the second capacitor, and a first end of the second electrostatic protector is grounded.

2. The electrostatic protection circuit according to claim 1, characterized in that: The first electrostatic protector includes one or more of an ESD electrostatic diode, a TVS diode, a switching diode, a TSS diode, a voltage-stabilizing diode, a varistor and a gas discharge tube.

3. The electrostatic protection circuit according to claim 1, characterized in that: The first end of the first electronic component is connected to the input / output interface, and the second end of the first electronic component is connected to the protected component; the first end of the first electrostatic protector is connected between the input / output interface and the first end of the first electronic component.

4. The electrostatic protection circuit according to claim 3, characterized in that: The first electronic component includes a magnetic bead, an inductor and / or a resistor.

5. The electrostatic protection circuit according to claim 4, characterized in that: The first end of the first capacitor is also connected to the first end of the power consumption element, and the second end of the power consumption element is grounded.

6. The electrostatic protection circuit according to claim 5, characterized in that: The power consumption element includes a second resistor, and the resistance of the second resistor is greater than 20 kΩ.

7. The electrostatic protection circuit according to claim 5, characterized in that: The electronic device is also provided with a power circuit, and the power circuit includes a power input terminal and a power output terminal; The second electrostatic protector is a triangular tube protector, the second electrostatic protector includes a first diode and a second diode, the cathode of the first diode is connected to the anode of the second diode, the anode of the first diode is grounded through the first end of the second electrostatic protector, the cathode of the second diode is connected to the power input end or the power output end through the second end of the second electrostatic protector, the third end of the second electrostatic protector is arranged between the cathode of the first diode and the anode of the second diode, and the third end of the second electrostatic protector is connected to the second end of the first electronic component; Alternatively, the second electrostatic protector includes a third diode and a fourth diode, the cathode of the third diode is connected to the anode of the fourth diode, the anode of the third diode is grounded through the first end of the second electrostatic protector, the cathode of the fourth diode is connected to the power input end or the power output end through the second end of the second electrostatic protector, the third end of the second electrostatic protector is arranged between the cathode of the third diode and the anode of the fourth diode, and the third end of the second electrostatic protector is connected to the second end of the first electronic component.

8. The electrostatic protection circuit according to claim 5, characterized in that: The electronic device has a built-in battery, the battery includes a positive electrode and a negative electrode, and the negative electrode of the battery is grounded; The second electrostatic protector is a triangular tube protector, the second electrostatic protector includes a first diode and a second diode, the cathode of the first diode is connected to the anode of the second diode, the anode of the first diode is grounded through the first end of the second electrostatic protector, the cathode of the second diode is connected to the positive electrode of the battery through the second end of the second electrostatic protector, the third end of the second electrostatic protector is arranged between the cathode of the first diode and the anode of the second diode, and the third end of the second electrostatic protector is connected to the second end of the first electronic component; Alternatively, the second electrostatic protector includes a third diode and a fourth diode, the cathode of the third diode is connected to the anode of the fourth diode, the anode of the third diode is grounded through the first end of the second electrostatic protector, the cathode of the fourth diode is connected to the positive electrode of the battery through the second end of the second electrostatic protector, the third end of the second electrostatic protector is arranged between the cathode of the third diode and the anode of the fourth diode, and the third end of the second electrostatic protector is connected to the second end of the first electronic component.

9. The electrostatic protection circuit according to claim 5, characterized in that: The second electrostatic protector is a triangular tube protector, the second electrostatic protector includes a first diode and a second diode, the cathode of the first diode is connected to the anode of the second diode, the anode of the first diode is grounded through the first end of the second electrostatic protector, the cathode of the second diode is grounded through the second end of the second electrostatic protector, the third end of the second electrostatic protector is arranged between the cathode of the first diode and the anode of the second diode, and the third end of the second electrostatic protector is connected to the second end of the first electronic component; Alternatively, the second electrostatic protector includes a third diode and a fourth diode, the cathode of the third diode is connected to the anode of the fourth diode, the anode of the third diode is grounded through the first end of the second electrostatic protector, the cathode of the fourth diode is grounded through the second end of the second electrostatic protector, the third end of the second electrostatic protector is arranged between the cathode of the third diode and the anode of the fourth diode, and the third end of the second electrostatic protector is connected to the second end of the first electronic component.

10. The electrostatic protection circuit according to any one of claims 7 to 9, characterized in that: The second end of the second electrostatic protector is also connected to the first end of the third capacitor, and the second end of the third capacitor is grounded.

11. The electrostatic protection circuit according to claim 10, characterized in that: The power supply voltage of the electronic device is connected between the second end of the second electrostatic protector and the first end of the third capacitor.

12. The electrostatic protection circuit according to claim 11, characterized in that: The power-consuming element also includes a power supply of the electronic device, a first end of the power supply is connected between the second end of the second electrostatic protector and the first end of the third capacitor, and the second end of the power supply is grounded; the first end of the first capacitor is connected to the first end of the power supply through at least one fifth diode.

13. The electrostatic protection circuit according to claim 12, characterized in that: A metal sheet is further provided between the second end of the third capacitor and the ground line.

14. The electrostatic protection circuit according to claim 4, characterized in that: The inductor includes a differential mode inductor or a common mode inductor.

15. The electrostatic protection circuit according to claim 1, characterized in that: The first capacitor includes at least two capacitors whose impedance characteristic curves are located at different resonance points, and the resonance point of each capacitor corresponds to a different interference frequency point of electrostatic discharge or air discharge.

16. An electronic device, characterized in that: It comprises a shielding shell, wherein a protected component is arranged inside the shielding shell, and an input / output interface is also arranged outside the shielding shell, wherein the input / output interface is connected to the protected component via a signal line, and the signal line is provided with an electrostatic protection circuit as described in any one of claims 1-15.

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