A high-precision overcurrent short-circuit protection circuit

Abstract

The present invention belongs to the field of circuit technology, and relates to a high-precision overcurrent short-circuit protection circuit, including a surge suppression circuit, which is electrically connected between an external input terminal and an external output terminal; a bootstrap circuit, whose output terminal is electrically connected to the driving of the surge suppression circuit; a sampling circuit, whose input terminal is electrically connected to the external output terminal; a comparison circuit, whose input terminal is electrically connected to the output terminal of the sampling circuit, and the output terminal of the comparison circuit is electrically connected to the input terminal of the logic control circuit; a logic control circuit, whose output terminal is electrically connected to the driving of the surge suppression circuit, and is used to lower the driving voltage of the surge suppression circuit in an overcurrent working state; a power supply circuit, which is electrically connected to the external input terminal, the bootstrap circuit, the sampling circuit, the comparison circuit and the logic control circuit, respectively, and is used to ensure the normal power supply of the subsequent circuit. The present invention effectively reduces the power consumption of the surge suppression circuit during continuous overcurrent and short circuit, and improves the reliability of the product.

Description

Technical Field

[0001] The invention belongs to the technical field of circuits, and in particular relates to a high-precision overcurrent short-circuit protection circuit. Background Art

[0002] The traditional overvoltage linear surge suppression circuit has no overcurrent or short-circuit protection. When an overcurrent occurs in the downstream module, the output current exceeds the rated current, resulting in a reduction in the module's service life. When the overcurrent is severe or a short circuit occurs, the current flowing through the power MOSFET is too large, exceeding the junction temperature of the power MOSFET, causing the MOSFET to burn out and the surge suppression module to fail, posing a great safety hazard to downstream equipment. Summary of the invention

[0003] In view of this, the present invention provides a high-precision over-current short-circuit protection circuit to solve the above-mentioned technical problems.

[0004] The technical solution of the present invention is:

[0005] A high-precision overcurrent short-circuit protection circuit, comprising:

[0006] A surge suppression circuit is electrically connected between the external input terminal and the external output terminal;

[0007] A bootstrap circuit, used for providing a driving voltage for the surge suppression circuit under normal working conditions, wherein an output end of the bootstrap circuit is electrically connected to a driving voltage of the surge suppression circuit;

[0008] A sampling circuit, used for extracting an output current signal of an external output terminal and converting the current signal into a voltage signal, wherein an input terminal of the sampling circuit is electrically connected to the external output terminal;

[0009] A comparison circuit, used for receiving a voltage signal sent by the sampling circuit, comparing the voltage signal with a reference voltage, and sending the comparison result to the logic control circuit, wherein the input end of the comparison circuit is electrically connected to the output end of the sampling circuit, and the output end of the comparison circuit is electrically connected to the input end of the logic control circuit;

[0010] A logic control circuit, used for controlling the on and off of the surge suppression circuit, wherein the output end of the logic control circuit is electrically connected to the driving voltage of the surge suppression circuit, and is used for lowering the driving voltage of the surge suppression circuit in an overcurrent working state;

[0011] The power supply circuit is electrically connected to the external input terminal, the bootstrap circuit, the sampling circuit, the comparison circuit and the logic control circuit respectively, and is used to ensure the normal power supply of the subsequent circuit.

[0012] Preferably, the surge suppression circuit comprises:

[0013] At least two clamping units connected in parallel, the clamping units comprising:

[0014] A first MOSFET tube, wherein the source of the first MOSFET tube is electrically connected to the external output terminal, the drain of the first MOSFET tube is electrically connected to the external input terminal, the gate of the first MOSFET tube is electrically connected to one end of a first capacitor, the other end of the first capacitor is grounded, an end of the first capacitor facing away from the ground end is electrically connected to one end of a seventeenth resistor, and the other end of the seventeenth resistor is electrically connected to the source of the first MOSFET tube.

[0015] Preferably, the external input terminal is electrically connected to one end of a second capacitor, and the other end of the second capacitor is grounded; the external output terminal is electrically connected to one end of a third capacitor, and the other end of the third capacitor is grounded.

[0016] Preferably, the power supply circuit comprises:

[0017] A first power supply circuit is used to provide a stable voltage for the overcurrent protection circuit to ensure that the overcurrent protection circuit is continuously online. The first power supply circuit includes a first resistor with one end electrically connected to the external input terminal, the other end of the first resistor is electrically connected to the cathode of the first voltage regulator tube, and the anode of the first voltage regulator tube is grounded; the first power supply circuit also includes a second resistor with one end electrically connected to the external input terminal, the other end of the second resistor is electrically connected to the cathode of the first voltage regulator tube; the cathode of the first voltage regulator tube is electrically connected to the base of the first triode, the collector of the first triode is electrically connected to the external input terminal, the emitter of the first triode is electrically connected to one end of the fourth capacitor, and the other end of the fourth capacitor is grounded; the emitter of the first triode is also electrically connected to one end of the third resistor and the positive power supply interface of the operational amplifier, the other end of the third resistor is electrically connected to the first end of the integrated circuit, the integrated circuit is used to provide a reference voltage, the second end of the integrated circuit is electrically connected to the first input end of the comparison circuit, and the third end of the integrated circuit is grounded;

[0018] The second power supply circuit is used to provide a stable voltage to the subsequent circuit to ensure the normal power supply of the subsequent circuit. The second power supply circuit includes a fourth resistor with one end electrically connected to the external input terminal, and the other end of the fourth resistor is electrically connected to one end of a fifth capacitor, and the other end of the fifth capacitor is grounded; the second power supply circuit also includes a fifth resistor with one end electrically connected to the external input terminal, and the other end of the fifth resistor is electrically connected to an end of the fifth capacitor away from the ground terminal; a sixth resistor with one end electrically connected to the external input terminal, and the other end of the sixth resistor is electrically connected to an end of the fifth capacitor away from the ground terminal; a second transistor, the collector of the second transistor is electrically connected to the external input terminal, The base of the second transistor is electrically connected to an end of the fifth capacitor facing away from the ground end, the emitter of the second transistor is electrically connected to one end of the sixth capacitor, and the other end of the sixth capacitor is grounded; the base of the second transistor is electrically connected to the anode of the first diode, the cathode of the first diode is electrically connected to the cathode of the second voltage regulator tube, and the anode of the second voltage regulator tube is grounded; the emitter of the second transistor is electrically connected to one end of the seventh capacitor and the positive power supply interface of the comparator, and the other end of the seventh capacitor is grounded; the base of the second transistor is also electrically connected to the first reference voltage interface end of the logic control circuit, and the emitter of the second transistor is electrically connected to the second reference voltage interface end of the logic control circuit.

[0019] Preferably, the sampling circuit comprises:

[0020] An operational amplifier, a positive power supply interface of the operational amplifier is electrically connected to the emitter of the first transistor, and a negative power supply interface of the operational amplifier is grounded; a first input terminal of the operational amplifier is electrically connected to one end of a seventh resistor, and the other end of the seventh resistor is grounded; a second input terminal of the operational amplifier is electrically connected to one end of an eighth capacitor, and the other end of the eighth capacitor is grounded; the second input terminal of the operational amplifier is also electrically connected to one end of the eighth resistor, and the other end of the eighth resistor is grounded; the second input terminal of the operational amplifier is also electrically connected to one end of a ninth resistor, and the other end of the ninth resistor is electrically connected to one end of a tenth resistor, and the other end of the tenth resistor is grounded; an end of the tenth resistor away from the ground terminal is also electrically connected to one end of the ninth capacitor, and the other end of the ninth capacitor is electrically connected to an external output terminal; an end of the seventh resistor away from the ground terminal is electrically connected to one end of an eleventh resistor, and the other end of the eleventh resistor is electrically connected to the output terminal of the operational amplifier, an end of the seventh resistor away from the ground terminal is electrically connected to one end of the tenth capacitor, and the other end of the tenth capacitor is electrically connected to the output terminal of the operational amplifier, and the output terminal of the operational amplifier is electrically connected to the second input terminal of the comparison circuit.

[0021] Preferably, the comparison circuit comprises:

[0022] A comparator, wherein the positive power supply interface of the comparator is electrically connected to the emitter of the second transistor, and the negative power supply interface of the comparator is grounded; the first input terminal of the comparator is electrically connected to one end of a twelfth resistor, and the other end of the twelfth resistor is electrically connected to the second end of the integrated circuit; the second input terminal of the comparator is electrically connected to one end of a thirteenth resistor, and the other end of the thirteenth resistor is electrically connected to the output end of the sampling circuit; the second input terminal of the comparator is also electrically connected to one end of a fourteenth resistor, and the other end of the fourteenth resistor is electrically connected to the anode of the second diode, the cathode of the second diode is electrically connected to the output terminal of the comparator, and the output terminal of the comparator is also electrically connected to the input terminal of the logic control circuit.

[0023] Preferably, the logic control circuit comprises:

[0024] a second MOSFET tube, wherein the source of the second MOSFET tube is electrically connected to the base of the second triode, the drain of the second MOSFET tube is grounded, and the gate of the second MOSFET tube is electrically connected to the output end of the comparison circuit;

[0025] a third MOSFET tube, a source electrode of the second MOSFET tube is electrically connected to one end of a fifteenth resistor, the other end of the fifteenth resistor is electrically connected to the gate electrode of the first MOSFET tube as an output end, a drain electrode of the third MOSFET tube is grounded, and the gate electrode of the third MOSFET tube is electrically connected to the gate electrode of the second MOSFET tube;

[0026] a fourth MOSFET tube, a source of the second MOSFET tube is electrically connected to one end of a sixteenth resistor, the other end of the sixteenth resistor is electrically connected to the emitter of the second transistor, the drain of the fourth MOSFET tube is grounded, and the gate of the fourth MOSFET tube is electrically connected to the gate of the second MOSFET tube.

[0027] Preferably, the fourth resistor, the fifth resistor, the sixth resistor and the fifth capacitor have a plurality of different replacement specifications for adjusting the startup delay time of the system.

[0028] Preferably, the second power supply circuit is replaced by a timing circuit.

[0029] The invention provides a high-precision overcurrent short-circuit protection circuit, which has the advantage of suppressing output current by accurately detecting surges. When the output current exceeds the set current, the main power MOSFET tube in the clamping circuit is turned off to meet the requirements of the protection module.

[0030] Compared with the prior art, the present invention can flexibly magnify the magnification and relatively freely scale the error, provide overcurrent protection of different currents for modules of different power levels, reduce the power consumption of overcurrent protection, and effectively reduce the power consumption of surge suppression circuits during continuous overcurrent and short circuit by adjusting the power-on delay time, thereby improving the reliability of the product, having strong practicality and being worthy of promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the overall circuit diagram of the present invention;

[0032] Figure 2 It is a principle block diagram of the present invention;

[0033] Figure 3 A power supply circuit for the overcurrent protection circuit of the present invention;

[0034] Figure 4 A power supply circuit for the surge suppression circuit of the present invention;

[0035] Figure 5 A comparison circuit of the present invention;

[0036] Figure 6 A logic control circuit of the present invention;

[0037] Figure 7 This is the sampling circuit of the present invention. DETAILED DESCRIPTION

[0038] The present invention provides a high-precision overcurrent short-circuit protection circuit. Figures 1 to 7 The present invention is described with reference to the structural schematic diagram of FIG.

[0039] Example 1

[0040] A high-precision over-current short-circuit protection circuit, the circuit diagram is shown in Figure 1 and Figure 2 As shown, it includes a surge suppression circuit, which is electrically connected between an external input terminal and an external output terminal. The voltage surge suppression circuit is a non-isolated linear circuit. When the input voltage is higher than the set voltage, the voltage surge suppression circuit works to clamp the output voltage within the set voltage. The portion higher than the set voltage is absorbed by the voltage surge suppression circuit and released in the form of heat.

[0041] The surge suppression circuit includes:

[0042] At least two clamping units connected in parallel, the clamping units comprising:

[0043] a first MOSFET tube, wherein the source of the first MOSFET tube is electrically connected to the external output terminal, the drain of the first MOSFET tube is electrically connected to the external input terminal, the gate of the first MOSFET tube is electrically connected to one end of a first capacitor C2A, the other end of the first capacitor C2A is grounded, the end of the first capacitor C2A away from the ground end is electrically connected to one end of a seventeenth resistor R2A, and the other end of the seventeenth resistor R2A is electrically connected to the source of the first MOSFET tube;

[0044] Also includes:

[0045] A bootstrap circuit, a sampling circuit, a comparison circuit, a power supply circuit and a logic control circuit, wherein the bootstrap circuit is used to provide a gate drive voltage for the clamping unit under normal working conditions, and the output end of the bootstrap circuit is electrically connected to the gate of the first MOSFET tube;

[0046] The sampling circuit is used to extract the output current signal of the external output terminal and convert the current signal into a voltage signal, the input terminal of the sampling circuit is electrically connected to the external output terminal, and the output terminal of the sampling circuit is electrically connected to the input terminal of the comparison circuit;

[0047] The comparison circuit is used to receive the voltage signal sent by the sampling circuit, compare the voltage signal with the reference voltage, and send the comparison result to the logic control circuit. The output end of the comparison circuit is electrically connected to the input end of the logic control circuit. The logic control circuit is used to control the on and off of the surge suppression circuit. The output end of the logic control circuit is electrically connected to the gate of the first MOSFET tube, and is used to lower the gate drive voltage of the clamping unit in the overcurrent working state.

[0048] The power supply circuit is electrically connected to the bootstrap circuit, sampling circuit, comparison circuit and logic control circuit respectively, and is used to ensure normal power supply of the subsequent circuit. The input end of the power supply circuit is electrically connected to the external input end.

[0049] Further, the external input terminal is electrically connected to one end of the second capacitor CA, and the other end of the second capacitor CA is grounded; the external output terminal is electrically connected to one end of the third capacitor CB, and the other end of the third capacitor CB is grounded.

[0050] Furthermore, the power supply circuit includes:

[0051] First power supply circuit, see Figure 3 As shown, the overcurrent protection circuit power supply part is used to provide a stable voltage for the overcurrent protection circuit to ensure that the overcurrent protection circuit is continuously online, and is composed of a first resistor R1, a second resistor R2, a first transistor VT1, a first voltage regulator DZ1 and a fourth capacitor C1.

[0052] The first power supply circuit includes a first resistor R1 with one end electrically connected to the external input terminal, the other end of the first resistor R1 is electrically connected to the cathode of the first voltage regulator DZ1, and the anode of the first voltage regulator DZ1 is grounded. The first power supply circuit also includes a second resistor R2 with one end electrically connected to the external input terminal, the other end of the second resistor R2 is electrically connected to the cathode of the first voltage regulator DZ1; the cathode of the first voltage regulator DZ1 is electrically connected to the base of the first transistor VT1, the collector of the first transistor VT1 is electrically connected to the external input terminal, the emitter of the first transistor VT1 is electrically connected to one end of the fourth capacitor C1, and the other end of the fourth capacitor C1 is grounded; the emitter of the first transistor VT1 is also electrically connected to one end of the third resistor R3 and the positive power supply interface of the operational amplifier, the other end of the third resistor R3 is electrically connected to the first end of the integrated circuit IC1, the integrated circuit IC1 is used to provide a reference voltage, the second end of the integrated circuit IC1 is electrically connected to the first input end of the comparison circuit, and the third end of the integrated circuit IC1 is grounded.

[0053] Among them, the first resistor R1 and the second resistor R2 are the current limiting resistors of the base of the first transistor VT1, and the first voltage regulator DZ1 is the limiting voltage regulator diode output by the base of the first transistor VT1. The integrated circuit IC1 provides a reference signal Vref1 for the overcurrent protection circuit, and the third resistor R3 is the current limiting resistor of the integrated circuit IC1, and the model of the integrated circuit IC1 is TL431.

[0054] Second power supply circuit, see Figure 4As shown, the power supply part of the surge suppression circuit is used to provide a stable voltage to the subsequent circuit to ensure the normal power supply of the subsequent circuit. The power supply circuit is composed of a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a second transistor VT2, a first diode D1, a second voltage regulator DZ2 for voltage stabilization, a fifth capacitor C2, a sixth capacitor C3 for outputting voltage, and a seventh capacitor C4. The structure of the second power supply circuit includes a fourth resistor R4 electrically connected to the external input terminal at one end, the other end of the fourth resistor R4 is electrically connected to one end of the fifth capacitor C2, and the other end of the fifth capacitor C2 is grounded; the second power supply circuit also includes a fifth resistor R5 electrically connected to the external input terminal at one end, the other end of the fifth resistor R5 is electrically connected to an end of the fifth capacitor C2 away from the ground terminal; a sixth resistor R6 electrically connected to the external input terminal at one end, the other end of the sixth resistor R6 is electrically connected to an end of the fifth capacitor C2 away from the ground terminal; a second transistor VT2, the collector of the second transistor VT2 is electrically connected to the external input terminal, the base of the second transistor VT2 is away from the ground terminal of the fifth capacitor C2, and the collector of the second transistor VT2 is electrically connected to the external input terminal. One end of the ground terminal is electrically connected, the emitter of the second triode VT2 is electrically connected to one end of the sixth capacitor C3, and the other end of the sixth capacitor C3 is grounded; the base of the second triode VT2 is electrically connected to the anode of the first diode D1, the cathode of the first diode D1 is electrically connected to the cathode of the second voltage-stabilizing tube DZ2, and the anode of the second voltage-stabilizing tube DZ2 is grounded; the emitter of the second triode VT2 is electrically connected to one end of the seventh capacitor C4 and the positive power supply interface of the comparator, and the other end of the seventh capacitor C4 is grounded; the base of the second triode VT2 is also electrically connected to the first reference voltage interface terminal of the logic control circuit, and the emitter of the second triode VT2 is electrically connected to the second reference voltage interface terminal of the logic control circuit.

[0055] Among them, the fourth resistor R4, the fifth resistor R5, and the sixth resistor R6 are the base current limiting resistors of the second transistor VT2, the second voltage regulator DZ2 is the limiting voltage regulator diode output by the base of the transistor, and the first diode D1 is a diode for high and low temperature compensation temperature drift. The fifth capacitor C2 and the fourth resistor R4, the fifth resistor R5, and the sixth resistor R6 form a startup power supply delay circuit, and by adjusting its size, the startup power supply delay time of the entire system can be changed.

[0056] For further information, see Figure 7 As shown, the function of the sampling circuit is to extract the sampling signal, convert the current signal into a voltage signal and send it to the comparison circuit.

[0057] The sampling circuit comprises:

[0058] The operational amplifier IC2A, the positive power supply interface of the operational amplifier is electrically connected to the emitter of the first transistor VT1, and the negative power supply interface of the operational amplifier is grounded; the first input terminal of the operational amplifier IC2A is electrically connected to one end of the seventh resistor R13, and the other end of the seventh resistor R13 is grounded; the second input terminal of the operational amplifier IC2A is electrically connected to one end of the eighth capacitor C7, and the other end of the eighth capacitor C7 is grounded; the second input terminal of the operational amplifier IC2A is also electrically connected to one end of the eighth resistor R14, and the other end of the eighth resistor R14 is grounded; the second input terminal of the operational amplifier IC2A is also electrically connected to one end of the ninth resistor R15, and the other end of the ninth resistor R15 is connected to the tenth resistor R16 one end of the tenth resistor R16 is electrically connected to the ground, the other end of the tenth resistor R16 is grounded, and the tenth resistor R16 is a current sampling resistor; the end of the tenth resistor R16 away from the ground end is also electrically connected to one end of the ninth capacitor CC, and the other end of the ninth capacitor CC is electrically connected to the external output end; the end of the seventh resistor R13 away from the ground end is electrically connected to one end of the eleventh resistor R10, and the other end of the eleventh resistor R10 is electrically connected to the output end of the operational amplifier IC2A, the end of the seventh resistor R13 away from the ground end is electrically connected to one end of the tenth capacitor C6, and the other end of the tenth capacitor C6 is electrically connected to the output end of the operational amplifier IC2A, and the output end of the operational amplifier IC2A is electrically connected to the second input end of the comparison circuit.

[0059] Among them, the eleventh resistor R10, the seventh resistor R13, the eighth resistor R14, and the ninth resistor R15 form a differential amplifier circuit, which converts the current signal flowing through the tenth resistor R16 into a voltage signal, and then outputs the voltage. Adjusting the eleventh resistor R10 can change the output amplification factor, and can flexibly adjust the output voltage and change the overcurrent point. Secondly, adjusting the tenth resistor R16 can also change the module overcurrent point. The tenth capacitor C6 and the eleventh resistor R10 form an RC parallel network to speed up the response speed. The eighth capacitor C7 is a filter capacitor to eliminate noise signals during the sampling process, improve the anti-interference of the sampling signal, and make the module more reliable and stable. The resistors and capacitors in the figure are all of high-precision grade, and the operational amplifier IC2A is a high-speed operational amplifier, which can effectively improve the response speed and sampling accuracy of the sampling circuit.

[0060] The tenth resistor R16 is used for sampling, and it can also be changed to a plurality of resistors connected in parallel for sampling.

[0061] For further information, see Figure 5 As shown, the function of the comparison circuit is to send the comparison voltage signal to the logic control circuit, including:

[0062] A comparator IC3A, a positive power supply interface of the comparator IC3A is electrically connected to the emitter of the second transistor VT2, and a negative power supply interface of the comparator IC3A is grounded; a first input terminal of the comparator IC3A is electrically connected to one end of a twelfth resistor R12, and the other end of the twelfth resistor R12 is electrically connected to the second end of the integrated circuit IC1; a second input terminal of the comparator IC3A is electrically connected to one end of a thirteenth resistor R11, and the other end of the thirteenth resistor R11 is electrically connected to the output end of the sampling circuit; the second input terminal of the comparator IC3A is also electrically connected to one end of a fourteenth resistor R9, and the other end of the fourteenth resistor R9 is electrically connected to the anode of the second diode D2, and the cathode of the second diode D2 is electrically connected to the output terminal of the comparator IC3A, and the output terminal of the comparator IC3A is also electrically connected to the input terminal of the logic control circuit.

[0063] Among them, Figure 5 As shown, the comparator IC3A is a rail-to-rail comparator. In the figure, the sampling voltage signal BJ and the reference signal Vref1 are compared with the voltage signal through the thirteenth resistor R11 and the twelfth resistor R12. When the sampling voltage signal BJ is less than the reference signal Vref1, the output is a low level (0-0.7V), and the module works normally. When the sampling voltage signal BJ is greater than the reference signal Vref1, the output is a high level, and the module is turned off. The fourteenth resistor R9 in the figure realizes negative logic feedback, and the second diode D2 is a unidirectional hysteresis diode. By adjusting the fourteenth resistor R9, the overcurrent point at which the module works normally again can be changed.

[0064] For further information, see Figure 6 As shown, the function of the logic control circuit is to control the on and off of the surge suppression circuit. The logic control circuit includes:

[0065] a second MOSFET tube Q3, wherein the source of the second MOSFET tube Q3 is electrically connected to the base of the second triode VT2, the drain of the second MOSFET tube Q3 is grounded, and the gate of the second MOSFET tube Q3 is electrically connected to the output end of the comparison circuit;

[0066] a third MOSFET tube Q4, wherein the source of the third MOSFET tube Q4 is electrically connected to one end of a fifteenth resistor R7, the other end of the fifteenth resistor R7 is electrically connected to the gate of the first MOSFET tube as an output end, the drain of the third MOSFET tube Q4 is grounded, and the gate of the third MOSFET tube Q4 is electrically connected to the gate of the second MOSFET tube Q3;

[0067] A fourth MOSFET tube Q5, a source of the fourth MOSFET tube Q5 is electrically connected to one end of a sixteenth resistor R8, the other end of the sixteenth resistor R8 is electrically connected to the emitter of the second triode VT2, a drain of the fourth MOSFET tube Q5 is grounded, and a gate of the fourth MOSFET tube Q5 is electrically connected to the gate of the second MOSFET tube Q3.

[0068] In normal operation, the sampling circuit converts the sampled output current signal into a voltage signal and compares it with the reference voltage. At this time, the output voltage signal is less than the reference voltage, the comparison circuit outputs a low level, and the surge suppression circuit works normally.

[0069] When overcurrent occurs, the sampling circuit converts the sampled output current signal into a voltage signal and compares it with the reference voltage. At this time, the output voltage signal is higher than the reference voltage, and the comparison circuit outputs a high level. The comparison circuit sends this signal to the logic control circuit. The second MOSFET tube Q3, the third MOSFET tube Q4, and the fourth MOSFET tube Q5 in the logic control circuit are all pulled down, the surge suppression circuit stops working, and the surge suppression circuit is restarted. If the surge suppression circuit is still in an overcurrent state, the above process is repeated to meet the design requirements of overcurrent protection. If the surge suppression circuit does not overcurrent after restarting, the surge suppression circuit works normally.

[0070] Furthermore, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6 and the fifth capacitor C2 have a plurality of different replacement specifications for adjusting the startup delay time of the system.

[0071] The system startup delay time can also be achieved through other methods, such as setting a timing circuit.

[0072] In the present invention, see Figure 5 As shown, the comparison circuit sends the LJKZ signal to the logic control circuit. When the logic control signal is at a low level (0-0.7V), the logic control circuit does not work. When the LJKZ signal is at a high level, the second MOSFET tube Q3, the third MOSFET tube Q4 and the fourth MOSFET tube Q5 are all pulled low, and the surge suppression circuit stops working.

[0073] Figure 6 The second MOSFET tube Q3 is connected to the base of the power supply part in the surge suppression circuit. The second MOSFET tube Q3 is turned on, so that the power supply transistor cannot output the power supply voltage until the LJKZ signal becomes a low-level signal, the second MOSFET tube Q3 is turned off, and the power supply transistor outputs the power supply voltage again. The power supply start-up delay time is determined by the fourth resistor R4, the fifth resistor R5, the sixth resistor R6 and the fifth capacitor C2. By adjusting 4, the fifth resistor R5, the sixth resistor R6 and the fifth capacitor C2, the re-working interval time of the surge suppression circuit can be changed.

[0074] Figure 6 The third MOSFET tube Q4 is used to pull down the gate signal of the second stage of the clamping main power MOSFET tube. When LJKZ is at a high level, VTH2 is quickly pulled down, turning off the main power MOSFET tube and stopping the surge suppression circuit from working.

[0075] Figure 6 The fourth MOSFET tube Q5 in the middle is used to pull down the VCC power supply, so that other surge suppression circuits also stop working.

[0076] The present invention provides a high-precision overcurrent short-circuit protection circuit, which can flexibly amplify the magnification and relatively freely scale the error, provide overcurrent protection of different currents for modules of different power levels, reduce the power consumption of overcurrent protection, and effectively reduce the power consumption of surge suppression circuits during continuous overcurrent and short circuit by adjusting the power-on delay time, thereby improving the reliability of the product, having strong practicality and being worthy of promotion.

[0077] What is disclosed above is only a preferred specific embodiment of the present invention; however, the embodiments of the present invention are not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A high-precision overcurrent short-circuit protection circuit, characterized in that: include: A surge suppression circuit is electrically connected between the external input terminal and the external output terminal; A bootstrap circuit, used for providing a driving voltage for the surge suppression circuit under normal working conditions, wherein an output end of the bootstrap circuit is electrically connected to a driving voltage of the surge suppression circuit; A sampling circuit, used for extracting an output current signal of an external output terminal and converting the current signal into a voltage signal, wherein an input terminal of the sampling circuit is electrically connected to the external output terminal; A comparison circuit, used for receiving a voltage signal sent by the sampling circuit, comparing the voltage signal with a reference voltage, and sending the comparison result to the logic control circuit, wherein the input end of the comparison circuit is electrically connected to the output end of the sampling circuit, and the output end of the comparison circuit is electrically connected to the input end of the logic control circuit; A logic control circuit, used for controlling the on and off of the surge suppression circuit, wherein the output end of the logic control circuit is electrically connected to the driving voltage of the surge suppression circuit, and is used for lowering the driving voltage of the surge suppression circuit in an overcurrent working state; The power supply circuit is electrically connected to the external input terminal, the bootstrap circuit, the sampling circuit, the comparison circuit and the logic control circuit respectively, and is used to ensure the normal power supply of the subsequent circuit; The surge suppression circuit comprises: At least two clamping units connected in parallel, the clamping units comprising: a first MOSFET tube, wherein a source electrode of the first MOSFET tube is electrically connected to the external output terminal, a drain electrode of the first MOSFET tube is electrically connected to the external input terminal, a gate electrode of the first MOSFET tube is electrically connected to one end of a first capacitor, the other end of the first capacitor is grounded, an end of the first capacitor away from the ground end is electrically connected to one end of a seventeenth resistor, and the other end of the seventeenth resistor is electrically connected to the source electrode of the first MOSFET tube; The external input terminal is electrically connected to one end of the second capacitor, and the other end of the second capacitor is grounded; the external output terminal is electrically connected to one end of the third capacitor, and the other end of the third capacitor is grounded; The power supply circuit comprises: A first power supply circuit is used to provide a stable voltage for the overcurrent protection circuit to ensure that the overcurrent protection circuit is continuously online. The first power supply circuit includes a first resistor with one end electrically connected to the external input terminal, the other end of the first resistor is electrically connected to the cathode of the first voltage regulator tube, and the anode of the first voltage regulator tube is grounded; the first power supply circuit also includes a second resistor with one end electrically connected to the external input terminal, the other end of the second resistor is electrically connected to the cathode of the first voltage regulator tube; the cathode of the first voltage regulator tube is electrically connected to the base of the first triode, the collector of the first triode is electrically connected to the external input terminal, the emitter of the first triode is electrically connected to one end of the fourth capacitor, and the other end of the fourth capacitor is grounded; the emitter of the first triode is also electrically connected to one end of the third resistor and the positive power supply interface of the operational amplifier, the other end of the third resistor is electrically connected to the first end of the integrated circuit, the integrated circuit is used to provide a reference voltage, the second end of the integrated circuit is electrically connected to the first input end of the comparison circuit, and the third end of the integrated circuit is grounded; The second power supply circuit is used to provide a stable voltage to the subsequent circuit to ensure the normal power supply of the subsequent circuit. The second power supply circuit includes a fourth resistor with one end electrically connected to the external input terminal, and the other end of the fourth resistor is electrically connected to one end of a fifth capacitor, and the other end of the fifth capacitor is grounded; the second power supply circuit also includes a fifth resistor with one end electrically connected to the external input terminal, and the other end of the fifth resistor is electrically connected to an end of the fifth capacitor away from the ground terminal; the second power supply circuit also includes a sixth resistor with one end electrically connected to the external input terminal, and the other end of the sixth resistor is electrically connected to an end of the fifth capacitor away from the ground terminal; a second transistor, the collector of the second transistor is connected to the external input terminal The second transistor is electrically connected to the anode of the first diode, the cathode of the first diode is electrically connected to the cathode of the second voltage regulator tube, and the anode of the second voltage regulator tube is grounded; the emitter of the second transistor is electrically connected to one end of the seventh capacitor and the positive power supply interface of the comparator, and the other end of the seventh capacitor is grounded; the base of the second transistor is also electrically connected to the first reference voltage interface end of the logic control circuit, and the emitter of the second transistor is electrically connected to the second reference voltage interface end of the logic control circuit.

2. A high-precision over-current short-circuit protection circuit according to claim 1, characterized in that: The sampling circuit comprises: An operational amplifier, a positive power supply interface of the operational amplifier is electrically connected to the emitter of the first transistor, and a negative power supply interface of the operational amplifier is grounded; a first input terminal of the operational amplifier is electrically connected to one end of a seventh resistor, and the other end of the seventh resistor is grounded; a second input terminal of the operational amplifier is electrically connected to one end of an eighth capacitor, and the other end of the eighth capacitor is grounded; the second input terminal of the operational amplifier is also electrically connected to one end of the eighth resistor, and the other end of the eighth resistor is grounded; the second input terminal of the operational amplifier is also electrically connected to one end of a ninth resistor, and the other end of the ninth resistor is electrically connected to one end of a tenth resistor, and the other end of the tenth resistor is grounded; an end of the tenth resistor away from the ground terminal is also electrically connected to one end of the ninth capacitor, and the other end of the ninth capacitor is electrically connected to an external output terminal; an end of the seventh resistor away from the ground terminal is electrically connected to one end of an eleventh resistor, and the other end of the eleventh resistor is electrically connected to the output terminal of the operational amplifier, an end of the seventh resistor away from the ground terminal is electrically connected to one end of the tenth capacitor, and the other end of the tenth capacitor is electrically connected to the output terminal of the operational amplifier, and the output terminal of the operational amplifier is electrically connected to the second input terminal of the comparison circuit.

3. A high-precision over-current short-circuit protection circuit according to claim 2, characterized in that: The comparison circuit comprises: A comparator, wherein the positive power supply interface of the comparator is electrically connected to the emitter of the second transistor, and the negative power supply interface of the comparator is grounded; the first input terminal of the comparator is electrically connected to one end of a twelfth resistor, and the other end of the twelfth resistor is electrically connected to the second end of the integrated circuit; the second input terminal of the comparator is electrically connected to one end of a thirteenth resistor, and the other end of the thirteenth resistor is electrically connected to the output end of the sampling circuit; the second input terminal of the comparator is also electrically connected to one end of a fourteenth resistor, and the other end of the fourteenth resistor is electrically connected to the anode of the second diode, the cathode of the second diode is electrically connected to the output terminal of the comparator, and the output terminal of the comparator is also electrically connected to the input terminal of the logic control circuit.

4. A high-precision over-current short-circuit protection circuit according to claim 1, characterized in that: The logic control circuit comprises: a second MOSFET tube, wherein the source of the second MOSFET tube is electrically connected to the base of the second triode, the drain of the second MOSFET tube is grounded, and the gate of the second MOSFET tube is electrically connected to the output end of the comparison circuit; a third MOSFET tube, wherein the source of the third MOSFET tube is electrically connected to one end of a fifteenth resistor, the other end of the fifteenth resistor is electrically connected to the gate of the first MOSFET tube as an output end, the drain of the third MOSFET tube is grounded, and the gate of the third MOSFET tube is electrically connected to the gate of the second MOSFET tube; A fourth MOSFET tube, a source of the fourth MOSFET tube is electrically connected to one end of a sixteenth resistor, the other end of the sixteenth resistor is electrically connected to the emitter of the second transistor, the drain of the fourth MOSFET tube is grounded, and the gate of the fourth MOSFET tube is electrically connected to the gate of the second MOSFET tube.

5. A high-precision over-current short-circuit protection circuit according to claim 1, characterized in that: The fourth resistor, the fifth resistor, the sixth resistor and the fifth capacitor have a plurality of different replacement specifications for adjusting the startup delay time of the system.

6. A high-precision over-current short-circuit protection circuit according to claim 1, characterized in that: The second power supply circuit is replaced by a timing circuit.

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