Protection circuit with adjustable over-current value of controller

Abstract

The invention discloses a protection circuit with an adjustable over-current value of a controller. A power supply supplies power to a load RL through a resistor R4 and an MOS tube Q1 in sequence, two input ends of a current detector U1 are connected with two ends of the resistor R4, an output end of the current detector U1 is connected with a triode Q36 through a diode D1, the triode Q36 is connected with a triode Q37, one end of the triode Q36 is grounded, and the output end of the current detector U1 is grounded through a resistor R3; the power supply is connected with the MOS tube Q1 through the resistor R1, the power supply is connected with the triode Q37 through the resistor R2, the triode Q37 is connected with the MOS tube Q1, and one end of the triode Q37 is grounded. The over-current threshold value is adjusted by monitoring the current in the loop in real time and adjusting the resistance value, power supply is cut off when the loop current exceeds the over-current threshold value, power supply is automatically normal when an over-current fault is revoked, and the safety level of the vehicle-mounted controller in use is improved through the circuit design.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive electronic circuits, and in particular to a protection circuit with an adjustable controller overcurrent value. Background Art

[0002] Typically, in-vehicle controllers use fuses as overcurrent protection devices for the controller's power supply lines. Fuses can be divided into single-break and resettable types. Resettable fuses are typically used within controllers for overcurrent protection. Resettable fuses utilize the thermal effects of overcurrent to cause changes in their internal structure, increasing their resistance and thus achieving current limiting.

[0003] Using resettable fuses as overcurrent protection devices on power lines presents the following major issues: 1. Because the resistance of resettable fuses is affected by temperature, the overcurrent threshold at room temperature differs significantly from that at high temperatures, making it impossible to guarantee the required accuracy of the overcurrent threshold across the entire temperature range. 2. Adjusting the overcurrent threshold requires changing the fuse model. Typically, the larger the current, the larger the fuse size. This can lead to physical interference and other issues in certain designs, resulting in poor scalability. Summary of the Invention

[0004] In order to solve the problems existing in the background technology, the present invention provides a protection circuit with an adjustable controller overcurrent value.

[0005] The technical solution adopted in the present invention is:

[0006] The present invention comprises an overcurrent detection part and an overcurrent protection switch part which are connected to each other, wherein the overcurrent detection part is connected to the load RL via the overcurrent protection switch part;

[0007] The overcurrent detection part includes a resistor R3, a resistor R4, a current detector U1, a diode D1 and a transistor Q36, the power supply VBAT is connected to the overcurrent protection switch part via the resistor R4, the two input ends of the current detector U1 are respectively connected to the two ends of the resistor R4, the output end of the current detector U1 is connected to the transistor Q36 via the diode D1, the transistor Q36 is connected to the overcurrent protection switch part, the transistor Q36 is grounded, and the output end of the current detector U1 is grounded via the resistor R3;

[0008] The overcurrent protection switch part includes a resistor R1, a resistor R2, a transistor Q37 and a MOS transistor Q1. The power supply VBAT is connected to the MOS transistor Q1 via the resistor R4. The MOS transistor Q1 is grounded via the load RL. The power supply VBAT is connected to the MOS transistor Q1 via the resistor R1. The power supply VBAT is connected to the transistor Q37 via the resistor R2. The transistor Q37 is connected to the MOS transistor Q1. The transistor Q37 is grounded. The transistor Q36 is connected to the transistor Q37.

[0009] The non-inverting input terminal of the current detector U1 is connected to one end of the resistor R4 connected to the power supply VBAT, the inverting input terminal of the current detector U1 is connected to the other end of the resistor R4, the ground terminal of the current detector U1 is grounded, the output terminal of the current detector U1 is connected to the base terminal of the transistor Q36 via the diode D1, the collector terminal of the transistor Q36 is connected to the overcurrent protection switch part, and the emitter terminal of the transistor Q36 is grounded.

[0010] The power supply VBAT is connected to the source terminal of the MOS transistor Q1 via the resistor R4, the drain terminal of the MOS transistor Q1 is grounded via the load RL, the power supply VBAT is connected to the gate terminal of the MOS transistor Q1 via the resistor R1, the power supply VBAT is connected to the base terminal of the transistor Q37 via the resistor R2, the collector terminal of the transistor Q37 is connected to the gate terminal of the MOS transistor Q1, the emitter terminal of the transistor Q37 is grounded, and the collector terminal of the transistor Q36 is connected to the base terminal of the transistor Q37.

[0011] The anode of the diode D1 is connected to the output terminal of the current detector U1 , and the cathode is connected to the base terminal of the transistor Q36 .

[0012] The MOS transistor Q1 is a PMOS transistor, and the transistor Q36 and the transistor Q37 are both NPN transistors.

[0013] The protection circuit is applied to a vehicle-mounted controller, the power supply VBAT is connected to a vehicle-mounted battery using a vehicle-mounted wiring harness, and the load RL is an internal load of the controller.

[0014] The protection circuit includes a normal mode and a cyclic protection mode. When the current flowing through the resistor R4 is less than the overcurrent threshold value, the protection circuit operates in the normal mode; when the current flowing through the resistor R4 is greater than or equal to the overcurrent threshold value, the protection circuit operates in the cyclic protection mode.

[0015] The normal mode is specifically:

[0016] When the current flowing through the resistor R4 is less than the overcurrent threshold, the difference between the two input terminals of the current detector U1 is the voltage drop of the resistor R4, and the voltage at the output terminal of the current detector U1 is less than the sum of the conduction voltage drop of the diode D1 and the turn-on voltage of the transistor Q36. At this time, the voltage difference V between the base terminal and the emitter terminal of the transistor Q36 is BE is less than the turn-on voltage of transistor Q36, transistor Q36 is not conducting, and the voltage difference V between the base terminal and the emitter terminal of transistor Q37 is BE The transistor Q37 is turned on, the gate terminal of the MOS tube Q1 is grounded, and the source terminal voltage of the MOS tube Q1 is the voltage of the power supply VBAT after the voltage drop of the resistor R4. The voltage difference between the gate terminal and the source terminal of the MOS tube Q1 is Vgs is less than the threshold voltage of the MOS tube Q1, the MOS tube Q1 is turned on, and the power supply VBAT supplies power to the load RL through the resistor R4 and the MOS tube Q1.

[0017] The cyclic protection mode includes a protection mode and a self-recovery mode, and the cyclic protection mode works in sequence according to the protection mode and the self-recovery mode;

[0018] The protection mode is specifically:

[0019] When the current flowing through the resistor R4 is greater than or equal to the overcurrent threshold, the difference between the two input terminals of the current detector U1 is the voltage drop of the resistor R4, and the voltage at the output terminal of the current detector U1 is greater than or equal to the sum of the conduction voltage drop of the diode D1 and the turn-on voltage of the transistor Q36. At this time, the voltage difference V between the base terminal and the emitter terminal of the transistor Q36 is BE If the voltage is greater than or equal to the turn-on voltage of transistor Q36, transistor Q36 is turned on, and the base of transistor Q37 is grounded through transistor Q36, thereby making the voltage difference V between the base terminal and the emitter terminal of transistor Q37 BE If the voltage is less than the turn-on voltage of transistor Q37, transistor Q37 will not conduct. The gate terminal voltage of MOS tube Q1 is pulled up to the power supply VBAT by resistor R1. The voltage difference V between the gate terminal and the source terminal of MOS tube Q1 is gs If the voltage is greater than or equal to the threshold voltage of the MOS tube Q1, the MOS tube Q1 is not turned on, and the power supply VBAT cannot supply power to the load RL through the resistor R4 and the MOS tube Q1;

[0020] The self-recovery mode is specifically:

[0021] After the protection circuit works in protection mode, no current flows through the resistor R4, and the output voltage of the current detector U1 is 0 volts, so that the voltage difference V between the base terminal and the emitter terminal of the transistor Q36 is BE is less than the turn-on voltage of transistor Q36, transistor Q36 is not turned on, making the voltage difference V between the base terminal and the emitter terminal of transistor Q37 BE The transistor Q37 is turned on, the gate terminal of the MOS tube Q1 is grounded, and the source terminal voltage of the MOS tube Q1 is the voltage of the power supply VBAT after the voltage drop of the resistor R4. The voltage difference between the gate terminal and the source terminal of the MOS tube Q1 is V gs When the voltage is lower than the threshold voltage of MOS tube Q1, MOS tube Q1 is turned on, and then current flows through resistor R4;

[0022] Then judge the current flowing through resistor R4:

[0023] When the current flowing through resistor R4 is less than the overcurrent threshold, the protection circuit operates in normal mode;

[0024] When the current flowing through the resistor R4 is greater than or equal to the overcurrent threshold, the protection circuit returns to the protection mode and operates in the protection mode.

[0025] The protection circuit sets the overcurrent threshold value by adjusting the resistance of the resistor R4.

[0026] Beneficial effects of the present invention:

[0027] This invention monitors the current in the circuit in real time and disconnects power when the circuit current exceeds the overcurrent threshold. Power is automatically restored when the overcurrent fault is resolved. The overcurrent threshold is accurate across the entire temperature range. The overcurrent threshold can be adjusted by adjusting the resistor value to meet the protection requirements of different overcurrent scenarios. This circuit design improves the safety level of vehicle controllers. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of a protection circuit with an adjustable overcurrent value for the controller. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] like Figure 1 As shown, the specific circuit includes an overcurrent detection part (M1) and an overcurrent protection switch part (M2) connected to each other, and the overcurrent detection part (M1) is connected to the load RL through the overcurrent protection switch part (M2);

[0031] The overcurrent detection portion (M1) includes a resistor R3, a resistor R4, a current detector U1, a diode D1, and a transistor Q36. The power supply VBAT is connected to the overcurrent protection switch portion (M2) via the resistor R4. The two input terminals of the current detector U1 are respectively connected to the two ends of the resistor R4. The output terminal pin 6 of the current detector U1 is connected to the base terminal pin 1 of the transistor Q36 via the diode D1. The collector terminal pin 3 of the transistor Q36 is connected to the overcurrent protection switch portion (M2). The emitter terminal pin 2 of the transistor Q36 is grounded. The output terminal pin 6 of the current detector U1 is grounded via the resistor R3.

[0032] The overcurrent protection switch portion (M2) includes a resistor R1, a resistor R2, a transistor Q37, and a MOS transistor Q1. The power supply VBAT is connected to the MOS transistor Q1 via a resistor R4. The MOS transistor Q1 is grounded via a load RL. The power supply VBAT is connected to the MOS transistor Q1 via a resistor R1. The power supply VBAT is connected to the base terminal pin 1 of the transistor Q37 via a resistor R2. The collector terminal pin 3 of the transistor Q37 is connected to the MOS transistor Q1. The emitter terminal pin 2 of the transistor Q37 is grounded. The collector terminal pin 3 of the transistor Q36 is connected to the base terminal pin 1 of the transistor Q37.

[0033] Specifically, the non-inverting input terminal pin 3 of the current detector U1 is connected to the pin 2 of one end of the resistor R4 connected to the power supply VBAT, the inverting input terminal pin 2 of the current detector U1 is connected to the other end pin 1 of the resistor R4, the ground terminal pin 4 of the current detector U1 is grounded, the output terminal pin 6 of the current detector U1 is connected to the base terminal pin 1 of the transistor Q36 via the diode D1, the collector terminal pin 3 of the transistor Q36 is connected to the overcurrent protection switch part (M2), and the emitter terminal pin 2 of the transistor Q36 is grounded.

[0034] More specifically, if Figure 1 As shown, one end, pin 2, of the resistor R4 and the non-inverting input terminal, pin 3, of the current detector U1 are both connected to the power supply VBAT, the other end, pin 1, of the resistor R4 is connected to the inverting input terminal, pin 2, of the current detector U1 and connected to the overcurrent protection switch part (M2), the output end, pin 6, of the current detector U1 and pin 1, of the resistor R3 are both connected to the positive terminal, pin 2, of the diode D1, the negative terminal, pin 1, of the diode D1 is connected to the base terminal, pin 1, of the transistor Q36, the collector terminal, pin 3, of the transistor Q36 is connected to the overcurrent protection switch part (M2), the emitter terminal, pin 2, of the transistor Q36, pin 2, of the resistor R3 and pin 4, of the current detector U1 are all grounded.

[0035] The current detector U1 uses an operational amplifier that operates as a differential amplifier.

[0036] Specifically, the overcurrent protection switch portion (M2) includes a resistor R1, a resistor R2, a transistor Q37, and a MOS transistor Q1. The power supply VBAT is connected to the source terminal pin 3 of the MOS transistor Q1 via the resistor R4. The drain terminal pin 1 of the MOS transistor Q1 is grounded via the load RL. The power supply VBAT is connected to the gate terminal pin 2 of the MOS transistor Q1 via the resistor R1. The power supply VBAT is connected to the base terminal pin 1 of the transistor Q37 via the resistor R2. The collector terminal pin 3 of the transistor Q37 is connected to the gate terminal pin 2 of the MOS transistor Q1. The emitter terminal of the transistor Q37 is grounded. The collector terminal pin 3 of the transistor Q36 is connected to the base terminal of the transistor Q37.

[0037] More specifically, if Figure 1As shown, pin 1 of the resistor R4 and pin 2 of the inverting input terminal of the current detector U1 are connected, and are also connected to pin 3 of the source terminal of the MOS transistor Q1. Pin 1 of the drain terminal of the MOS transistor Q1 is grounded via the load RL. Pin 2 of the gate terminal of the MOS transistor Q1 is connected to pin 2 of the resistor R1 and pin 3 of the collector terminal of the transistor Q37. Pin 2 of the emitter terminal of the transistor Q37 is grounded. Pin 1 of the base terminal of the transistor Q37 is connected to pin 3 of the collector terminal of the transistor Q36 in the overcurrent detection part (M1) and is also connected to pin 2 of the resistor R2. Pin 1 of the resistor R2 and pin 1 of the resistor R1 are both connected to the power supply VBAT.

[0038] In this embodiment, current detector U1 is a current sensing chip, model ZXCT1109Q. Transistors Q36 and Q37 are both NPN transistors, model PDTC115EU. Diode D1 is a switching diode, model BAS21VMFHTE-17. MOSFET Q1 is a PMOS transistor, model SSM3J351R.LXGF. Resistor R4 is a loop current sampling resistor with a relatively low resistance. Power supply VBAT is the vehicle battery voltage of +12V. Resistors R1 and R2 are both 10K.

[0039] The anode of the diode D1 is connected to the output terminal pin 6 of the current detector U1, and the cathode is connected to the base terminal pin 1 of the transistor Q36.

[0040] The MOS tube Q1 is a PMOS tube, and the transistor Q36 and the transistor Q37 are both NPN tubes.

[0041] The protection circuit is applied to the vehicle controller. The power supply VBAT can be connected to the vehicle battery using the vehicle wiring harness to power the ECU controller. The load RL can be the controller's internal load, specifically the controller's internal sensors, switch lights and other loads.

[0042] The protection circuit includes a normal mode and a cyclic protection mode. When the current flowing through the resistor R4 is less than the overcurrent threshold value, the protection circuit operates in the normal mode; when the current flowing through the resistor R4 is greater than or equal to the overcurrent threshold value, the protection circuit operates in the cyclic protection mode.

[0043] Normal mode is as follows:

[0044] When the current flowing through resistor R4 is less than the overcurrent threshold, the difference between the two input terminals of the current detector U1 is the voltage drop of resistor R4. Since the voltage drop of resistor R4 is small, the voltage of pin 6 of the output terminal of the current detector U1 is less than the sum of the conduction voltage drop of diode D1 and the turn-on voltage of transistor Q36. The voltage of pin 6 of the output terminal of the current detector U1 is obtained by the voltage drop of diode D1 to obtain the base voltage of transistor Q36. At this time, the voltage difference V between the base terminal and the emitter terminal of transistor Q36 isBE If the voltage of transistor Q36 is less than the turn-on voltage, transistor Q36 is not turned on, and the power supply VBAT is connected to the ground through the internal diode between the base terminal pin 1 and the emitter terminal pin 2 of transistor Q37 through the resistor R2. At this time, the voltage difference V between the base terminal and the emitter terminal of transistor Q37 is BE If the voltage is greater than or equal to the turn-on voltage of transistor Q37, transistor Q37 is turned on, the gate terminal pin 2 of MOS tube Q1 is grounded, and the voltage of the source terminal pin 3 of MOS tube Q1 is the voltage of power supply VBAT after the voltage drop of resistor R4. The voltage difference V between the gate terminal and the source terminal of MOS tube Q1 is gs is less than the threshold voltage of the MOS tube Q1, the MOS tube Q1 is turned on, and the power supply VBAT supplies power to the load RL through the resistor R4 and the MOS tube Q1, so that the load can work normally.

[0045] The cyclic protection mode includes the protection mode and the self-recovery mode. The cyclic protection mode works in sequence according to the protection mode and the self-recovery mode.

[0046] The protection modes are as follows:

[0047] When the current flowing through resistor R4 is greater than or equal to the overcurrent threshold, the difference between the two input terminals of the current detector U1 is the voltage drop of resistor R4. Since the voltage drop of resistor R4 is large, the large voltage drop of resistor R4 here is compared with the voltage drop of resistor R4 in normal mode. In fact, no matter what mode, the voltage drop of resistor R4 is very small compared with the power supply VBAT. Then the voltage of pin 6 of the output terminal of the current detector U1 is greater than or equal to the sum of the conduction voltage drop of diode D1 and the turn-on voltage of transistor Q36. The voltage of pin 6 of the output terminal of the current detector U1 is obtained by the voltage drop of diode D1 to obtain the base voltage of transistor Q36. At this time, the voltage difference V between the base terminal and the emitter terminal of transistor Q36 is BE If the voltage is greater than or equal to the turn-on voltage of transistor Q36, transistor Q36 is turned on, and the base pin 1 of transistor Q37 is grounded through transistor Q36, thereby making the voltage difference V between the base terminal and the emitter terminal of transistor Q37 BE If the voltage is less than the turn-on voltage of transistor Q37, transistor Q37 will not conduct. The voltage of pin 2 of the gate terminal of MOS tube Q1 will be pulled up to the approximate power supply VBAT under the action of resistor R1. The voltage difference V between the gate terminal and the source terminal of MOS tube Q1 is gs If the voltage is greater than or equal to the threshold voltage of the MOS tube Q1, the MOS tube Q1 is not turned on, and the power supply VBAT cannot supply power to the load RL through the resistor R4 and the MOS tube Q1.

[0048] The self-recovery mode is as follows:

[0049] After the protection circuit works in protection mode, no current flows through the resistor R4, and the voltage of the pin 6 of the current detector U1 output terminal is 0 volts, so that the voltage difference V between the base terminal and the emitter terminal of the transistor Q36 is BE is less than the turn-on voltage of transistor Q36, transistor Q36 is not turned on, making the voltage difference V between the base terminal and the emitter terminal of transistor Q37 BE If the voltage is greater than or equal to the turn-on voltage of transistor Q37, transistor Q37 is turned on, the gate terminal pin 2 of MOS tube Q1 is grounded, and the voltage of the source terminal pin 3 of MOS tube Q1 is the voltage of power supply VBAT after the voltage drop of resistor R4. The voltage difference V between the gate terminal and the source terminal of MOS tube Q1 is gs When the voltage is lower than the threshold voltage of MOS tube Q1, MOS tube Q1 is turned on, and then current flows through resistor R4;

[0050] Subsequently, if the current flowing through the resistor R4 is less than the overcurrent threshold value, the protection circuit operates in normal mode. If the current flowing through the resistor R4 is greater than or equal to the overcurrent threshold value, the protection circuit operates in a cyclic protection mode, that is, when the current flowing through the resistor R4 is continuously greater than or equal to the overcurrent threshold value, the protection circuit alternates between the protection mode and the self-recovery mode until the overcurrent fault is eliminated.

[0051] That is, after the self-recovery mode is completed, the current flowing through the resistor R4 is judged:

[0052] When the current flowing through resistor R4 is less than the overcurrent threshold, the protection circuit operates in normal mode;

[0053] When the current flowing through the resistor R4 is greater than or equal to the overcurrent threshold, the protection circuit returns to the protection mode and operates in the protection mode.

[0054] The protection circuit sets the overcurrent threshold by adjusting the resistance of resistor R4.

[0055] The overcurrent threshold value is specifically the maximum continuous current value allowed by the load RL under normal working conditions.

[0056] The following example uses the case where the resistance of R4 is 250mΩ, the resistance of R3 is 700Ω, and the overcurrent protection is 2A to illustrate different operating modes.

[0057] Normal mode: When the system is powered on and the current in the circuit is 1A, the voltage across the sampling resistor R4 is V R4 : 250mΩ*1A=0.25V. At this time, the output voltage of pin 6 of the current detector U1 chip is converted into the following formula:

[0058] V OUT =V R4 *0.004*R3=0.25V*0.004*700=0.7V

[0059] The condition for transistor Q36 to conduct is: the output voltage V OUT The voltage difference between the pin 2 of transistor Q36 is ≥1.4V, so V OUT Output voltage 0.7V < 1.4V, so transistor Q36 is not conducting, and its collector terminal 3 is not grounded. At this time, Q37 meets the conduction condition: the power supply VBAT passes through the resistor R2 and the base terminal 1 of transistor Q37 to the emitter terminal 2 to be grounded, meeting V BE ≥0.7V conduction condition, so the collector pin 3 of transistor Q37 is grounded. The gate 2 of PMOS transistor Q1 is connected to the collector of transistor Q37, and its MOS transistor gate potential is grounded. The source 3 of PMOS transistor Q1 is connected to VBAT power supply through resistor R4. Considering that the resistance of R4 is very small, its voltage drop can be ignored, so the V GS =0V-VBAT=-VBAT=-12V<-2.5V, which meets the PMOS tube conduction condition. Therefore, the VBAT power supply supplies power to the load RL through the resistor R4 and the PMOS tube, so that the load can work normally.

[0060] The cyclic protection mode includes the protection mode and the self-recovery mode. The cyclic protection mode works in accordance with the protection mode and the self-recovery mode in sequence.

[0061] Protection mode: When the current in the circuit becomes 2A due to a fault, the voltage across the sampling resistor R4 is V R4 : 250mR*2A=0.5V.

[0062] At this time, the output voltage of pin 6 of the current detector U1 chip is converted into the following formula: V OUT =V R4 *0.004*R3=0.5V*0.004*700=1.4V.

[0063] The condition for transistor Q36 to conduct is: the output voltage V OUT The voltage difference between the pin 2 of transistor Q36 is ≥ 1.4V, V OUT The output voltage meets the conduction condition, so transistor Q36 conducts and its collector terminal No. 3 is grounded. At this time, the base terminal No. 1 of transistor Q37 is forced to ground, making transistor Q37 non-conductive. Therefore, the collector terminal No. 3 of transistor Q37 is pulled up to VBAT by the action of resistor R1. The gate No. 2 of the PMOS tube is connected to the collector terminal No. 3 of transistor Q37, so its gate No. 2 potential is VBAT. The source terminal No. 3 of PMOS tube Q1 is connected to VBAT through resistor R4. Considering that the resistance value of R4 is very small, its voltage drop can be ignored, so the V GS=VABT-VBAT=0V>-2.5V, the conduction condition of PMOS tube Q1 is not met, PMOS tube Q1 is disconnected from power supply, and RL load is powered off.

[0064] Self-recovery mode:

[0065] The circuit enters the overcurrent protection state. At this time, the load RL is powered off, the voltage drop across the sampling resistor R4 is 0V, and the V OUT =V R4 *0.004*R3=0V*0.004*700=0V, the condition for transistor Q36 to be turned on: the output voltage V of pin 6 of current detector U1 OUT The voltage difference between the pin 2 of transistor Q36 is ≥ 1.4V. OUT Output voltage 0V < 1.4V, so transistor Q36 is not conducting and its No. 3 collector terminal is not grounded. At this time, transistor Q37 meets the conduction condition: the power supply VBAT passes through resistor R2 and transistor Q37 No. 1 base to No. 2 emitter grounded, meeting V BE ≥0.7V conduction condition, so the collector pin 3 of transistor Q37 is grounded. The gate 2 of PMOS transistor Q1 is connected to the collector of transistor Q37, and its MOS transistor gate potential is grounded. The source 3 of PMOS transistor Q1 is connected to VBAT power supply through resistor R4. Considering that the resistance of R4 is very small, its voltage drop can be ignored. The V GS =0V-VBAT=-VBAT=-12V<-2.5V, meeting the PMOS transistor conduction condition. Therefore, the VBAT power supply passes through resistor R4 and the PMOS transistor to supply power to the load RL. At this time, if the loop current is still greater than 2A, the system will enter the overcurrent protection state again, and the system will cycle between self-recovery mode and overcurrent mode until the overcurrent fault is eliminated and the system enters normal mode.

[0066] The above specific embodiments are used to illustrate the present invention rather than to limit the present invention. Any modifications and changes made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

[0067] The above description is only a preferred embodiment of the present invention. Therefore, any equivalent changes or modifications made according to the structure, characteristics and principles described in the scope of the patent application of the present invention are included in the scope of the patent application of the present invention.

Claims

1. A controller overcurrent protection circuit with adjustable value, characterized by: The invention comprises an overcurrent detection part (M1) and an overcurrent protection switch part (M2) connected to each other, wherein the overcurrent detection part (M1) is connected to a load RL via the overcurrent protection switch part (M2); The overcurrent detection part (M1) includes a resistor R3, a resistor R4, a current detector U1, a diode D1 and a transistor Q36, the power supply VBAT is connected to the overcurrent protection switch part (M2) via the resistor R4, the two input ends of the current detector U1 are respectively connected to the two ends of the resistor R4, the output end of the current detector U1 is connected to the transistor Q36 via the diode D1, the transistor Q36 is connected to the overcurrent protection switch part (M2), the transistor Q36 is grounded, and the output end of the current detector U1 is grounded via the resistor R3; The overcurrent protection switch part (M2) includes a resistor R1, a resistor R2, a transistor Q37 and a MOS transistor Q1. The power supply VBAT is connected to the MOS transistor Q1 via the resistor R4. The MOS transistor Q1 is grounded via the load RL. The power supply VBAT is connected to the MOS transistor Q1 via the resistor R1. The power supply VBAT is connected to the transistor Q37 via the resistor R2. The transistor Q37 is connected to the MOS transistor Q1. The transistor Q37 is grounded. The transistor Q36 is connected to the transistor Q37.

2. The controller overcurrent protection circuit with adjustable value according to claim 1, characterized in that: The non-inverting input terminal of the current detector U1 is connected to one end of the resistor R4 connected to the power supply VBAT, the inverting input terminal of the current detector U1 is connected to the other end of the resistor R4, the ground terminal of the current detector U1 is grounded, the output terminal of the current detector U1 is connected to the base terminal of the transistor Q36 via the diode D1, the collector terminal of the transistor Q36 is connected to the overcurrent protection switch part (M2), and the emitter terminal of the transistor Q36 is grounded.

3. The controller overcurrent protection circuit with adjustable value according to claim 2, characterized in that: The power supply VBAT is connected to the source terminal of the MOS transistor Q1 via the resistor R4, the drain terminal of the MOS transistor Q1 is grounded via the load RL, the power supply VBAT is connected to the gate terminal of the MOS transistor Q1 via the resistor R1, the power supply VBAT is connected to the base terminal of the transistor Q37 via the resistor R2, the collector terminal of the transistor Q37 is connected to the gate terminal of the MOS transistor Q1, the emitter terminal of the transistor Q37 is grounded, and the collector terminal of the transistor Q36 is connected to the base terminal of the transistor Q37.

4. The controller overcurrent protection circuit with adjustable value according to claim 1, characterized in that: The anode of the diode D1 is connected to the output terminal of the current detector U1 , and the cathode is connected to the base terminal of the transistor Q36 .

5. The controller overcurrent protection circuit with adjustable value according to claim 1, characterized in that: The MOS transistor Q1 is a PMOS transistor, and the transistor Q36 and the transistor Q37 are both NPN transistors.

6. The controller overcurrent protection circuit with adjustable value according to claim 1, characterized in that: The protection circuit is applied to a vehicle-mounted controller, the power supply VBAT is connected to a vehicle-mounted battery using a vehicle-mounted wiring harness, and the load RL is an internal load of the controller.

7. The adaptive overcurrent protection method applied to the protection circuit according to any one of claims 1 to 6, characterized in that: The protection circuit includes a normal mode and a cyclic protection mode. When the current flowing through the resistor R4 is less than the overcurrent threshold, the protection circuit operates in the normal mode; When the current flowing through the resistor R4 is greater than or equal to the overcurrent threshold, the protection circuit operates in a cyclic protection mode.

8. The adaptive overcurrent protection method for a protection circuit according to claim 7, wherein: The normal mode is specifically: When the current flowing through the resistor R4 is less than the overcurrent threshold, the difference between the two input terminals of the current detector U1 is the voltage drop of the resistor R4, and the voltage at the output terminal of the current detector U1 is less than the sum of the conduction voltage drop of the diode D1 and the turn-on voltage of the transistor Q36. At this time, the voltage difference V between the base terminal and the emitter terminal of the transistor Q36 is BE is less than the turn-on voltage of transistor Q36, transistor Q36 is not conducting, and the voltage difference V between the base terminal and the emitter terminal of transistor Q37 is BE The transistor Q37 is turned on, the gate terminal of the MOS tube Q1 is grounded, and the source terminal voltage of the MOS tube Q1 is the voltage of the power supply VBAT after the voltage drop of the resistor R4. The voltage difference between the gate terminal and the source terminal of the MOS tube Q1 is V gs is less than the threshold voltage of the MOS tube Q1, the MOS tube Q1 is turned on, and the power supply VBAT supplies power to the load RL through the resistor R4 and the MOS tube Q1.

9. The adaptive overcurrent protection method for a protection circuit according to claim 7, wherein: The cyclic protection mode includes a protection mode and a self-recovery mode, and the cyclic protection mode works in sequence according to the protection mode and the self-recovery mode; The protection mode is specifically: When the current flowing through the resistor R4 is greater than or equal to the overcurrent threshold, the difference between the two input terminals of the current detector U1 is the voltage drop of the resistor R4, and the voltage at the output terminal of the current detector U1 is greater than or equal to the sum of the conduction voltage drop of the diode D1 and the turn-on voltage of the transistor Q36. At this time, the voltage difference V between the base terminal and the emitter terminal of the transistor Q36 is BE If the voltage is greater than or equal to the turn-on voltage of transistor Q36, transistor Q36 is turned on, and the base of transistor Q37 is grounded through transistor Q36, thereby making the voltage difference V between the base terminal and the emitter terminal of transistor Q37 BE If the voltage is less than the turn-on voltage of transistor Q37, transistor Q37 will not conduct. The gate terminal voltage of MOS tube Q1 is pulled up to the power supply VBAT by resistor R1. The voltage difference V between the gate terminal and the source terminal of MOS tube Q1 is gs If the voltage is greater than or equal to the threshold voltage of the MOS tube Q1, the MOS tube Q1 is not turned on, and the power supply VBAT cannot supply power to the load RL through the resistor R4 and the MOS tube Q1; The self-recovery mode is specifically: After the protection circuit works in protection mode, no current flows through the resistor R4, and the output voltage of the current detector U1 is 0 volts, so that the voltage difference V between the base terminal and the emitter terminal of the transistor Q36 is BE is less than the turn-on voltage of transistor Q36, transistor Q36 is not turned on, making the voltage difference V between the base terminal and the emitter terminal of transistor Q37 BE The transistor Q37 is turned on, the gate terminal of the MOS tube Q1 is grounded, and the source terminal voltage of the MOS tube Q1 is the voltage of the power supply VBAT after the voltage drop of the resistor R4. The voltage difference between the gate terminal and the source terminal of the MOS tube Q1 is V gs When the voltage is lower than the threshold voltage of MOS tube Q1, MOS tube Q1 is turned on, and then current flows through resistor R4; Then judge the current flowing through resistor R4: When the current flowing through resistor R4 is less than the overcurrent threshold, the protection circuit operates in normal mode; When the current flowing through the resistor R4 is greater than or equal to the overcurrent threshold, the protection circuit returns to the protection mode and operates in the protection mode.

10. The adaptive overcurrent protection method for a protection circuit according to claim 7, wherein: The protection circuit sets the overcurrent threshold value by adjusting the resistance of the resistor R4.

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