High-voltage electrostatic protection circuit, power chip and electrical equipment

Abstract

The application discloses a high-voltage electrostatic protection circuit, a power chip and an electrical equipment, wherein the high-voltage electrostatic protection circuit comprises: a trigger unit, a first end of the trigger unit being adapted to be connected to a power supply, a second end of the trigger unit being grounded, the trigger unit being configured to generate a trigger signal in the case that the voltage of the power supply reaches a first preset voltage and an electrostatic pulse exists; a discharge unit, a first end of the discharge unit being adapted to be connected to the power supply, a second end of the discharge unit being grounded; and a control unit, the control unit being configured to generate a control current according to the trigger signal, wherein the control current is used to control the discharge unit to be turned on to discharge the electrostatic pulse. The high-voltage electrostatic protection circuit, as long as the voltage of the power supply does not reach the first preset voltage, the control unit will not control the discharge unit to discharge even if the switching frequency of the power supply is high, thereby avoiding the occurrence of the mis-conduction of the discharge unit.

Description

Technical Field

[0001] This application relates to the field of electrostatic discharge protection technology, and in particular to a high-voltage electrostatic discharge protection circuit, a power chip, and electrical equipment. Background Technology

[0002] ESD (Electro-Static Discharge) surge protection is a significant challenge in high-voltage applications. Under high-voltage conditions, chips must possess excellent withstand capabilities for both high voltage and high current, requiring a very small chip area with high ESD robustness.

[0003] In current high-voltage BCD (Bipolar, CMOS, DMOS integration) processes, the uneven thickness of the gate oxide layer leads to varying conductivity, and the process breakdown junction voltage is much higher than the operating voltage. Conventional multi-gate silicon parallel connection protection methods are ineffective, while stacking low-voltage transistors results in wasted area. To address this process bottleneck, the industry has adopted various circuit-controlled protection structures, such as RC-HVMOS (capacitor, resistor, and high-voltage switching device) structures and cascaded PNPN structures. However, these structures pose certain risks when applied to power switching chips. Power switching frequencies are in the hundreds of kilohertz range. The frequency detection method of the RC-HVMOS structure can cause the electrostatic discharge tube to mis-turn on under normal operation, while the trigger voltage of the cascaded PNPN architecture is limited by its inelastic design window, affecting power startup. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the first objective of this invention is to provide a high-voltage electrostatic protection circuit. When the power supply voltage reaches a first preset voltage and an electrostatic pulse is present, the trigger unit generates a trigger signal. Even if the power switching frequency is high, as long as the power supply voltage does not reach the first preset voltage, the control unit will not control the discharge unit to discharge, thereby preventing the discharge unit from mis-energizing.

[0005] The second objective of this invention is to provide a power chip.

[0006] The third objective of this invention is to provide an electrical device.

[0007] To achieve the above objectives, a high-voltage electrostatic protection circuit is provided according to a first aspect embodiment of the present invention, comprising: a trigger unit, a first end of which is adapted to be connected to a power supply, a second end of which is grounded, the trigger unit being configured to generate a trigger signal when the voltage of the power supply reaches a first preset voltage and an electrostatic pulse is present; a discharge unit, a first end of which is adapted to be connected to a power supply, the second end of which is grounded; and a control unit, the control unit being configured to generate a control current according to the trigger signal, wherein the control current is used to control the discharge unit to conduct in order to discharge the electrostatic pulse.

[0008] According to an embodiment of the present invention, a high-voltage electrostatic protection circuit includes a trigger unit, a discharge unit, and a control unit. The first end of the trigger unit is adapted to be connected to a power supply, and the second end of the trigger unit is grounded. The trigger unit is configured to generate a trigger signal when the voltage of the power supply reaches a first preset voltage and an electrostatic pulse is present. Therefore, even if the power switching frequency is high, as long as the voltage of the power supply does not reach the first preset voltage, a trigger signal will not be generated, and the control unit will not control the discharge unit to discharge, thereby avoiding the situation where the discharge unit is mis-energized, and thus improving the robustness of the high-voltage electrostatic protection circuit.

[0009] According to one embodiment of the present invention, the triggering unit includes: a clamping module, the clamping module including a plurality of cascaded switching transistors, a first end of the clamping module adapted to be connected to a power supply, and a second end of the clamping module grounded; a pulse detection module, the first end of the pulse detection module adapted to be connected to a power supply, and the second end of the pulse detection module connected to the control terminal of at least one of the cascaded switching transistors, the pulse detection module being configured to control the middle switching transistor to conduct in the event of a detected electrostatic pulse, so that the clamping module outputs a trigger signal when the voltage of the power supply reaches a first preset voltage.

[0010] According to one embodiment of the present invention, when the middle switch is turned on, the remaining switch in the plurality of cascaded switch transistors is broken down when the voltage of the power supply reaches a first preset voltage.

[0011] According to one embodiment of the present invention, when the remaining switch in a plurality of cascaded switching transistors is broken down, the voltage across the clamping module is clamped to a second preset voltage, wherein the second preset voltage is less than the first preset voltage.

[0012] According to one embodiment of the present invention, the clamping module further includes at least two first resistors, the first resistors being disposed between the control terminal and the first terminal of the remaining switching transistors excluding the middle switching transistor.

[0013] According to one embodiment of the present invention, the pulse detection module includes: at least one second resistor and at least two cascaded switching transistors, the second resistor being disposed between the control terminals of the two switching transistors, the second terminal of the last of the at least two cascaded switching transistors being connected to the control terminal of the middle switching transistor, and the control terminal of the last switching transistor being connected to the second terminal of the middle switching transistor.

[0014] According to one embodiment of the present invention, when the electrostatic pulse is greater than a preset frequency, at least one second resistor and at least two cascaded switching transistors control the central switching transistor to turn on.

[0015] According to one embodiment of the present invention, the multiple switching transistors in the clamping module are low-voltage switching transistors.

[0016] According to one embodiment of the present invention, the control unit includes: a third resistor, one end of which is adapted to be connected to a power supply; a fourth resistor, the other end of which is connected to the other end of the third resistor; a first switching transistor, the first end of which is connected to the other end of the third resistor, the control terminal of which is connected to the other end of the fourth resistor, and the second end of which is grounded; a first Zener diode, the anode of which is connected to the other end of the fourth resistor and the control terminal of the first switching transistor; a second switching transistor, the first end of which is connected to the cathode of the first Zener diode, and the second end of which is grounded; a second Zener diode, the cathode of which is connected to a clamping module, and the anode of which is connected to the control terminal of the second switching transistor; and a fifth resistor, one end of which is connected to the anode of the second Zener diode and the control terminal of the second switching transistor, and the other end of which is grounded.

[0017] According to one embodiment of the present invention, the second Zener diode is broken down by a trigger signal so that the second switch and the first switch are turned on.

[0018] According to one embodiment of the present invention, the discharge unit includes: a third switch transistor, the first end of the third switch transistor being adapted to be connected to a power supply, the control terminal of the third switch transistor being connected to the first end of a second switch transistor, the second end of the third switch transistor being grounded, and the third switch transistor and the second switch transistor forming a Darlington structure.

[0019] According to one embodiment of the present invention, the first switch, the second switch, and the third switch are high-voltage switch transistors.

[0020] According to one embodiment of the present invention, the second switch and the third switch are of the same type.

[0021] According to one embodiment of the present invention, the first switch and the second switch are switch transistors of different types.

[0022] To achieve the above objectives, a power chip is provided according to a second aspect of the present invention, including the high voltage electrostatic protection circuit of any of the foregoing embodiments.

[0023] According to the power chip of the present invention, by employing the above-mentioned high-voltage electrostatic protection circuit, the triggering unit generates a trigger signal when the voltage of the power supply reaches the first preset voltage and an electrostatic pulse is present. Even if the power switching frequency is high, as long as the voltage of the power supply does not reach the first preset voltage, the control unit will not control the discharge unit to discharge, thereby avoiding the situation where the discharge unit is mis-energized.

[0024] To achieve the above objectives, an electrical device is provided according to a third aspect of the present invention, comprising the aforementioned power chip.

[0025] According to the electrical device of the present invention, by employing the power chip described above, the triggering unit generates a trigger signal when the voltage of the power supply reaches a first preset voltage and an electrostatic pulse is present. Even if the power switching frequency is high, as long as the voltage of the power supply does not reach the first preset voltage, the control unit will not control the discharge unit to discharge, thereby avoiding the situation where the discharge unit is mis-energized.

[0026] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0027] Figure 1 This is a system schematic diagram of a high-voltage electrostatic protection circuit according to an embodiment of the present invention;

[0028] Figure 2 This is a circuit diagram of a high-voltage electrostatic protection circuit according to an embodiment of the present invention;

[0029] Figure 3 This is a clamping timing diagram of a clamping module under 6.5kV equivalent electrostatic discharge according to an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram showing the connection between a first P-type switch and a second and a third N-type switch according to an embodiment of the present invention.

[0031] Figure 5 This is a schematic diagram showing the connection between the first and third switching transistors, which are P-type switching transistors, and the second switching transistor, which is N-type switching transistor, according to an embodiment of the present invention.

[0032] Figure 6 This is a schematic diagram showing the connection between the first and third switching transistors, which are N-type switching transistors, and the second switching transistor, which is a P-type switching transistor, according to an embodiment of the present invention.

[0033] Figure 7 This is a schematic diagram of the trigger channel of a high-voltage electrostatic protection circuit according to an embodiment of the present invention;

[0034] Figure 8 This is a system schematic diagram of a power chip according to an embodiment of the present invention;

[0035] Figure 9 This is a system schematic diagram of an electrical device according to an embodiment of the present invention. Detailed Implementation

[0036] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0037] The high-voltage electrostatic protection circuit, power chip, and electrical equipment of the present invention are described below with reference to the accompanying drawings.

[0038] Figure 1 This is a system schematic diagram of a high-voltage electrostatic protection circuit according to an embodiment of the present invention. Figure 1 As shown, the high-voltage electrostatic protection circuit includes: a trigger unit 10, a discharge unit 20, and a control unit 30.

[0039] The trigger unit 10 has a first end adapted to be connected to the power supply VDD, and a second end grounded. The trigger unit 10 is configured to generate a trigger signal when the voltage of the power supply VDD reaches a first preset voltage and an electrostatic pulse is present. The discharge unit 20 has a first end adapted to be connected to the power supply VDD, and a second end grounded. The control unit 30 is configured to generate a control current according to the trigger signal, wherein the control current is used to control the discharge unit 20 to conduct in order to discharge the electrostatic pulse.

[0040] Specifically, the trigger unit 10 is disposed between the power supply VDD and ground. When the voltage of the power supply VDD reaches a first preset voltage and an electrostatic pulse is present, the trigger unit 10 generates a trigger signal. The control unit 30 is disposed between the trigger unit 10 and the discharge unit 20. After the trigger unit 10 generates the trigger signal, the control unit 30 controls the discharge unit 20 to conduct according to the trigger signal to discharge the electrostatic pulse. If the voltage of the power supply VDD does not reach the first preset voltage, even if the switching frequency of the power supply VDD is relatively fast, the trigger unit 10 will not generate a trigger signal. Since the control unit 30 does not receive a trigger signal, it will not generate the control current used to control the conduction of the discharge unit 20. Therefore, the discharge unit 20 will not experience false triggering.

[0041] In the above embodiments, the triggering unit generates a trigger signal when the power supply voltage reaches the first preset voltage and there is an electrostatic pulse. Even if the power switching frequency is high, as long as the power supply voltage does not reach the first preset voltage, the control unit will not control the discharge unit to discharge, thereby avoiding the situation where the discharge unit is mis-activated, and thus improving the robustness of the high voltage electrostatic protection circuit.

[0042] In some embodiments, such as Figure 2 As shown, the trigger unit 10 includes a clamping module 11 and a pulse detection module 12. The clamping module 11 includes multiple cascaded switching transistors M1-M4. The first end of the clamping module 11 is adapted to be connected to the power supply VDD, and the second end of the clamping module 11 is grounded. The first end of the pulse detection module 12 is adapted to be connected to the power supply VDD, and the second end of the pulse detection module 12 is connected to the control terminal of at least one of the middle switching transistors M2 and M3 among the multiple cascaded switching transistors M1-M4. The pulse detection module 12 is configured to control the middle switching transistors M2 and M3 to conduct when an electrostatic pulse is detected, so that the clamping module 11 outputs a trigger signal when the voltage of the power supply VDD reaches a first preset voltage.

[0043] It should be noted that the number of switching transistors in the clamping module 11 needs to be determined based on the avalanche breakdown voltage of the switching transistors and the rated voltage of the switching transistors in the discharge unit 20. The first preset voltage is the sum of the avalanche breakdown voltages of the multiple switching transistors.

[0044] Specifically, the intermediate switching transistors M2 and M3 are the switching transistors in the clamping module 11 other than the switching transistor M1 connected to the power supply VDD and the grounded switching transistor M4. When there are multiple intermediate switching transistors M2 and M3, the pulse detection module 12 can be connected to one intermediate switching transistor M2 or multiple intermediate switching transistors M2 and M3. When the pulse detection module 12 detects an electrostatic pulse, it pulls down the gate potential, causing the intermediate switching transistor M2 to conduct. Thus, when the voltage of the power supply VDD reaches the first preset voltage, the clamping module 11 is in a closed circuit state, and the clamping module 11 can output a trigger signal. During normal high-voltage operation, there is no electrostatic pulse, and the pulse detection module 12 does not detect an electrostatic pulse, so it will not control the intermediate switching transistor M2 to conduct. Therefore, the clamping module 11 is in an open circuit state, and even when the voltage of the power supply VDD reaches the first preset voltage, the clamping module 11 will not output a trigger signal, so the discharge unit 20 will not discharge.

[0045] by Figure 2As shown in the example, the clamping module 11 has four cascaded switching transistors M1-M4. The pulse detection module 12 is connected to the switching transistor M2. When the pulse detection module 12 detects an electrostatic pulse, it controls the switching transistor M2 to turn on so that the clamping module 11 outputs a trigger signal when the voltage of the power supply VDD reaches the first preset voltage.

[0046] In the above embodiments, by controlling the number of switching transistors in the clamping module, the triggering unit can be applied to different high-voltage protections, thereby enhancing the application capability of the high-voltage electrostatic protection circuit.

[0047] In some embodiments, when the middle switch M2 is turned on, the remaining switches M1, M3, and M4 in the plurality of cascaded switches are broken down when the voltage of the power supply VDD reaches a first preset voltage.

[0048] Specifically, with Figure 2 Taking the example shown, if the avalanche breakdown voltage of the switching transistor is 12V, the first preset voltage is the sum of the avalanche breakdown voltages of the four switching transistors M1-M4, i.e., 48V. When switching transistor M2 is turned on, if the power supply VDD reaches 48V, switching transistor M1 is avalanche broken down, and switching transistor M1 turns on, generating a breakdown current. This breakdown current flows through switching transistor M2 and then into switching transistor M3. Then, switching transistor M3 is avalanche broken down, and switching transistor M3 turns on, generating a breakdown current. Part of this breakdown current flows to switching transistor M4, and the remaining breakdown current (i.e., the trigger signal) flows to control unit 30. Switch transistor M4 is avalanche broken down, and switching transistor M4 turns on, with the breakdown current generated by M4 flowing to ground. Therefore, when the middle switching transistor M2 is turned on, if the power supply VDD reaches the first preset voltage, the remaining switching transistors M1, M3, and M4 are all avalanche broken down, and then the remaining switching transistors M1, M3, and M4 turn on, generating a trigger signal.

[0049] In some embodiments, when the remaining switching transistors M1, M3, and M4 in a plurality of cascaded switching transistors are broken down, the voltage across the clamping module 11 is clamped to a second preset voltage, wherein the second preset voltage is less than the first preset voltage.

[0050] Specifically, when a switching transistor is avalanche-damped, the voltage across the transistor is clamped to the avalanche breakdown voltage. When the remaining switching transistors M1, M3, and M4 are avalanche-damped, the voltage across the clamping module 11 is clamped to a second preset voltage, which is the sum of the avalanche breakdown voltages of the remaining switching transistors M1, M3, and M4. Since the first preset voltage is the sum of the avalanche breakdown voltages of multiple switching transistors M1-M4, and the second preset voltage is the sum of the avalanche breakdown voltages of the remaining switching transistors M1, M3, and M4, the second preset voltage is less than the first preset voltage.

[0051] For example, such as Figure 3The simulation shows that when a 6.5kV equivalent electrostatic pulse is applied to the high-voltage electrostatic protection circuit, the switch M2 in the clamping module 11 is turned on, and the remaining switches M1, M3, and M4 are avalanche breakdowned, clamping the voltage across the clamping module 11 to approximately 35V. If the switches in the control unit 30 and the discharge unit 20 are 40V high-voltage switches, the clamping module 11 can clamp the voltage to 35V, meeting the safety standards of the switches in the control unit 30 and the discharge unit 20.

[0052] In the above embodiment, when the remaining switching transistor is broken down, the voltage across the clamping module is clamped to the second preset voltage, which reduces the voltage across the clamping module, thereby reducing the start voltage node of the high voltage electrostatic protection and thus avoiding the accumulation of high heat energy.

[0053] In some embodiments, such as Figure 2 As shown, the clamping module 11 also includes at least two first resistors R1, which are disposed between the control terminals and the first terminals of the remaining switching transistors M1, M3, and M4 (excluding the middle switching transistor).

[0054] Specifically, the first resistor R1 is a pull-up resistor for the control terminals of the remaining switching transistors M1, M3, and M4, which pulls the control terminals of the remaining switching transistors M1, M3, and M4 to a high potential to prevent the remaining switching transistors from being turned on by controlling the gate.

[0055] by Figure 2 Taking the example shown, there are three first resistors R1. The control terminal and the first terminal of switch M1 are connected to the first resistor R1. The control terminal of switch M2 is connected to the pulse detection module 12. The control terminal and the first terminal of switch M3 are connected to the first resistor R1. The control terminal and the first terminal of switch M4 are also connected to the first resistor R1. Therefore, the control terminals of switches M1, M3, and M4 are all pulled to a high potential by the first resistor R1. Thus, the control terminals of switches M1, M3, and M4 cannot be turned on through the control gate; they can only be turned on by high-voltage avalanche breakdown.

[0056] In some embodiments, the pulse detection module 12 includes: at least one second resistor R2 and at least two cascaded switching transistors M5-M8. The second resistor R2 is disposed between the control terminals of the two switching transistors. The second terminal of the last switching transistor M8 in the at least two cascaded switching transistors M5-M8 is connected to the control terminal of the middle switching transistor M2. The control terminal M8 of the last switching transistor is connected to the second terminal of the middle switching transistor M2.

[0057] Specifically, when the voltage of the power supply VDD reaches the first preset voltage, the switching transistors M5-M8 can be equivalent to resistors, pulling up the potential of the control terminal of the middle switching transistor M2 to withstand the high-voltage environment. When an electrostatic pulse is detected, the switching transistors can be equivalent to capacitors.

[0058] In an optional embodiment, the pulse detection module 12 further includes a sixth resistor R6, which is disposed between the first terminal of the first switching transistor M5 and the power supply VDD to protect the switching transistor from being damaged by high voltage.

[0059] In the above embodiments, when the power supply voltage is over-voltage, the switching transistor can be equivalent to a resistor. The gate of the middle switching transistor is connected to the power supply through a resistor, so that the middle switching transistor can withstand the high voltage environment, thereby further improving the robustness of the high voltage electrostatic protection circuit.

[0060] Furthermore, in some embodiments, when the electrostatic pulse is greater than a preset frequency, at least one second resistor R2 and at least two cascaded switching transistors M5-M8 control the central switching transistor M2 to conduct.

[0061] Specifically, the preset frequency is calculated using the following formula:

[0062] fc = 1 / 2πRC

[0063] Where fc is the preset frequency, R is the resistance value of at least one second resistor R2, and C is the capacitance value of at least two cascaded switching transistors M5-M8.

[0064] The preset frequency is typically within 10 times the pulse width of the electrostatic pulse. The number of the second resistor R2 and the number of switching transistors can be determined based on the preset frequency. When the electrostatic pulse frequency of the power supply is greater than the preset frequency, at least one second resistor R2 and at least two cascaded switching transistors M5-M8 control the central switching transistor M2 to conduct; when the electrostatic pulse frequency of the power supply is less than or equal to the preset frequency, at least one second resistor R2 and at least two cascaded switching transistors M5-M8 control the central switching transistor M2 to turn off.

[0065] It should be noted that in practical applications, the pulse detection module 12 is not limited to a circuit composed of resistors and switching transistors. Any circuit that can generate a preset frequency can be used as the pulse detection module 12. For example, a circuit composed of resistors and capacitors, or a circuit composed of any expandable resistive devices and any expandable capacitive devices. Expandable resistive devices include, but are not limited to, polysilicon resistors, field-effect transistor resistors, trap resistors, and diffuse resistors. Expandable capacitive devices include, but are not limited to, field-effect transistor capacitors, diode capacitors, MOM (Metal-Oxide-Metal) capacitors, and MIM (Metal-Insulator-Metal) capacitors. No specific restrictions are imposed here.

[0066] In some embodiments, the multiple switching transistors in the clamping module 11 are low-voltage switching transistors.

[0067] It is understandable that the switching transistors in the trigger unit 10 are all low-voltage switching transistors. Low-voltage switching transistors can improve electrostatic sensitivity, thereby further improving the robustness of the high-voltage electrostatic protection circuit. Furthermore, the low-voltage switching transistors are only used in the trigger unit 10 and are not used in the electrostatic protection device. Therefore, the low-voltage switching transistors in the trigger unit 10 can be selected with a smaller area, thereby reducing the area of ​​the high-voltage electrostatic protection circuit.

[0068] In one alternative implementation, the plurality of switching transistors in the clamping module 11 are P-type low-voltage switching transistors.

[0069] It should be noted that, Figure 2 The switching transistors of the trigger unit 10 are all P-type low-voltage switching transistors. If N-type low-voltage switching transistors are used, the connection method of the switching transistors is different. The substrate of the switching transistor needs to be connected to the second end of the switching transistor. The control terminal of the switching transistor of the clamping module 11 needs to be pulled low through the first resistor R1.

[0070] In some embodiments, such as Figure 2 As shown, the control unit 30 includes: a third resistor R3, a fourth resistor R4, a first switching transistor M10, a first Zener diode D1, a second switching transistor M9, a second Zener diode D2, and a fifth resistor R5. One end of the third resistor R3 is adapted to be connected to the power supply VDD; the other end of the fourth resistor R4 is connected to the other end of the third resistor R3; the first end of the first switching transistor M10 is connected to the other end of the third resistor R3, the control terminal of the first switching transistor M10 is connected to the other end of the fourth resistor R4, and the second end of the first switching transistor M10 is grounded; the anode of the first Zener diode D1 is connected to the other end of the fourth resistor R4 and the control terminal of the first switching transistor M10, respectively; the first end of the second switching transistor M9 is connected to the cathode of the first Zener diode D1, and the second end of the second switching transistor M9 is grounded; the cathode of the second Zener diode D2 is connected to the clamping module 11, and the anode of the second Zener diode D2 is connected to the control terminal of the second switching transistor M9; one end of the fifth resistor R5 is connected to the anode of the second Zener diode D2 and the control terminal of the second switching transistor M9, respectively, and the other end of the fifth resistor R5 is grounded.

[0071] Specifically, during normal high-voltage operation, the control terminal of the first switching transistor M10 is connected to the power supply VDD through the third resistor R3 and the fourth resistor R4, and the control terminal of the switching transistor is grounded through the fifth resistor R5. The potential of the control terminal of the first switching transistor M10 is pulled high, and the potential of the control terminal of the second switching transistor M9 is pulled low. Therefore, both the first switching transistor M10 and the second switching transistor M9 are in the off state. Simultaneously, the pulse detection module 12 does not detect an electrostatic pulse and will not control the switching transistor M2 to conduct. Therefore, the clamping module 11 will not conduct and will not generate a trigger signal. The first switching transistor M10 and the second switching transistor M9 will not conduct, and the discharge unit 20 will not discharge. The first voltage regulator is positioned between the first terminal and the control terminal of the first switching transistor M10, serving a safety protection function to prevent overvoltage from breaking down the insulation layer between the first terminal and the control terminal of the first switching transistor M10. When an electrostatic pulse is present, if the voltage of the power supply VDD reaches the first preset voltage, the trigger unit 10 generates a trigger signal, and the first switch M10 and the second switch M9 of the control unit 30 are turned on to generate a control current so that the discharge unit 20 discharges the electrostatic pulse.

[0072] Furthermore, since the clamping module 11 can clamp the voltage across its two ends to a second preset voltage, the voltage across the first switch M10 and the second switch M9 is relatively small.

[0073] In one optional embodiment, the control unit 30 further includes a third Zener diode D3 and a fourth Zener diode D4. The cathode of the third Zener diode D3 is adapted to be connected to the power supply VDD, the anode of the third Zener diode D3 is connected to the other end of the third resistor R3, the cathode of the fourth Zener diode D4 is connected to the other end of the third resistor R3, and the anode of the fourth Zener diode D4 is connected to the control terminal of the second switch M9 to prevent the second switch M9 from being broken down and to improve the robustness of the second switch M9.

[0074] In the above embodiments, the first and second switching transistors are only used to generate control current and are not used to discharge electrostatic pulses. Furthermore, the voltage that the first and second switching transistors withstand is relatively small, so the first and second switching transistors can be small in size, such as 20µm in width, thereby further reducing the area of ​​the high-voltage electrostatic protection circuit. In addition, the first Zener diode is placed between the first end and the control end of the first switching transistor, which can prevent overvoltage from breaking down the insulation layer between the first end and the control end of the first switching transistor, thereby improving the robustness of the first switching transistor.

[0075] In some embodiments, the second Zener diode D2 is triggered by a signal to break down, thereby turning on the second switch M9 and the first switch M10.

[0076] Specifically, after the trigger unit 10 generates a trigger signal, the second Zener diode D2 is reverse-broken down by the trigger signal, and the second Zener diode D2 generates a large breakdown current. The breakdown current causes the first switch M10 to turn on, and the first switch M10 turns on, which in turn causes the second switch M9 to turn on, thereby generating a control current.

[0077] In the above embodiment, after the first switch is turned on, a positive feedback PNPN channel of the parasitic NPN and PNP transistors of the SCR (Silicon Controlled Rectifier) ​​is triggered, which accelerates the turn-on of the second switch. This allows the control current to be generated more quickly, further accelerating the turn-on of the discharge unit. Therefore, the high-voltage electrostatic protection circuit can respond quickly under electrostatic pulse and discharge the electrostatic pulse.

[0078] In some embodiments, the discharge unit 20 includes: a third switch M11, the first end of the third switch M11 being adapted to be connected to the power supply VDD, the control terminal of the third switch M11 being connected to the first end of the second switch M9, the second end of the third switch M11 being grounded, and the third switch M11 and the second switch M9 forming a Darlington structure.

[0079] Specifically, during normal high-voltage operation, the control terminal of the third switch M11 is connected to the power supply VDD through the third resistor R3. The potential of the control terminal of the third switch M11 is pulled high, and the third switch M11 is in the off state. Because the first switch M10 and the second switch M9 are both in the off state, no control current is generated, so the third switch M11 will not conduct to discharge current. During electrostatic pulse (ESP) operation, the first switch M10 and the second switch M9 conduct, and the third switch M11 conducts. The third switch M11 and the second switch M9 form a Darlington structure. The third switch M11 and the second switch M9 can be equivalent to a switch with a large gate resistance. Increasing the gate resistance provides a good high-current path. The discharge time of the ESP is positively correlated with the gate resistance; the larger the gate resistance, the shorter the ESP discharge time.

[0080] In the above embodiment, the third switch and the second switch form a Darlington structure, which increases the gate resistance, improves the uniform conduction of the high voltage path during the electrostatic transient, and obtains a good high current channel, thereby accelerating the discharge of electrostatic pulses. Compared with single-switch gate oxide triggering, it improves the uniform conduction of the high voltage path during the electrostatic transient.

[0081] In some embodiments, the first switch M10, the second switch M9, and the third switch M11 are high-voltage switch transistors.

[0082] It is understandable that the first switch M10, the second switch M9, and the third switch M11 are used to discharge electrostatic pulses. Therefore, the use of high-voltage switches M10, M9, and M11 can effectively avoid the limitations of low-voltage switches in terms of electrostatic withstand capability. At the same time, due to the clamping effect of the clamping module 11, the voltage borne by the first switch M10, M9, and M11 is reduced. Therefore, the first switch M10, M9, and M11 can be selected as smaller high-voltage switches, thereby further reducing the area of ​​the high-voltage electrostatic protection circuit.

[0083] In one optional embodiment, the size of the third switch M11 is larger than that of the first switch M10 and the second switch M9, because the third switch M11 is a discharge tube for electrostatic pulses, and the electrostatic pulses that the third switch M11 withstands are relatively large, so the size of the third switch M11 is larger than that of the first switch M10 and the second switch M9.

[0084] In some embodiments, the second switch M9 and the third switch M11 are the same type of switch.

[0085] In other words, the first switch M10 and the second switch M9 are N-type or P-type switches, and the second switch M9 and the third switch M11 can be equivalent to switches of the same type.

[0086] Furthermore, in some embodiments, the first switch M10 and the second switch M9 are different types of switches.

[0087] It is understandable that when the second switch M9 and the third switch M11 are N-type switches, the first switch M10 is a P-type switch, and when the second switch M9 and the third switch M11 are P-type switches, the first switch M10 is an N-type switch.

[0088] by Figure 2 Taking the example shown, the second switch M9 and the third switch M11 are P-type switches, and the first switch M10 is an N-type switch. After the second Zener diode D2 breaks down, it generates a large current, which pulls up the gate potential of the first switch M10, turning on the first switch M10. After the first switch M10 turns on, it pulls down the gate potential of the second switch M9, turning on the second switch M9. After the second switch M9 turns on, it pulls down the gate potential of the third switch M11, turning on the third switch M11, thus discharging the electrostatic pulse.

[0089] When the second switch M9 and the third switch M11 are N-type switches, and the first switch M10 is a P-type switch, the connection method of the first switch M10, the second switch M9, and the third switch M11 is as follows: Figure 4 As shown.

[0090] In practical applications, the second switch M9 and the third switch M11 can also be different types of switches. The type of the first switch M10 needs to be determined according to the type of the second switch M9 to ensure that the second switch M9 can be triggered to turn on after the first switch M10 is turned on.

[0091] like Figure 5 As shown, when the second switch M9 is an N-type switch and the third switch M11 is a P-type switch, the first switch M10 is a P-type switch. Figure 6 As shown, when the second switch M9 is a P-type switch and the third switch M11 is an N-type switch, the first switch M10 is an N-type switch.

[0092] The technical solution of this application will be further described in detail below with reference to specific implementation methods:

[0093] like Figure 2 As shown, the high-voltage electrostatic protection circuit includes a trigger unit 10, a control unit 30, and a discharge unit 20.

[0094] The triggering unit 10 includes a clamping module 11 and a pulse detection module 12. The clamping module 11 includes four cascaded P-type low-voltage switching transistors M1-M4. The first end of the switching transistor M1 is adapted to be connected to the power supply VDD. A first resistor R1 is provided between the control terminal and the first end of the switching transistor M1. The first end of the switching transistor M2 is connected to the second end of the switching transistor M1. The control terminal of the switching transistor M2 is connected to the pulse detection module 12. The first end of the switching transistor M3 is connected to the second end of the switching transistor M2. A first resistor R1 is provided between the control terminal and the first end of the switching transistor M3. The first end of the switching transistor M4 is connected to the second end of the switching transistor M3. A first resistor R1 is provided between the control terminal and the first end of the switching transistor M4. The second end of the switching transistor M4 is grounded. The pulse detection module 12 includes three second resistors R2, a sixth resistor R6, and four cascaded P-type low-voltage switching transistors M5-M8. One end of the sixth resistor R6 is adapted to connect to the power supply VDD, and the other end of the sixth resistor R6 is connected to the first end of the switching transistor M5. The first end of the switching transistor M6 is connected to the second end of the switching transistor M5. The sixth resistor R6 is positioned between the control terminals of the switching transistors M5 and M6. The first end of the switching transistor M7 is connected to the second end of the switching transistor M6. The sixth resistor R6 is positioned between the control terminals of the switching transistors M6 and M7. The first end of the switching transistor M8 is connected to the second end of the switching transistor M7. The sixth resistor R6 is positioned between the control terminals of the switching transistors M7 and M8. The second end of the switching transistor M8 is connected to the control terminal of the switching transistor M2. The control terminal of the switching transistor M8 is connected to the second end of the switching transistor M2.

[0095] The control unit 30 includes a third resistor R3, a fourth resistor R4, a first switching transistor M10, a first Zener diode D1, a second switching transistor M9, a second Zener diode D2, a fifth resistor R5, a third Zener diode D3, and a fourth Zener diode D4. The first switching transistor M10 is a P-type high-voltage switching transistor, and the second switching transistor M9 is an N-type high-voltage switching transistor. One end of the third resistor R3 is adapted to be connected to the power supply VDD. The other end of the fourth resistor R4 is connected to the other end of the third resistor R3. The first end of the first switching transistor M10 is connected to the other end of the third resistor R3. The control terminal of the first switching transistor M10 is connected to the other end of the fourth resistor R4. The second end of the first switching transistor M10 is grounded. The anode of the first Zener diode D1 is connected to the other end of the fourth resistor R4 and the fourth Zener diode D4. The control terminal of the first switching transistor M10 is connected. The first terminal of the second switching transistor M9 is connected to the cathode of the first Zener diode D1, and the second terminal of the second switching transistor M9 is grounded. The cathode of the second Zener diode D2 is connected to the clamping module 11, and the anode of the second Zener diode D2 is connected to the control terminal of the second switching transistor M9. One end of the fifth resistor R5 is connected to the anode of the second Zener diode D2 and the control terminal of the second switching transistor M9, and the other end of the fifth resistor R5 is grounded. The cathode of the third Zener diode D3 is adapted to be connected to the power supply VDD, and the anode of the third Zener diode D3 is connected to the other end of the third resistor R3. The cathode of the fourth Zener diode D4 is connected to the other end of the third resistor R3, and the anode of the fourth Zener diode D4 is connected to the control terminal of the second switching transistor M9.

[0096] The discharge unit 20 includes a third switch transistor M11, which is a P-type high-voltage switch transistor. The first end of the third switch transistor M11 is adapted to be connected to the power supply VDD. The control end of the third switch transistor M11 is connected to the first end of the second switch transistor M9. The second end of the third switch transistor M11 is grounded. The third switch transistor M11 and the second switch transistor M9 form a Darlington structure.

[0097] During normal high-voltage operation, the control terminal of the first switch M10 is grounded through the fifth resistor R5, and the control terminal of the second switch M10 is connected to the power supply VDD through the third resistor R3 and the fourth resistor R4. The potential of the control terminal of the first switch M10 is pulled low, the potential of the control terminal of the second switch M9 is pulled high, and the control terminal of the third switch M11 is connected to the power supply VDD through the third resistor R3. Therefore, the potential of the control terminal of the third switch M11 is pulled high. Simultaneously, because the trigger unit 10 does not detect an electrostatic pulse, it cannot generate a trigger signal. Therefore, the first switch M10 and the second switch M9 cannot conduct, and the third switch M11 cannot conduct to release the electrostatic pulse.

[0098] When an electrostatic pulse is present, if the voltage of the power supply VDD does not reach the first preset voltage, even if the switch M2 is turned on, the switches M1, M3 and M4 cannot be broken down. Therefore, the trigger unit 10 cannot generate a trigger signal, the first switch M10 and the second switch M9 cannot be turned on, and the third switch M11 cannot be turned on to release the electrostatic pulse.

[0099] When an electrostatic pulse is present and the voltage of the power supply VDD reaches a first preset voltage, the pulse detection module 12 controls the switch M2 to turn on. Switches M1, M3, and M4, after being avalanche breakdown, turn on, generating a trigger signal. This trigger signal reverse-biased breakdown of the second Zener diode D2, which generates a trigger signal Trigger1 to pull up the control terminal potential of the first switch M10, causing it to turn on and generate the signal... Figure 7 In the positive feedback PNPN channel shown, when the DNW well is pulled low, the first switch M10 is turned on, and its first terminal is at a low potential, thereby generating a trigger signal Trigger2. Then, the control terminal potential of the second switch M9 is pulled low by the trigger signal Trigger2, and the second switch M9 is turned on. After the second switch M9 is turned on, its first terminal is at a low potential, thereby generating a trigger signal Trigger3. Then, the control terminal of the third switch M11 is pulled low by the trigger signal Trigger3, and the third switch M11 is turned on, thus discharging the electrostatic pulse.

[0100] In the above embodiments, even if the power switching frequency is high, as long as the power supply voltage does not reach the first preset voltage, no trigger signal will be generated, and the control unit will not control the discharge unit to discharge, thereby avoiding the situation where the discharge unit is mis-activated; in addition, the third switch and the second switch form a Darlington structure, which increases the gate resistance and accelerates the discharge of electrostatic pulses, thereby improving the robustness of the high voltage electrostatic protection circuit.

[0101] In summary, the high-voltage electrostatic protection circuit according to embodiments of the present invention includes a trigger unit, a discharge unit, and a control unit. The first terminal of the trigger unit is adapted to be connected to a power supply, and the second terminal of the trigger unit is grounded. The trigger unit is configured to generate a trigger signal when the power supply voltage reaches a first preset voltage and an electrostatic pulse is present. Therefore, even if the power supply switching frequency is high, as long as the power supply voltage does not reach the first preset voltage, no trigger signal will be generated, and the control unit will not control the discharge unit to discharge, thereby avoiding the discharge unit from mis-energizing and improving the robustness of the high-voltage electrostatic protection circuit. Furthermore, the switching transistors, the first switching transistor, the second switching transistor, and the third switching transistor can be selected from smaller transistors, thereby reducing the area of ​​the high-voltage electrostatic protection circuit. Further, the third switching transistor and the second switching transistor constitute a Darlington structure, which increases the gate resistance and accelerates the discharge of the electrostatic pulse, thereby further improving the robustness of the high-voltage electrostatic protection circuit.

[0102] Corresponding to the above embodiments, embodiments of the present invention also provide a power chip. For example... Figure 8 As shown, the power chip 200 includes the high voltage electrostatic protection circuit 100 of any of the aforementioned embodiments.

[0103] According to the power chip of the present invention, by employing the above-mentioned high-voltage electrostatic protection circuit, the triggering unit generates a trigger signal when the voltage of the power supply reaches the first preset voltage and an electrostatic pulse is present. Even if the power switching frequency is high, as long as the voltage of the power supply does not reach the first preset voltage, the control unit will not control the discharge unit to discharge, thereby avoiding the situation where the discharge unit is mis-energized.

[0104] Corresponding to the above embodiments, embodiments of the present invention also provide an electrical device. For example... Figure 9 As shown, electrical equipment 300 includes the aforementioned power chip 200.

[0105] It should be noted that electrical equipment includes, but is not limited to, household appliances, office automation equipment, audio equipment, video equipment, and industrial equipment; no specific restrictions are imposed here.

[0106] According to the electrical device of the present invention, by employing the power chip described above, the triggering unit generates a trigger signal when the voltage of the power supply reaches a first preset voltage and an electrostatic pulse is present. Even if the power switching frequency is high, as long as the voltage of the power supply does not reach the first preset voltage, the control unit will not control the discharge unit to discharge, thereby avoiding the situation where the discharge unit is mis-energized.

[0107] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0108] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0109] Furthermore, the terms "first," "second," etc., used in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance, or implicitly specifying the number of technical features indicated in this embodiment. Therefore, features defined with terms such as "first" and "second" in the embodiments of this invention can explicitly or implicitly indicate that the embodiment includes at least one of those features. In the description of this invention, the word "multiple" means at least two or more, such as two, three, four, etc., unless otherwise explicitly specified in the embodiments.

[0110] In this invention, unless otherwise explicitly specified or limited in the embodiments, the terms "installation," "connection," "joining," and "fixing" appearing in the embodiments should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral part; it can also be a mechanical connection, an electrical connection, etc. Of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components, or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific implementation.

[0111] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0112] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A high voltage electrostatic protection circuit, characterized by, include: A trigger unit, wherein a first end of the trigger unit is adapted to be connected to a power supply, a second end of the trigger unit is grounded, and the trigger unit is configured to generate a trigger signal when the voltage of the power supply reaches a first preset voltage and an electrostatic pulse is present; A discharge unit, wherein a first end of the discharge unit is adapted to be connected to the power supply, and a second end of the discharge unit is grounded; A control unit configured to generate a control current based on the trigger signal, wherein the control current is used to control the discharge unit to conduct in order to discharge the electrostatic pulse; The triggering unit includes: A clamping module, comprising multiple cascaded switching transistors, wherein a first terminal of the clamping module is adapted to be connected to the power supply, and a second terminal of the clamping module is grounded; A pulse detection module, wherein a first end of the pulse detection module is adapted to be connected to the power supply, and a second end of the pulse detection module is connected to the control terminal of at least one of the cascaded switching transistors, and the pulse detection module is configured to control the middle switching transistor to conduct when the electrostatic pulse is detected, so that the clamping module outputs the trigger signal when the voltage of the power supply reaches the first preset voltage; When the central switch is turned on, the remaining switches in the plurality of cascaded switches are broken down when the voltage of the power supply reaches the first preset voltage.

2. The high-voltage electrostatic protection circuit according to claim 1, characterized in that, When the remaining switch in the plurality of cascaded switching transistors is broken down, the voltage across the clamping module is clamped to a second preset voltage, wherein the second preset voltage is less than the first preset voltage.

3. The high-voltage electrostatic protection circuit according to claim 1, characterized in that, The clamping module further includes at least two first resistors, which are disposed between the control terminal and the first terminal of the remaining switching transistors other than the central switching transistor.

4. The high-voltage electrostatic protection circuit according to claim 1, characterized in that, The pulse detection module includes: at least one second resistor and at least two cascaded switching transistors. The second resistor is disposed between the control terminals of the two switching transistors. The second terminal of the last of the at least two cascaded switching transistors is connected to the control terminal of the middle switching transistor, and the control terminal of the last switching transistor is connected to the second terminal of the middle switching transistor.

5. The high-voltage electrostatic protection circuit according to claim 4, characterized in that, When the frequency of the power supply is greater than a preset frequency, the at least one second resistor and the at least two cascaded switching transistors control the middle switching transistor to turn on.

6. The high-voltage electrostatic protection circuit according to any one of claims 2-5, characterized in that, The clamping module contains multiple low-voltage switching transistors.

7. The high-voltage electrostatic protection circuit according to claim 6, characterized in that, The control unit includes: A third resistor, one end of which is adapted to be connected to the power supply; A fourth resistor, one end of which is connected to the other end of the third resistor; The first switch transistor has a first terminal connected to the other terminal of the third resistor, a control terminal connected to the other terminal of the fourth resistor, and a second terminal grounded. The first Zener diode, the anode of the first Zener diode is connected to the other end of the fourth resistor and the control terminal of the first switching transistor respectively; The second switching transistor has its first terminal connected to the cathode of the first Zener diode and its second terminal grounded. The second Zener diode has its cathode connected to the clamping module and its anode connected to the control terminal of the second switching transistor. The fifth resistor has one end connected to the anode of the second Zener diode and the control terminal of the second switching transistor, and the other end grounded.

8. The high-voltage electrostatic protection circuit according to claim 7, characterized in that, The second Zener diode is broken down by the trigger signal, so that the second switch and the first switch are turned on.

9. The high-voltage electrostatic protection circuit according to claim 7, characterized in that, The discharge unit includes: a third switch transistor, the first end of which is adapted to be connected to the power supply, the control end of which is connected to the first end of the second switch transistor, the second end of which is grounded, and the third switch transistor and the second switch transistor form a Darlington structure.

10. The high-voltage electrostatic protection circuit according to claim 9, characterized in that, The first switch, the second switch, and the third switch are high-voltage switch transistors.

11. The high-voltage electrostatic protection circuit according to claim 9, characterized in that, The second and third switching transistors are of the same type.

12. The high-voltage electrostatic protection circuit according to claim 11, characterized in that, The first switch and the second switch are different types of switch.

13. A power chip, characterized in that, Includes a high-voltage electrostatic protection circuit according to any one of claims 1-12.

14. An electrical appliance, characterized in that, Includes the power chip according to claim 13.

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