MOS power consumption self-locking protection circuit and method

Abstract

The application provides a MOS power consumption self-locking protection circuit and method in the technical field of linear power supply control, which comprises a differential pressure detection circuit, a differential pressure comparison circuit, an enabling circuit, a starting current comparison circuit, a maximum current comparison circuit, a reset circuit and an MCU; the input end of the differential pressure comparison circuit is connected with the output end of the differential pressure detection circuit, and the output end is connected with the enabling circuit; the input ends of the starting current comparison circuit and the maximum current comparison circuit are connected with the MCU, and the output ends are connected with the enabling circuit; the MCU is connected with the differential pressure detection circuit, the differential pressure comparison circuit and the enabling circuit respectively; the input end of the reset circuit is connected with the MCU, and the output end is connected with the starting current comparison circuit and the maximum current comparison circuit. The application has the advantages that the voltage difference and the current of the MOS are simultaneously dynamically controlled, and the service life of the MOS is greatly prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of linear power supply control, and particularly relates to a MOS tube power consumption self-locking protection circuit and method. BACKGROUND

[0002] At present, the MOS tube power consumption control in the linear power supply only controls the voltage difference at the two ends of the MOS tube, and the current flowing through the MOS tube is controlled by another control module, so that the voltage difference and the current are controlled separately, the overall control circuit and control logic are complex, and the voltage difference value and the current value are fixed values and cannot be adjusted, the hardware cannot be self-locked, and only the software can be self-locked, so that the overall power consumption control of the MOS tube is a punch type protection, and the MOS tube device is large in loss.

[0003] Therefore, how to provide a MOS tube power consumption self-locking protection circuit and method to simultaneously dynamically control the voltage difference and the current of the MOS tube and prolong the service life of the MOS tube has become a problem to be solved. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a MOS tube power consumption self-locking protection circuit and method to simultaneously dynamically control the voltage difference and the current of the MOS tube and prolong the service life of the MOS tube.

[0005] In a first aspect, the present application provides a MOS tube power consumption self-locking protection circuit, comprising a voltage difference detection circuit, a voltage difference comparison circuit, an enabling circuit, a control current comparison circuit, a maximum current comparison circuit, a reset circuit and an MCU.

[0006] The input end of the voltage difference comparison circuit is connected with the output end of the voltage difference detection circuit, and the output end is connected with the enabling circuit; the input ends of the control current comparison circuit and the maximum current comparison circuit are connected with the MCU, and the output ends are connected with the enabling circuit; the MCU is connected with the voltage difference detection circuit, the voltage difference comparison circuit and the enabling circuit respectively; the input end of the reset circuit is connected with the MCU, and the output end is connected with the control current comparison circuit and the maximum current comparison circuit.

[0007] Further, the voltage difference detection circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R7, a resistor R8 and an operational amplifier U1B.

[0008] The pin 5 of the operational amplifier U1B is connected with the resistor R2 and the resistor R7, the pin 6 is connected with the resistor R1 and the resistor R3, and the pin 7 is connected with the resistor R3, the resistor R8 and the voltage difference comparison circuit; the resistor R7 and the resistor R8 are grounded; and the resistor R2 is connected with the MCU.

[0009] Further, the differential pressure comparison circuit comprises a resistor R4, a resistor R5, a resistor R5, a capacitor C1 and an operational amplifier U1A;

[0010] Pin 1 of the operational amplifier U1A is connected with the resistor R6 and the enable circuit, pin 2 is connected with the resistor R4, pin 3 is connected with the resistor R5 and the capacitor C1; the resistor R5 is connected with the differential pressure detection circuit; the resistor R4 is connected with the MCU; the resistor R6 and the capacitor C1 are grounded.

[0011] Further, the enable circuit comprises a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C2, an optocoupler U4 and a MOS tube Q1;

[0012] Pin 1 of the optocoupler U4 is connected with the resistor R11 and the resistor R12, pin 2 is connected with the resistor R12 and grounded, pin 3 is connected with the differential pressure comparison circuit, pin 4 is connected with the resistor R13 and the maximum current comparison circuit; the resistor R11 is connected with the control current comparison circuit; the gate of the MOS tube Q1 is connected with the resistor R13, the resistor R14 and the capacitor C2, the source is connected with the resistor R14 and the capacitor C2 and grounded.

[0013] Further, the control current comparison circuit comprises a resistor R15, a resistor R16, a resistor R20, a resistor R24, a diode D2, a light emitting diode LED2 and an operational amplifier U3;

[0014] Pin 1 of the operational amplifier U3 is connected with the input end of the diode D2 and the input end of the light emitting diode LED2, pin 3 is connected with the resistor R24, pin 4 is connected with the resistor R15; the resistor R15 is connected with the MCU; one end of the resistor R20 is connected with the resistor 16, the resistor R24 and the reset circuit, the other end is connected with the output end of the diode D2; the output end of the light emitting diode LED2 is connected with the enable circuit.

[0015] Further, the maximum current comparison circuit comprises a resistor R9, a resistor R10, a resistor R19, a resistor R23, a diode D1, a light emitting diode LED1 and an operational amplifier U2;

[0016] Pin 1 of the operational amplifier U2 is connected with the input end of the diode D1 and the input end of the light emitting diode LED1, pin 3 is connected with the resistor R23, pin 4 is connected with the resistor R9; the resistor R9 is connected with the MCU; one end of the resistor R19 is connected with the resistor 10, the resistor R23 and the reset circuit, the other end is connected with the output end of the diode D1; the output end of the light emitting diode LED1 is connected with the enable circuit.

[0017] Further, the reset circuit comprises a resistor R17, a resistor R18, a resistor R21, a resistor R22, a MOS tube Q2 and a MOS tube Q3;

[0018] The drain of the MOS tube Q2 is connected with the control current comparison circuit, the source is connected with the resistor R18 and grounded, and the gate is connected with the resistor R17 and the resistor R18; the resistor R17 is connected with the MCU;

[0019] The drain of the MOS tube Q3 is connected with the maximum current comparison circuit, the source is connected with the resistor R22 and grounded, and the gate is connected with the resistor R21 and the resistor R22; the resistor R21 is connected with the MCU.

[0020] In the second aspect, the application provides a MOS tube power consumption self-locking protection method, comprising the following steps:

[0021] In step S10, the resistor R1 of the differential pressure detection circuit is connected with the voltage sampling point of the linear power supply to obtain an output voltage value FB_VOUT; the resistor R16 of the control current comparison circuit and the resistor R10 of the maximum current comparison circuit are connected with the current sampling point of the linear power supply to obtain an output current value FB_IOUT; the drain of the MOS tube Q1 of the enabling circuit is connected with the control end of the linear power supply;

[0022] In step S20, the differential pressure detection circuit obtains the front-end voltage value VF_MOS of the MOS tube of the linear power supply from the MCU through the resistor R2, and calculates the voltage difference FV_DEF between the FB_VOUT and VF_MOS and inputs the voltage difference into the differential pressure comparison circuit;

[0023] In step S30, the differential pressure comparison circuit judges whether the FV_DEF is greater than the protection differential pressure control value VPRO_SET set by the MCU, if yes, outputs a high-level signal CONB to the pin 3 of the optocoupler U4 of the enabling circuit; if not, outputs a low-level signal CONB to the pin 3 of the optocoupler U4 of the enabling circuit;

[0024] In step S40, the control current comparison circuit judges whether the FB_IOUT is greater than the control current control value IPRO_SET_MIN set by the MCU, if yes, outputs a high-level signal CONA to the resistor R11 of the enabling circuit; if not, outputs a low-level signal CONA to the resistor R11 of the enabling circuit;

[0025] In step S50, the maximum current comparison circuit judges whether the FB_IOUT is greater than the maximum current control value IPRO_SET_MAX set by the MCU, if yes, outputs a high-level signal CONBB to the resistor R13 of the enabling circuit; if not, outputs a low-level signal CONBB to the resistor R13 of the enabling circuit.

[0026] Step S60, when the signal CONB and the signal CONA are both high level, or the signal CONBB is high level, the drain of the MOS Q1 outputs the low level signal PRO_AB, and then the output of the linear power supply is turned off, and the self-locking protection state is entered.

[0027] Step S70, after troubleshooting, the MCU enables the drain of the MOS Q1 to output the high level signal PRO_AB through the reset circuit, and then the output of the linear power supply is restored.

[0028] The present application has the advantages of:

[0029] By setting the differential pressure detection circuit and the differential pressure comparison circuit, the differential pressure detection circuit outputs the voltage difference FV_DEF to the differential pressure comparison circuit, and the differential pressure comparison circuit outputs the signal CONB to the enable circuit by comparing the voltage difference FV_DEF with the protection voltage difference control value VPRO_SET set by the MCU; the start-up current comparison circuit is set to compare the output current value FB_IOUT with the start-up current control value IPRO_SET_MIN set by the MCU to output the signal CONA to the enable circuit; the maximum current comparison circuit is set to compare the output current value FB_IOUT with the maximum current control value IPRO_SET_MAX set by the MCU to output the signal CONBB to the enable circuit; when the signal CONB and the signal CONA are both high level, the pin 4 of the optocoupler U4 outputs high level, and then the drain of the MOS Q1 of the enable circuit outputs the low level signal PRO_AB to turn off the output of the linear power supply; when the signal CONB is low level and cannot drive the pin 4 of the optocoupler U4 to output high level, as long as the signal CONBB is high level, the drain of the MOS Q1 of the enable circuit outputs the low level signal PRO_AB to turn off the output of the linear power supply; the protection voltage difference control value VPRO_SET, the start-up current control value IPRO_SET_MIN, and the maximum current control value IPRO_SET_MAX can be set by the MCU as needed, that is, the voltage difference and the current are controlled at the same time, the values of the controlled voltage difference and the current can be set as needed, as long as the voltage difference or the current exceeds the control value, the output of the linear power supply is turned off, the self-locking protection state is entered, the MOS tube is prevented from being damaged, and the voltage difference and the current of the MOS tube are dynamically controlled at the same time, which greatly prolongs the service life of the MOS tube. BRIEF DESCRIPTION OF DRAWINGS

[0030] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0031] Figure 1 It is a circuit principle block diagram of a MOS tube power consumption self-locking protection circuit.

[0032] Figure 2 is a circuit diagram of the differential voltage detection circuit of the application.

[0033] Figure 3 is a circuit diagram of the differential voltage comparison circuit of the application.

[0034] Figure 4 is a circuit diagram of the enable circuit of the application.

[0035] Figure 5 is a circuit diagram of the start control current comparison circuit of the application.

[0036] Figure 6 is a circuit diagram of the maximum current comparison circuit of the application.

[0037] Figure 7 is a circuit diagram of the reset circuit of the application.

[0038] Figure 8 is a circuit diagram of the MCU of the application.

[0039] Figure 9 is a flow chart of the MOS tube power consumption self-locking protection method of the application. DETAILED DESCRIPTION

[0040] The technical solution in the embodiments of the application has the following general idea: the differential voltage detection circuit and the differential voltage comparison circuit are arranged to monitor the voltage difference and output a signal CONB to the enable circuit; the start control current comparison circuit and the maximum current comparison circuit are arranged to monitor the current and output a signal CONA and a signal CONBB to the enable circuit, respectively; the enable circuit can control the level of the drain output of the MOS tube Q1 based on the input signals CONB, CONA and CONBB, and turn off the output of the linear power supply when the output is a low level; the protection differential voltage control value VPRO_SET, the start control current control value IPRO_SET_MIN and the maximum current control value IPRO_SET_MAX compared by the differential voltage comparison circuit, the start control current comparison circuit and the maximum current comparison circuit can be set by the MCU as required, and the compatibility is strong, so that the voltage difference and the current of the MOS tube are dynamically controlled at the same time, and the service life of the MOS tube is prolonged.

[0041] Referring to Figures 1 to 9 , a preferred embodiment of the MOS tube power consumption self-locking protection circuit of the application includes a differential voltage detection circuit, a differential voltage comparison circuit, an enable circuit, a start control current comparison circuit, a maximum current comparison circuit, a reset circuit and a MCU.

[0042] The differential pressure detection circuit is used for comparing the output voltage value FB_VOUT of the linear power supply with the front end voltage value VF_MOS of the linear power supply MOS tube, and outputting a voltage difference FV_DEF to the differential pressure comparison circuit; the differential pressure comparison circuit is used for comparing the voltage difference FV_DEF with a protection differential pressure control value VPRO_SET set by the MCU, and outputting a signal CONB to the enable circuit; the starting current comparison circuit is used for comparing the output current value FB_IOUT of the linear power supply with a starting current control value IPRO_SET_MIN set by the MCU, and outputting a signal CONA to the enable circuit; the maximum current comparison circuit is used for comparing the output current value FB_IOUT of the linear power supply with a maximum current control value IPRO_SET_MAX set by the MCU, and outputting a signal CONBB to the enable circuit; the enable circuit is used for outputting a high level or a low level based on the received signals CONA, CONB and CONBB, and shutting off the output of the linear power supply when a low level is outputted; the reset circuit is used for receiving a control signal of the MCU to control the starting current comparison circuit and the maximum current comparison circuit to output a low level, so that the enable circuit outputs a high level and the output of the linear power supply is restored; and the MCU is used for controlling the operation of the self-locking protection circuit, in a specific implementation, as long as an MCU capable of realizing this function is selected from the prior art, and the control program is well known to those skilled in the art, which can be obtained without creative labor.

[0043] The input end of the differential pressure comparison circuit is connected with the output end of the differential pressure detection circuit, and the output end is connected with the enable circuit; the input ends of the starting current comparison circuit and the maximum current comparison circuit are connected with the MCU, and the output ends are connected with the enable circuit; the MCU is connected with the differential pressure detection circuit, the differential pressure comparison circuit and the enable circuit respectively; and the input end of the reset circuit is connected with the MCU, and the output end is connected with the starting current comparison circuit and the maximum current comparison circuit.

[0044] The differential pressure detection circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R7, a resistor R8 and an operational amplifier U1B; and the model of the operational amplifier U1B is preferably ADA4522-2.

[0045] Pin 5 of the operational amplifier U1B is connected with the resistor R2 and the resistor R7, pin 6 is connected with the resistor R1 and the resistor R3, and pin 7 is connected with the resistor R3, the resistor R8 and the resistor R5 of the differential pressure comparison circuit; the resistor R7 and the resistor R8 are grounded; the resistor R2 is connected with the MCU; and the resistor R1 is connected with the voltage sampling point of the linear power supply.

[0046] The differential pressure comparison circuit comprises a resistor R4, a resistor R5, a resistor R5, a capacitor C1 and an operational amplifier U1A; the model of the operational amplifier U1A is preferably ADA4522-2;

[0047] Pin 1 of the operational amplifier U1A is connected with a resistor R6 and pin 3 of the optocoupler U4 of the enable circuit, pin 2 is connected with the resistor R4, and pin 3 is connected with the resistor R5 and the capacitor C1; the resistor R5 is connected with pin 7 of the operational amplifier U1B of the differential pressure detection circuit; the resistor R4 is connected with the MCU; the resistor R6 and the capacitor C1 are grounded.

[0048] The enable circuit comprises a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C2, an optocoupler U4 and a MOS tube Q1; the model of the optocoupler U4 is preferably AQY212S; the model of the MOS tube Q1 is preferably NCE2312;

[0049] Pin 1 of the optocoupler U4 is connected with the resistor R11 and the resistor R12, pin 2 is connected with the resistor R12 and grounded, pin 3 is connected with pin 1 of the operational amplifier U1A of the differential pressure comparison circuit, and pin 4 is connected with the resistor R13 and the output end of the light-emitting diode LED1 of the maximum current comparison circuit; the resistor R11 is connected with the output end of the light-emitting diode LED2 of the control current comparison circuit; the gate of the MOS tube Q1 is connected with the resistor R13, the resistor R14 and the capacitor C2, the source is connected with the resistor R14 and the capacitor C2 and grounded, and the drain is connected with the control end of the linear power supply.

[0050] The control current comparison circuit comprises a resistor R15, a resistor R16, a resistor R20, a resistor R24, a diode D2, a light-emitting diode LED2 and an operational amplifier U3; the model of the operational amplifier U3 is preferably OPA188;

[0051] Pin 1 of the operational amplifier U3 is connected with the input end of the diode D2 and the input end of the light-emitting diode LED2, pin 3 is connected with the resistor R24, and pin 4 is connected with the resistor R15; the resistor R15 is connected with the MCU; one end of the resistor R20 is connected with the resistor 16, the resistor R24 and the reset circuit, and the other end is connected with the output end of the diode D2; the output end of the light-emitting diode LED2 is connected with the resistor R11 of the enable circuit; the resistor R16 is connected with the current sampling point of the linear power supply.

[0052] The maximum current comparison circuit comprises a resistor R9, a resistor R10, a resistor R19, a resistor R23, a diode D1, a light emitting diode LED1 and an operational amplifier U2; the model of the operational amplifier U2 is preferably OPA188;

[0053] Pin 1 of the operational amplifier U2 is connected with the input end of the diode D1 and the input end of the light emitting diode LED1, pin 3 is connected with the resistor R23, and pin 4 is connected with the resistor R9; the resistor R9 is connected with the MCU; one end of the resistor R19 is connected with the resistor 10, the resistor R23 and the reset circuit, and the other end is connected with the output end of the diode D1; the output end of the light emitting diode LED1 is connected with pin 4 of the optocoupler U4 of the enable circuit; the resistor R10 is connected with the current sampling point of the linear power supply.

[0054] The reset circuit comprises a resistor R17, a resistor R18, a resistor R21, a resistor R22, a MOS tube Q2 and a MOS tube Q3; the models of the MOS tube Q2 and the MOS tube Q3 are preferably NCE2312;

[0055] The drain of the MOS tube Q2 is connected with the resistor R16, the resistor R20 and the resistor R24 of the control current comparison circuit, the source is connected with the resistor R18 and grounded, and the gate is connected with the resistor R17 and the resistor R18; the resistor R17 is connected with the MCU;

[0056] The drain of the MOS tube Q3 is connected with the resistor R10, the resistor R19 and the resistor R23 of the maximum current comparison circuit, the source is connected with the resistor R22 and grounded, and the gate is connected with the resistor R21 and the resistor R22; the resistor R21 is connected with the MCU.

[0057] The preferred embodiment of the MOS tube power consumption self-locking protection method comprises the following steps:

[0058] In step S10, the resistor R1 of the differential pressure detection circuit is connected with the voltage sampling point of the linear power supply to obtain an output voltage value FB_VOUT; the resistor R16 of the control current comparison circuit and the resistor R10 of the maximum current comparison circuit are connected with the current sampling point of the linear power supply to obtain an output current value FB_IOUT; the drain of the MOS tube Q1 of the enable circuit is connected with the control end of the linear power supply;

[0059] In step S20, the differential pressure detection circuit obtains the front-end voltage value VF_MOS of the MOS tube of the linear power supply from the MCU through the resistor R2, and calculates the voltage difference FV_DEF between the FB_VOUT and VF_MOS and inputs the voltage difference into the differential pressure comparison circuit;

[0060] Step S30, the differential pressure comparison circuit judges whether the FV_DEF is greater than the protection differential pressure control value VPRO_SET set by the MCU, if yes, the high level signal CONB is output to the pin 3 of the optocoupler U4 of the enable circuit, if not, the low level signal CONB is output to the pin 3 of the optocoupler U4 of the enable circuit;

[0061] Step S40, the starting current comparison circuit judges whether the FB_IOUT is greater than the starting current control value IPRO_SET_MIN set by the MCU, if yes, the high level signal CONA is output to the resistance R11 of the enable circuit, if not, the low level signal CONA is output to the resistance R11 of the enable circuit;

[0062] Step S50, the maximum current comparison circuit judges whether the FB_IOUT is greater than the maximum current control value IPRO_SET_MAX set by the MCU, if yes, the high level signal CONBB is output to the resistance R13 of the enable circuit, if not, the low level signal CONBB is output to the resistance R13 of the enable circuit;

[0063] Step S60, when the signal CONB and the signal CONA are both high level, or the signal CONBB is high level, the low level signal PRO_AB is output to the drain of the MOS Q1, and then the output of the linear power supply is turned off, and the self-locking protection state is entered;

[0064] That is, when the signal CONB and the signal CONA are both high level, it is indicated that the FV_DEF is greater than the VPRO_SET, the FB_IOUT is greater than the IPRO_SET_MIN, the over-protection differential current and over-protection current mode is started, and the MOS Q1 is driven to output the low level to turn off the output of the linear power supply, when the FV_DEF is less than the VPRO_SET, but the FB_IOUT is greater than the IPRO_SET_MAX, the maximum current protection mode is started, and the MOS Q1 is driven to output the low level to turn off the output of the linear power supply;

[0065] Step S70, after troubleshooting, the MCU enables the high level signal PRO_AB output to the drain of the MOS Q1 through the reset circuit, and then the output of the linear power supply is restored;

[0066] When being in the over-protection differential current and over-protection current mode, the MCU controls the starting current comparison circuit to output the low level through the MOS Q2, and then the high level signal PRO_AB output to the drain of the MOS Q1 is enabled, when being in the maximum current protection mode, the MCU controls the maximum current comparison circuit to output the low level through the MOS Q3, and then the high level signal PRO_AB output to the drain of the MOS Q1 is enabled.

[0067] In summary, the advantages of the application are:

[0068] By setting the differential pressure detection circuit and the differential pressure comparison circuit, the differential pressure detection circuit outputs the voltage difference FV_DEF to the differential pressure comparison circuit, the differential pressure comparison circuit outputs the signal CONB to the enable circuit by comparing the voltage difference FV_DEF with the protection voltage difference control value VPRO_SET set by the MCU; the start-up current comparison circuit outputs the signal CONA to the enable circuit by comparing the output current value FB_IOUT with the start-up current control value IPRO_SET_MIN set by the MCU; the maximum current comparison circuit outputs the signal CONBB to the enable circuit by comparing the output current value FB_IOUT with the maximum current control value IPRO_SET_MAX set by the MCU; when the signal CONB and the signal CONA are both high, the pin 4 of the optocoupler U4 outputs a high level, and then the drain of the MOS tube Q1 of the enable circuit outputs a low level signal PRO_AB to shut down the output of the linear power supply; when the signal CONB is low and cannot drive the pin 4 of the optocoupler U4 to output a high level, as long as the signal CONBB is high, the drain of the MOS tube Q1 of the enable circuit outputs a low level signal PRO_AB to shut down the output of the linear power supply; the protection voltage difference control value VPRO_SET, the start-up current control value IPRO_SET_MIN and the maximum current control value IPRO_SET_MAX can be set by the MCU as needed, that is, the voltage difference and the current are controlled at the same time, the values of the controlled voltage difference and the current can be set as needed, as long as the voltage difference or the current exceeds the control value, the output of the linear power supply is shut down, the self-locking protection state is entered, the MOS tube is prevented from being damaged, and finally the voltage difference and the current of the MOS tube are dynamically controlled at the same time, the service life of the MOS tube is greatly prolonged.

[0069] Although the specific embodiments of the present application are described above, those skilled in the art should understand that the specific embodiments described are only illustrative, and are not intended to limit the scope of the present application, and equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present application should be covered within the scope of the claims of the present application.

Claims

1. A MOSFET power consumption self-locking protection circuit, characterized in that: The differential pressure detection circuit, the differential pressure comparison circuit, the enable circuit, the control current comparison circuit, the maximum current comparison circuit, the reset circuit and the MCU are connected in series. The input end of the differential pressure comparison circuit is connected with the output end of the differential pressure detection circuit, and the output end is connected with the enable circuit; the input ends of the control current comparison circuit and the maximum current comparison circuit are connected with the MCU, and the output ends are connected with the enable circuit; the MCU is connected with the differential pressure detection circuit, the differential pressure comparison circuit and the enable circuit respectively; the input end of the reset circuit is connected with the MCU, and the output end is connected with the control current comparison circuit and the maximum current comparison circuit. The differential pressure detection circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R7, a resistor R8 and an operational amplifier U1B. The pin 5 of the operational amplifier U1B is connected with the resistor R2 and the resistor R7, the pin 6 is connected with the resistor R1 and the resistor R3, and the pin 7 is connected with the resistor R3, the resistor R8 and the differential pressure comparison circuit; the resistor R7 and the resistor R8 are grounded; and the resistor R2 is connected with the MCU. The differential pressure comparison circuit comprises a resistor R4, a resistor R5, a resistor R6, a capacitor C1 and an operational amplifier U1A. The pin 1 of the operational amplifier U1A is connected with the resistor R6 and the enable circuit, the pin 2 is connected with the resistor R4, and the pin 3 is connected with the resistor R5 and the capacitor C1; the resistor R5 is connected with the differential pressure detection circuit; the resistor R4 is connected with the MCU; and the resistor R6 and the capacitor C1 are grounded. The enable circuit comprises a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C2, an optical coupler U4 and a MOS tube Q1. The pin 1 of the optical coupler U4 is connected with the resistor R11 and the resistor R12, the pin 2 is connected with the resistor R12 and grounded, the pin 3 is connected with the differential pressure comparison circuit, and the pin 4 is connected with the resistor R13 and the maximum current comparison circuit; the resistor R11 is connected with the control current comparison circuit; the gate of the MOS tube Q1 is connected with the resistor R13, the resistor R14 and the capacitor C2, and the source is connected with the resistor R14 and the capacitor C2 and grounded. The control current comparison circuit comprises a resistor R15, a resistor R16, a resistor R20, a resistor R24, a diode D2, a light emitting diode LED2 and an operational amplifier U3. The pin 1 of the operational amplifier U3 is connected with the input end of the diode D2 and the input end of the light emitting diode LED2, the pin 3 is connected with the resistor R24, and the pin 4 is connected with the resistor R15; the resistor R15 is connected with the MCU; one end of the resistor R20 is connected with the resistor R16, the resistor R24 and the reset circuit, and the other end is connected with the output end of the diode D2; and the output end of the light emitting diode LED2 is connected with the enable circuit.

2. The MOS power self-lock protection circuit according to claim 1, wherein: The maximum current comparison circuit comprises a resistor R9, a resistor R10, a resistor R19, a resistor R23, a diode D1, a light emitting diode LED1 and an operational amplifier U2. Pin 1 of the operational amplifier U2 is connected with the input end of diode D1 and the input end of light emitting diode LED1, pin 3 is connected with resistor R23, and pin 4 is connected with resistor R9; the resistor R9 is connected with MCU; one end of resistor R19 is connected with resistor R10, resistor R23 and reset circuit, and the other end is connected with the output end of diode D1; the output end of light emitting diode LED1 is connected with enable circuit.

3. The MOS power self-lock protection circuit according to claim 1, wherein: The reset circuit comprises resistor R17, resistor R18, resistor R21, resistor R22, MOS tube Q2 and MOS tube Q3; The drain of MOS tube Q2 is connected with control current comparison circuit, the source is connected with resistor R18 and grounded, and the gate is connected with resistor R17 and resistor R18; the resistor R17 is connected with MCU; The drain of MOS tube Q3 is connected with maximum current comparison circuit, the source is connected with resistor R22 and grounded, and the gate is connected with resistor R21 and resistor R22; the resistor R21 is connected with MCU.

4. A MOS power self-locking protection method, characterized in that: The method needs to use the self-locking protection circuit as claimed in any one of claims 1 to 3, comprising the following steps: In step S10, the resistor R1 of the differential pressure detection circuit is connected with the voltage sampling point of the linear power supply to obtain the output voltage value FB_VOUT; the resistor R16 of the control current comparison circuit and the resistor R10 of the maximum current comparison circuit are connected with the current sampling point of the linear power supply to obtain the output current value FB_IOUT; the drain of MOS tube Q1 of the enable circuit is connected with the control end of the linear power supply; In step S20, the differential pressure detection circuit obtains the front end voltage value VF_MOS of the MOS tube of the linear power supply from MCU through resistor R2, and calculates the voltage difference FV_DEF between FB_VOUT and VF_MOS and inputs the voltage difference into the differential pressure comparison circuit; In step S30, the differential pressure comparison circuit judges whether FV_DEF is greater than the protection differential pressure control value VPRO_SET set by MCU, if yes, outputs the high level signal CONB to pin 3 of optocoupler U4 of the enable circuit; if not, outputs the low level signal CONB to pin 3 of optocoupler U4 of the enable circuit; In step S40, the control current comparison circuit judges whether FB_IOUT is greater than the control current control value IPRO_SET_MIN set by MCU, if yes, outputs the high level signal CONA to resistor R11 of the enable circuit; if not, outputs the low level signal CONA to resistor R11 of the enable circuit; In step S50, the maximum current comparison circuit judges whether FB_IOUT is greater than the maximum current control value IPRO_SET_MAX set by MCU, if yes, outputs the high level signal CONBB to resistor R13 of the enable circuit; if not, outputs the low level signal CONBB to resistor R13 of the enable circuit; Step S60, when the signal CONB and the signal CONA are both high level, or the signal CONBB is high level, the drain of the MOS Q1 outputs the low level signal PRO_AB, and then the output of the linear power supply is turned off, and the self-locking protection state is entered; Step S70, after troubleshooting, the MCU enables the drain of the MOS Q1 to output the high level signal PRO_AB through the reset circuit, and then the output of the linear power supply is restored.

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