Multifunctional rapid protection circuit

Abstract

The invention discloses a multifunctional rapid protection circuit, and relates to the field of circuit protection, the multifunctional rapid protection circuit comprises a switch tube Q1 and a switch tube Q2, and the first end of the switch tube Q1 is connected with the first end of a resistor R1, an input interface positive electrode P1 and the first end of a resistor R2. After conduction, the voltage drop is extremely small, so that the loss is extremely small, the heating is little, cooling fins are not needed, and the cost is reduced; multiple protection circuits are arranged, few devices are occupied, and the cost is saved; a plurality of protection circuits such as an undervoltage protection circuit, a common-mode low-frequency and high-frequency anti-interference circuit, an anti-reverse-connection and anti-backward-flow protection circuit, an overvoltage detection protection circuit, an MCU enable circuit, a temperature protection control circuit, an anti-static protection circuit, an output overcurrent and short-circuit protection circuit and the like are arranged, so that the operation safety is protected, and part of the protection circuits can be removed according to actual conditions; and the applicability is high.

Description

Technical Field

[0001] The invention relates to the field of circuit protection, in particular to a multifunctional fast protection circuit. Background Art

[0002] In the electronics industry, many electronic products have various power supply circuits inside. According to the different functional requirements of the circuit, the appropriate topology architecture is selected to realize the power supply parameters. Based on the semiconductor integrated circuit, considering the packaging technology, the material's tolerance to high temperature, the layout space of the chip layout, the problem of high power consumption and heat generation, the general selection problem, the price cost problem, and the problem of product size limitation, the semiconductor IC manufacturer will make a compromise and no longer consider various protection circuits. However, in the actual design, it is necessary to consider the use conditions of electronic products under various working conditions, meet the requirements of various tests, safety certification requirements, meet industry product standards, and protect against user error operations and safety precautions, etc. The circuit design user must do secondary development to meet the design requirements, such as adding undervoltage protection circuits, common mode low frequency, high frequency anti-interference circuits, anti-reverse connection, anti-backflow protection circuits, overvoltage detection protection circuits, MCU enable circuits, temperature protection control circuits, anti-static protection circuits, output overcurrent, short circuit protection circuits, etc.

[0003] See also Figure 1 , which is a commonly used interface input and output control circuit in the existing market. It is relatively simple, with only one switch tube Q1, and Q2 is a crystal triode that enables the output control. The combination controls the output and non-output of P2. However, this circuit does not have any protection circuit, and the input and output are exposed. There is no protection mechanism circuit at all, which is very easy to damage, resulting in multiple repairs. Because Q1 is an NPN triode, the output P2 voltage depends on the voltage difference between the BE pins of the Q1 triode, which is generally 0.6-0.8V. Assuming the output current is 2A, the power consumption of Q1 P=2A*0.7V=1.4W, which is quite large. The triode with a small SMD package such as SOT-23 cannot be used. Therefore, when the output current is increased, Q1 heats up seriously, which has great application limitations of the circuit and can only be used in very small current power supply circuits. The general solution to this limitation is to enlarge the heat sink and attach it to the Q1 body, fix it with screws, and choose a Q1 transistor with a larger current model and larger package size (such as: TO-220, TO-3, TO-252, TO-263). This is costly and wastes a lot of PCB substrate space.

[0004] See also Figure 2 In addition, the market also uses multiple transistors to combine circuits to make circuit solutions with a few protection circuits (relatively simple), as shown below Figure 2. The circuit construction is very complicated, using 15 transistors and voltage-stabilizing diodes, and other resistor parts. The implementation cost is very high, the PCB space is large, and the protection circuit can only be designed in a targeted manner, that is, the protection circuit is very incomplete. There is a large loss between the input and output, and the heat caused by the large voltage difference is serious. Some merchants even make integrated circuits, with a long purchase cycle and ordering time, high cost, and only a few fixed models to choose from. Due to the limitations of use, fewer and fewer foreign early semiconductor manufacturers continue to produce, and do not do market maintenance and upgrades.

[0005] In summary, in order to reduce costs, the interface input and output control circuits on the market do not have or have a small number of related protection circuits, but there is still a problem of high cost, which needs to be improved. Summary of the invention

[0006] The object of the present invention is to provide a multifunctional fast protection circuit to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: A multifunctional fast protection circuit comprises a switch tube Q1 and a switch tube Q2, wherein a first end of the switch tube Q1 is connected to a first end of a resistor R1, a positive electrode P1 of an input interface, and a first end of the resistor R2, a second end of the switch tube Q1 is connected to a first end of a resistor R3, a second end of a capacitor C1, and a positive electrode P2 of an output interface, a second end of the resistor R3 is grounded, a first end of the capacitor C1 is grounded, a third end of the switch tube Q1 is connected to a first end of a resistor R4 and a second end of the resistor R1, a second end of the resistor R4 is connected to a first end of the switch tube Q2, a second end of the switch tube Q2 is grounded via a resistor R7, a third end of the switch tube Q2 is connected to a positive electrode of a diode ZD1, a negative electrode of the diode ZD1 is connected to a second end of the resistor R2 and a first end of a resistor R6, a second end of the resistor R6 is grounded, and both a negative electrode P4 of the input interface and a negative electrode P3 of the output interface are grounded.

[0008] As a further solution of the present invention: the multifunctional fast protection circuit also includes a common-mode low-frequency and high-frequency anti-interference circuit, and a common-mode low-frequency and high-frequency anti-interference circuit is added between the second end of the switch tube Q1 and the positive pole P2 of the output interface. The common-mode low-frequency and high-frequency anti-interference circuit includes a common-mode inductor LF1, a capacitor C2, a ferrite bead L1, and a ferrite bead L2. The first end of the common-mode inductor LF1 is connected to the second end of the switch tube Q1, the second end of the common-mode inductor LF1 is grounded, the third end of the common-mode inductor LF1 is connected to the first end of the ferrite bead L1 and the second end of the capacitor C2, the second end of the ferrite bead L1 is connected to the positive pole P2 of the output interface, the first end of the capacitor C2 is grounded, and the fourth end of the common-mode inductor LF1 is grounded through the ferrite bead L2.

[0009] As a further solution of the present invention: the multifunctional fast protection circuit also includes an anti-reverse connection and anti-backflow protection circuit, and an anti-reverse connection and anti-backflow protection circuit is added between the second end of the switch tube Q1 and the positive pole P2 of the output interface. The anti-reverse connection and anti-backflow protection circuit includes a diode D1 and a diode D2. The positive pole of the diode D1 is connected to the second end of the switch tube Q1, the negative pole of the diode D1 is connected to the negative pole of the diode D2 and the positive pole P2 of the output interface, and the positive pole of the diode D2 is grounded.

[0010] As a further solution of the present invention: the multifunctional fast protection circuit also includes an overvoltage detection protection circuit, and an overvoltage detection protection circuit is added between the first end of the switch tube Q1 and the positive pole P1 of the input interface. The overvoltage detection protection circuit includes a diode ZD2, a resistor R5, and a transistor Q3. The cathode of the diode ZD2 is connected to the positive pole P1 of the input interface, the anode of the diode D2 is connected to the first end of the resistor R5 and the base of the transistor Q3, the second end of the resistor R5 is grounded, the collector of the transistor Q3 is connected to the cathode of the diode ZD1, and the emitter of the transistor Q3 is grounded.

[0011] As a further solution of the present invention: the multifunctional fast protection circuit also includes an MCU enabling circuit, the MCU enabling circuit includes a diode D4 and an MCU, the cathode of the diode D4 is connected to the base of the transistor Q3, and the anode of the diode D4 is connected to the MCU.

[0012] As a further solution of the present invention: the multifunctional fast protection circuit also includes a temperature protection control circuit, the temperature protection control circuit includes a thermistor RT1, one end of the thermistor RT1 is grounded, and the other end of the thermistor RT1 is connected to the cathode of the diode ZD1.

[0013] As a further solution of the present invention: the multifunctional fast protection circuit also includes an anti-static protection circuit, and an anti-static protection circuit is added between the second end of the switch tube Q1 and the positive pole P2 of the output interface. The anti-static protection circuit includes a protection tube TVS1, and the A2 end of the protection tube TVS1 is connected to the second point of the switch tube Q1, and the A1 end of the protection tube TVS1 is grounded.

[0014] As a further solution of the present invention: the multifunctional fast protection circuit also includes an output overcurrent and short-circuit protection circuit, and the output overcurrent and short-circuit protection circuit includes a diode D3, the anode of the diode D3 is connected to the cathode of the diode ZD1, and the cathode of the diode D3 is connected to the anode P2 of the output interface.

[0015] As a further solution of the present invention: the diode ZD1 is replaced by a resistor R55.

[0016] As a further solution of the present invention: the multifunctional fast protection circuit also includes an output overcurrent and short-circuit protection circuit, and the output overcurrent and short-circuit protection circuit includes a transistor Q3 and a resistor R8. At this time, the negative electrode P3 of the output interface is connected to one end of the resistor R8 and the emitter of the transistor Q3, the other end of the resistor R8 is grounded, the base of the transistor Q3 is grounded, and the collector of the transistor Q3 is connected to the negative electrode of the diode ZD1.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: after the switch tube Q1 provided in the present invention is turned on, the voltage drop is extremely small, so the loss is extremely small, the heat generation is very small, and no heat sink is required, thereby reducing the cost; a variety of protection circuits are provided, which occupy fewer devices and save costs; a variety of protection circuits such as undervoltage protection circuit, common mode low frequency, high frequency anti-interference circuit, anti-reverse connection, anti-backflow protection circuit, overvoltage detection protection circuit, MCU enabling circuit, temperature protection control circuit, anti-static protection circuit, output overcurrent, short circuit protection circuit, etc. are provided to ensure safe operation, and some protection circuits can be removed according to actual conditions, and the applicability is strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The following is a circuit diagram of an existing common interface input and output control circuit.

[0019] Figure 2 The present invention is a circuit diagram of an existing multiple transistor combination interface input and output control circuit.

[0020] Figure 3 The utility model is a circuit diagram of a multifunctional fast protection circuit.

[0021] Figure 4 The figure is a specific example circuit diagram of a multifunctional fast protection circuit.

[0022] Figure 5 The circuit diagram of different switch tubes of a multifunctional fast protection circuit is shown in FIG.

[0023] Figure 6 The circuit diagram of a multifunctional fast protection circuit is shown below after removing the common-mode low-frequency and high-frequency anti-interference circuits.

[0024] Figure 7 This is the circuit diagram after removing the MCU enabling circuit.

[0025] Figure 8 This is the circuit diagram after removing the overvoltage detection protection circuit.

[0026] Fig. 9 This is a circuit diagram in which resistor R5 replaces diode ZD1.

[0027] Fig.10 This is the circuit diagram after removing the anti-reverse connection and anti-backflow protection circuits.

[0028] Fig.11 This is a circuit diagram in which transistor Q3 and resistor R8 replace diode D3. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] See also Figure 3 , Figure 4 and Figure 5 A multifunctional fast protection circuit includes a switch tube Q1 and a switch tube Q2. The first end of the switch tube Q1 is connected to the first end of a resistor R1, an input interface positive electrode P1, and a first end of a resistor R2. The second end of the switch tube Q1 is connected to the first end of a resistor R3, a second end of a capacitor C1, and an output interface positive electrode P2. The second end of the resistor R3 is grounded. The first end of the capacitor C1 is grounded. The third end of the switch tube Q1 is connected to the first end of a resistor R4 and a second end of the resistor R1. The second end of the resistor R4 is connected to the first end of the switch tube Q2. The second end of the switch tube Q2 is grounded through a resistor R7. The third end of the switch tube Q2 is connected to the positive electrode of a diode ZD1. The negative electrode of the diode ZD1 is connected to the second end of the resistor R2 and a first end of a resistor R6. The second end of the resistor R6 is grounded. The negative electrode P4 of the input interface and the negative electrode P3 of the output interface are both grounded.

[0031] In this example: See Figure 3 , Figure 4 and Figure 5 , the switch tube Q1 can be a PNP transistor or a PMOS tube, and the switch tube Q2 can be an NPN transistor or a digital transistor NPN transistor; The switch tube Q1, resistor R1, resistor R4, switch tube Q2, and resistor R7 constitute the key components of the power switch control output. Figure 3 In the figure, the switch tube Q1 is a PNP transistor, which is a power switch tube that bears current and voltage. When the switch tube Q2 is an NPN transistor, when the base of the NPN transistor is at a high level, the NPN transistor is turned on, pulling down the base voltage of the PNP transistor, and the PNP transistor is turned on. After the PNP transistor is turned on, the voltage drop is very small, so the loss is very small, and the heat is very little. No heat sink is needed, and a transistor with a small package SOT-23 can be used directly.

[0032] Resistor R2, resistor R6, diode ZD1, and switch tube Q2 form an input voltage undervoltage protection circuit. When the voltage input to the positive electrode P1 of the input interface is lower than the lower threshold, the voltage divided on resistor R6 cannot trigger the voltage-stabilizing diode ZD1 to turn on, and the switch tube Q2 does not turn on. When the voltage input to the positive electrode P1 of the input interface is higher than the lower threshold, the voltage divided on resistor R6 can trigger the voltage-stabilizing diode ZD1 to turn on, and the switch tube Q2 is then turned on, further triggering the switch tube Q1 to turn on. The positive electrode P1 of the input interface, the switch tube Q1, and the positive electrode P2 of the output interface form a loop, and the circuit is turned on. Some products have a lower and upper limit operating range for the input voltage. In the non-operating voltage range, the product will be damaged or the product will work abnormally. The undervoltage protection circuit can avoid abnormal operation. Resistor R7 cooperates with diode ZD1 and switch tube Q2 to finely and accurately adjust the turn-on voltage, making the undervoltage protection more accurate.

[0033] See also Figure 4 , the parameters of actual applications are marked for each device. It should be noted that these parameters are only for illustration and actual use is not limited to the parameters shown in the examples.

[0034] See also Figure 5 , this is Figure 3 The evolution of the circuit. In the figure, the switch tube Q2 uses a digital transistor with two resistors inside. The switch tube Q1 uses a PMOS tube, and an additional diode ZD3 is added. When the switch tube Q2 is turned off, the diode ZD3 protects the GS pole of the PMOS tube from being broken down. The PMOS tube can make the power supply power larger, the output current larger, and the heat less. The other design connections and working principles are the same. Figure 3 .

[0035] In this example: See Figure 3 The multifunctional fast protection circuit also includes a common-mode low-frequency and high-frequency anti-interference circuit. A common-mode low-frequency and high-frequency anti-interference circuit is added between the second end of the switch tube Q1 and the output interface positive pole P2. The common-mode low-frequency and high-frequency anti-interference circuit includes a common-mode inductor LF1, a capacitor C2, a ferrite bead L1, and a ferrite bead L2. The first end of the common-mode inductor LF1 is connected to the second end of the switch tube Q1, the second end of the common-mode inductor LF1 is grounded, the third end of the common-mode inductor LF1 is connected to the first end of the ferrite bead L1 and the second end of the capacitor C2, the second end of the ferrite bead L1 is connected to the output interface positive pole P2, the first end of the capacitor C2 is grounded, and the fourth end of the common-mode inductor LF1 is grounded through the ferrite bead L2.

[0036] In actual use, you can choose whether to add common-mode low-frequency and high-frequency anti-interference circuits by removing or installing common-mode inductor LF1, capacitor C2, ferrite bead L1, and ferrite bead L2 according to actual conditions.

[0037] Capacitor C1, common-mode inductor LF1, and capacitor C2 form a π-type common-mode anti-interference circuit. The front-stage circuit of the switching power supply will output medium and high-frequency clutter interference signals, causing conduction and radiation interference to electronic products. By adding this circuit, the interference signals in the medium and low frequency bands are filtered and filtered, so that the output power quality can be purified and improved, and the conduction and radiation of the signal are prevented from interfering with other electronic devices or interfering with the subsequent circuits. Ferrite beads L1 and L2 have the effect of attenuating interference signals at high and ultra-high frequencies, and further eliminate interference in the high-frequency band of the power supply output, so that the power supply product certification can pass EMC EMI, safety regulations, and safety projects. The design of a two-stage segmented barrier is adopted, and the capacitor and inductor π-type parameter ferrite beads are flexibly combined to play a better role in the low-frequency, medium-frequency, and high-frequency full-band.

[0038] In this example: See Figure 3 The multifunctional fast protection circuit also includes an anti-reverse connection and anti-backflow protection circuit. An anti-reverse connection and anti-backflow protection circuit is added between the second end of the switch tube Q1 and the output interface positive pole P2. The anti-reverse connection and anti-backflow protection circuit includes a diode D1 and a diode D2. The positive pole of the diode D1 is connected to the second end of the switch tube Q1, the negative pole of the diode D1 is connected to the negative pole of the diode D2 and the output interface positive pole P2, and the positive pole of the diode D2 is grounded.

[0039] The anti-reverse connection and anti-backflow protection circuits can be connected or not according to the actual situation by removing or installing diodes D1 and D2.

[0040] The diode D2 is cut off in the normal state and does not affect the use of the circuit. In the traditional circuit, when P2 is the positive pole of the power supply and P3 is the negative pole of the power supply (GND), it must not be connected in reverse. If it is connected in reverse, there will be no output or the circuit will be burned. Based on the addition of the anti-reverse connection diode D2, when P2 is the negative pole and P3 is the positive pole, the diode D2 is forward-conducted, which prevents the circuit from being damaged due to incorrect operation and further protects the reliability of the circuit. The diode D1 is an anti-backflow diode. When the input and output of P1, P2, P3, and P4 are connected in reverse, it will not cause damage to the power supply or the load at the output end. When P2 is the output end of the power supply, if the user regards P2 as the input end, add positive voltage from P2 and add negative pole to P3. Although the added power supply has the correct polarity, after the input and output are connected in reverse, the diode D1 has the unidirectional conduction characteristic, and the voltage will not be input to the switch tube Q1, protecting the safety of the switch tube Q1 and other components. The resistor R3 is a load resistor, which provides a small bias current path for the diodes D1 and D2 to stabilize the circuit working point.

[0041] In this example: See Figure 3The multifunctional fast protection circuit also includes an overvoltage detection protection circuit. An overvoltage detection protection circuit is added between the first end of the switch tube Q1 and the input interface positive electrode P1. The overvoltage detection protection circuit includes a diode ZD2, a resistor R5, and a transistor Q3. The cathode of the diode ZD2 is connected to the input interface positive electrode P1, the anode of the diode D2 is connected to the first end of the resistor R5 and the base of the transistor Q3, the second end of the resistor R5 is grounded, the collector of the transistor Q3 is connected to the cathode of the diode ZD1, and the emitter of the transistor Q3 is grounded.

[0042] The overvoltage detection protection circuit can be connected or not according to the actual situation, by removing or installing the diode ZD2, the resistor R5, and the transistor Q3. The switch tube Q3 can be an NPN transistor or a digital transistor NPN transistor.

[0043] When the voltage output by the positive electrode P1 of the input interface is too large and exceeds the upper threshold, the voltage stabilizing diode ZD2 is turned on, causing the transistor Q3 to be turned on, thereby causing the cathode of the diode ZD1 to be at a low level, the switch tube Q2 to be turned off, the switch tube Q1 to be turned off, and the power supply circuit to be disconnected, thereby playing an overvoltage protection role.

[0044] In this example: See Figure 3 The multifunctional fast protection circuit also includes an MCU enabling circuit, which includes a diode D4 and an MCU, wherein the cathode of the diode D4 is connected to the base of the transistor Q3, and the anode of the diode D4 is connected to the MCU.

[0045] The MCU enabling circuit can be connected or not according to the actual situation by removing or installing the diode D4 and the MCU.

[0046] When the IO port of the MCU outputs a high level, the base of the transistor Q3 is at a high level, and the transistor Q3 is turned on, which makes the cathode of the diode ZD1 at a low level, the switch tube Q2 is turned off, the switch tube Q1 is turned off, and the power supply circuit is disconnected. Conversely, when the IO port of the MCU outputs a low level, the transistor Q3 is turned off, the switch tube Q2 is turned on, the switch tube Q1 is turned on, and the power supply circuit is turned on. The MCU controls the output interface positive electrode P2 to switch between output and no output. In this way, it can be flexibly controlled according to the use of the output load. For example, when the output power is not needed, there is no need to manually unplug or remove P1, P2, P3, P4 to cut off the power, avoiding the danger of live operation, especially when working with high current to avoid sparks and damage to circuit components.

[0047] In this example: See Figure 3 The multifunctional fast protection circuit also includes a temperature protection control circuit, which includes a thermistor RT1, one end of the thermistor RT1 is grounded, and the other end of the thermistor RT1 is connected to the cathode of the diode ZD1.

[0048] The temperature protection control circuit can be connected or not according to the actual situation by removing or installing the thermistor RT1.

[0049] The temperature protection control circuit is mainly for the interface control circuit with large current output. In order to use the circuit in special working conditions (such as high temperature boxes, high temperature ovens, high temperature motors, and high temperature electrical products), the circuit will not be burned even if the environment is used to the extreme. The thermistor RT1 is installed near the switch tube Q1 to detect the temperature of the switch tube Q1. The thermistor RT1 can also be close to the highest heat source of the actual electrical product. When the heat is too high, higher than the temperature value set by the thermistor RT1, the resistance value of the thermistor RT1 changes logarithmically or linearly, and the resistance value becomes smaller. The thermistor RT1 and the resistor R6 are fixed in parallel. The resistance value of the thermistor RT1 becomes smaller, so that the resistance value of the thermistor RT1 and the resistor R6 in parallel will also become smaller. After the resistor R2 and the parallel resistor (RT1 / / R6) are connected in series and divided, the voltage at the cathode of the diode ZD1 decreases. When it is lower than the breakdown voltage of the diode ZD1, the diode ZD1 is closed and cut off, the switch tube Q2 changes from on to off, and the switch tube Q1 changes from on to off, and there is no output voltage. It plays the role of over-temperature protection and shuts down the output. When the product temperature drops and does not exceed the temperature value set by thermistor RT1, the circuit automatically resumes output.

[0050] In this example: See Figure 3 The multifunctional fast protection circuit also includes an anti-static protection circuit. An anti-static protection circuit is added between the second end of the switch tube Q1 and the positive pole P2 of the output interface. The anti-static protection circuit includes a protection tube TVS1. The A2 end of the protection tube TVS1 is connected to the second point of the switch tube Q1, and the A1 end of the protection tube TVS1 is grounded.

[0051] The anti-static protection circuit can be connected or not according to the actual situation, by removing or installing the protection tube TVS1.

[0052] The ports of electronic products are prone to generate high static ESD during use, at the moment of plugging and unplugging, or when the human body carries static electricity, or when there is friction during transportation. The certification room will also perform ESD discharge experiments on the products using an electrostatic gun. The protection tube TVS1 is a bidirectional transient suppression diode. The protection tube TVS1 has an extremely fast action time and a large suppression power. It can instantly absorb large surge currents and play a role in electrostatic protection. The difference between the use of a bidirectional transient suppression diode and the industry's old practice of a single-phase transient suppression diode is that the bidirectional transient suppression diode can play a role regardless of whether positive (+KV) static electricity or negative (-KV) static electricity appears on the P2 or P3 port. The protection tube TVS1 can play a role. The unidirectional TVS tube can only prevent positive static electricity (+KV) and has no protection against negative static electricity.

[0053] In this example: See Figure 3 The multifunctional fast protection circuit also includes an output overcurrent and short-circuit protection circuit, which includes a diode D3, the anode of the diode D3 is connected to the cathode of the diode ZD1, and the cathode of the diode D3 is connected to the anode P2 of the output interface.

[0054] The overcurrent and short-circuit protection circuits can be connected or not according to the actual situation by removing or installing the diode D3.

[0055] When the positive electrode P2 of the output interface is short-circuited to the negative electrode P3 of the output interface, that is, P2 and P3 are directly connected or equivalently connected, the high-level voltage output by P2 is short-circuited to GND (ground), ignoring the voltage of diode D3, the on-state voltage drop of diode D3 is 0.3-0.6V, the cathode of diode ZD1 is low level, diode ZD1 is cut off, the switch tubes Q2 and Q1 are cut off, the power supply circuit is disconnected, and short-circuit protection is achieved without burning any parts of the circuit. When the short circuit between output P2 and P3 is released, the circuit returns to its original state and the voltage is re-supplied. The overcurrent short-circuit protection work and protection release switch back and forth quickly, the response time is extremely fast, and the stress on the circuit switch tube Q1 to close and turn on is small. Conventional existing short-circuit solutions can only rely on the power supply itself to withstand the stress power consumption of large current. After the short circuit, the power switch tube will also heat up seriously, which is unsafe for the power device switch tube Q1. This circuit has the characteristics of zero heat and zero power consumption in the short circuit.

[0056] In this example: See Figure 3 , Figure 6 , Figure 7 , Figure 8 and Fig. 9 , diode ZD1 is replaced by resistor R55.

[0057] Figure 6 This is a circuit diagram of a multifunctional fast protection circuit after removing the common-mode low-frequency and high-frequency anti-interference circuits. Figure 7 exist Figure 6 Based on removing the MCU enabling circuit, Figure 8 exist Figure 7 Based on removing the overvoltage detection protection circuit, Fig. 9 exist Figure 8 On the basis of, the diode ZD1 is replaced by the resistor R55.

[0058] Resistors R2 and R6 form a series voltage divider, and the voltage on resistor R6 is divided in series through resistor R55, switch tube Q2, and resistor R7. By adjusting any resistance value of resistors R55 and R7, the set voltage value can be achieved, which plays the role of setting undervoltage protection.

[0059] In this example: See Fig.10 , Fig.11The multifunctional fast protection circuit also includes an output overcurrent and short-circuit protection circuit, which includes a transistor Q3 and a resistor R8. At this time, the negative electrode P3 of the output interface is connected to one end of the resistor R8 and the emitter of the transistor Q3, the other end of the resistor R8 is grounded, the base of the transistor Q3 is grounded, and the collector of the transistor Q3 is connected to the negative electrode of the diode ZD1.

[0060] Fig.10 exist Fig. 9 Remove the anti-reverse connection and anti-backflow protection circuits on the basis of Fig.11 exist Fig. 9 Based on the above, transistor Q3 and resistor R8 are used to replace diode D3. Resistor R8 and transistor Q3 form an overcurrent or current limiting protection function for output P2. Resistor R8 is used to set a fixed value of the output P2 load current. When the load current consumption at P2 and P3 ends reaches or exceeds the set current of resistor R8, the voltage across resistor R8 reaches the BE pole turn-on voltage of transistor Q3, prompting the CE pole of transistor Q3 to be turned on to ground (GND). The voltage on resistor R6 is turned on to ground by transistor Q3, and switch tubes Q2 and Q1 are turned off. It plays the role of current limiting protection. On the contrary, when the load current consumption at P2 and P3 ends is less than the set current of resistor R8, transistor Q3 is not turned on, and switch tubes Q2 and Q1 are turned on, and there is an output voltage to the P2 port. In addition to the function of current limiting protection, this circuit also has the function of short-circuit protection of output port P2. The principle of short-circuit protection is the same, that is, current limiting protection is more refined than short-circuit protection in current protection level, and current limiting protection has priority over short-circuit protection.

[0061] After the switch tube Q1 provided in the present invention is turned on, the voltage drop is extremely small, so the loss is extremely small, the heat is very little, and there is no need for a heat sink, which reduces the cost; multiple protection circuits are provided to occupy fewer devices, saving costs; undervoltage protection circuits, common mode low frequency, high frequency anti-interference circuits, anti-reverse connection, anti-backflow protection circuits, overvoltage detection protection circuits, MCU enabling circuits, temperature protection control circuits, anti-static protection circuits, output overcurrent, short circuit protection circuits and other protection circuits are provided to ensure safe operation, and some protection circuits can be removed according to actual conditions, so the applicability is strong.

[0062] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered as exemplary and non-restrictive in all respects.

[0063] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A multifunctional fast protection circuit, characterized in that: The multifunctional fast protection circuit includes a switch tube Q1 and a switch tube Q2. The first end of the switch tube Q1 is connected to the first end of the resistor R1, the input interface positive electrode P1, and the first end of the resistor R2. The second end of the switch tube Q1 is connected to the first end of the resistor R3, the second end of the capacitor C1, and the output interface positive electrode P2. The second end of the resistor R3 is grounded, and the first end of the capacitor C1 is grounded. The third end of the switch tube Q1 is connected to the first end of the resistor R4 and the second end of the resistor R1. The second end of the resistor R4 is connected to the first end of the switch tube Q2. The second end of the switch tube Q2 is grounded through the resistor R7. The third end of the switch tube Q2 is connected to the positive electrode of the diode ZD1. The negative electrode of the diode ZD1 is connected to the second end of the resistor R2 and the first end of the resistor R6. The second end of the resistor R6 is grounded. The negative electrode P4 of the input interface and the negative electrode P3 of the output interface are both grounded.

2. The multifunctional fast protection circuit according to claim 1, characterized in that: The multifunctional fast protection circuit also includes a common-mode low-frequency and high-frequency anti-interference circuit. A common-mode low-frequency and high-frequency anti-interference circuit is added between the second end of the switch tube Q1 and the positive pole P2 of the output interface. The common-mode low-frequency and high-frequency anti-interference circuit includes a common-mode inductor LF1, a capacitor C2, a ferrite bead L1, and a ferrite bead L2. The first end of the common-mode inductor LF1 is connected to the second end of the switch tube Q1, the second end of the common-mode inductor LF1 is grounded, the third end of the common-mode inductor LF1 is connected to the first end of the ferrite bead L1 and the second end of the capacitor C2, the second end of the ferrite bead L1 is connected to the positive pole P2 of the output interface, the first end of the capacitor C2 is grounded, and the fourth end of the common-mode inductor LF1 is grounded through the ferrite bead L2.

3. The multifunctional fast protection circuit according to claim 1, characterized in that: The multifunctional fast protection circuit also includes an anti-reverse connection and anti-backflow protection circuit. An anti-reverse connection and anti-backflow protection circuit is added between the second end of the switch tube Q1 and the output interface positive pole P2. The anti-reverse connection and anti-backflow protection circuit includes a diode D1 and a diode D2. The positive pole of the diode D1 is connected to the second end of the switch tube Q1, the negative pole of the diode D1 is connected to the negative pole of the diode D2 and the output interface positive pole P2, and the positive pole of the diode D2 is grounded.

4. The multifunctional fast protection circuit according to claim 1, characterized in that: The multifunctional fast protection circuit also includes an overvoltage detection protection circuit. An overvoltage detection protection circuit is added between the first end of the switch tube Q1 and the positive pole P1 of the input interface. The overvoltage detection protection circuit includes a diode ZD2, a resistor R5, and a transistor Q3. The cathode of the diode ZD2 is connected to the positive pole P1 of the input interface, the anode of the diode D2 is connected to the first end of the resistor R5 and the base of the transistor Q3, the second end of the resistor R5 is grounded, the collector of the transistor Q3 is connected to the cathode of the diode ZD1, and the emitter of the transistor Q3 is grounded.

5. The multifunctional fast protection circuit according to claim 4, characterized in that: The multifunctional fast protection circuit also includes an MCU enabling circuit, which includes a diode D4 and an MCU. The cathode of the diode D4 is connected to the base of the transistor Q3, and the anode of the diode D4 is connected to the MCU.

6. The multifunctional fast protection circuit according to claim 1, characterized in that: The multifunctional fast protection circuit also includes a temperature protection control circuit, which includes a thermistor RT1 , one end of the thermistor RT1 is grounded, and the other end of the thermistor RT1 is connected to the cathode of the diode ZD1 .

7. The multifunctional fast protection circuit according to claim 1, characterized in that: The multifunctional fast protection circuit also includes an anti-static protection circuit. An anti-static protection circuit is added between the second end of the switch tube Q1 and the positive pole P2 of the output interface. The anti-static protection circuit includes a protection tube TVS1. The A2 end of the protection tube TVS1 is connected to the second point of the switch tube Q1, and the A1 end of the protection tube TVS1 is grounded.

8. The multifunctional fast protection circuit according to claim 1, characterized in that: The multifunctional fast protection circuit also includes an output overcurrent and short circuit protection circuit, which includes a diode D3, the anode of the diode D3 is connected to the cathode of the diode ZD1, and the cathode of the diode D3 is connected to the anode P2 of the output interface.

9. The multifunctional fast protection circuit according to any one of claims 1 to 8, characterized in that: The diode ZD1 is replaced by a resistor R55.

10. The multifunctional fast protection circuit according to claim 1, characterized in that: The multifunctional fast protection circuit also includes an output overcurrent and short-circuit protection circuit, which includes a transistor Q3 and a resistor R8. At this time, the output interface negative electrode P3 is changed from being directly grounded to the output interface negative electrode P3 being connected to one end of the resistor R8 and the emitter of the transistor Q3, the other end of the resistor R8 is grounded, the base of the transistor Q3 is grounded, and the collector of the transistor Q3 is connected to the negative electrode of the diode ZD1.

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