MOS tube high-side driving current type short-circuit protection circuit

Abstract

The utility model belongs to the technical field of short-circuit protection, and particularly relates to an MOS tube high-side driving current type short-circuit protection circuit, which comprises an MOS tube and a driving circuit connected with the MOS tube, and the short-circuit protection circuit is connected between the output end of the MOS tube and the driving circuit. According to the utility model, the reliability, the safety and the service life of the circuit can be effectively improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to short circuit protection technical field, concretely relates to a MOS pipe high side drive current type short circuit protection circuit. BACKGROUND

[0002] MOS switch circuit utilizes the switching characteristic of MOS pipe to control the on-off of current, and is widely applied in power management, motor control, LED drive and other fields. Some circuits are provided with protection circuit, and some of the above-mentioned circuits are not provided with protection circuit. If the protection circuit is not used, the load will burn the MOS pipe if short-circuit occurs. Some of the above-mentioned circuits are provided with protection circuit, but the existing protection circuit is complex to set, and cannot well protect the MOS pipe after short-circuit occurs. After short-circuit occurs, the input power needs to be restarted. UTILITY MODEL CONTENTS

[0003] The utility model aims at providing a MOS pipe high side drive current type short circuit protection circuit, which adds a short circuit protection to the MOS pipe high side drive, and ensures the safety of the MOS pipe.

[0004] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme:

[0005] A MOS pipe high side drive current type short circuit protection circuit, comprising a MOS pipe and a drive circuit connected with the MOS pipe, wherein a short circuit protection circuit is connected between the output end of the MOS pipe and the drive circuit.

[0006] The drive circuit comprises an optical coupler isolator OP1, a triode P1, a triode P2, a capacitor C1, a diode D1, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a resistor R5. The input end of the optical coupler isolator OP1 is connected with a control signal through the resistor R1, the output end thereof is connected with the B electrode of the triode P2 through the resistor R3, the E electrode of the triode P2 is connected with the B electrode of the triode P1, the E electrode of the triode P1 is connected with the B electrode of the triode P2 through the resistor R2, the C electrode of the triode P1 is connected with the C electrode of the triode P2, and then a parallel RC circuit composed of the capacitor C1 and the resistor R4 is connected, the RC circuit is connected with a diode D1 in parallel, the output end of the RC circuit is connected with the G electrode of the MOS pipe, the D electrode of the MOS pipe is connected with a working voltage Vbat, and the S electrode of the MOS pipe is connected with a load.

[0007] The short-circuit protection circuit includes a sampling resistor R0, an operational amplifier A1, a diode D2, a thyristor SCR, resistors 6, 7, 8, and 9. The sampling resistor R0 is connected between the source (S) terminal of the MOSFET Q2 and the load. The non-inverting input of the operational amplifier A1 is connected to the input terminal of the sampling resistor R0 through resistor R9, and its negative input is connected to the output terminal of the sampling resistor R0 through resistor R8. The output terminal of the operational amplifier A1 is connected to the negative input terminal of the operational amplifier A1 through resistor R7. The output terminal of the operational amplifier A1 is connected to the anode of the diode D2 through resistor R6. The cathode of the diode D2 is connected to the gate (G) terminal of the thyristor SCR. The aperture (A) terminal of the thyristor SCR is connected to the gate (G) terminal of the MOSFET Q2. The base (K) terminal of the thyristor SCR is grounded.

[0008] In a MOSFET switching circuit, when the load is short-circuited, a large current flows between the drain and source of the MOSFET, which may cause the MOSFET to overheat or even burn out, increasing maintenance costs. This invention adds a short-circuit protection circuit to the MOSFET switching circuit, which can effectively protect the MOSFET, power supply and other components, improve the reliability, safety and service life of the system, and at the same time reduce maintenance costs and improve user experience. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the circuit structure of this utility model. Detailed Implementation

[0010] This embodiment provides a MOSFET high-side drive current type short-circuit protection circuit, which includes a MOSFET, a drive circuit connected to the gate of the MOSFET, and a short-circuit protection circuit connected to the output side of the MOSFET and the drive circuit. When an accidental short circuit to ground occurs in the circuit, the short-circuit protection circuit protects the MOSFET and prevents damage to the MOSFET or other more serious situations.

[0011] like Figure 1 As shown, the driving circuit includes an optocoupler OP1, transistors P1 and P2, capacitor C1, diode D1, resistors R1, R2, R3, R4, and R5. The input of optocoupler OP1 is disconnected from the control signal via resistor R1. Its output is connected to the base (B) of transistor P2 via resistor R3. The emitter (E) of transistor P2 is connected to the base (B) of transistor P1. The emitter (E) of transistor P1 is connected to the base (B) of transistor P2 via resistor R2. The collector (C) of transistor P1 is connected to the collector (C) of transistor P2, and then a parallel RC circuit consisting of capacitor C1 and resistor R4 is connected to this RC circuit. A diode D1 is connected in parallel to this RC circuit, and the cathode of diode D1 is grounded via resistor R5. The output of the RC circuit is connected to the gate (G) of MOSFET Q2. The drain (D) of MOSFET Q2 is connected to the operating voltage Vbat, and the source (S) of MOSFET Q2 is connected to the load RL.

[0012] Driving principle: the signal control end is connected with the MCU of the central controller, the MCU gives a high level, the triode P1 and the triode P2 are saturated and conductive, the driving voltage is accelerated and directly drives the MOS tube Q2 through the capacitor C1, then the driving voltage is added to the G pole of the MOS tube Q2 through the potential transmission of the resistor R4, the MOS tube Q2 continuously conducts, and the load RL is powered.

[0013] The MCU gives a low level, the G pole charge of the MOS tube Q2 is rapidly released through the diode D1 and the resistor R3, the MOS tube Q2 is turned off, and the load RL loses power.

[0014] The short-circuit protection circuit comprises a sampling resistor R0, an operational amplifier A1, a diode D2, a thyristor SCR, resistors 6, 7, 8 and 9, the sampling resistor R0 is connected between the S pole of the MOS tube Q2 and the load RL and plays a role of collecting current, the same phase end + of the operational amplifier A1 is connected to the input end of the sampling resistor R0 through the resistor R9, the negative phase end - thereof is connected to the output end of the sampling resistor R0 through the resistor R8, the output end of the operational amplifier A1 is connected to the negative phase end - of the operational amplifier A1 through the resistor R7, the output end of the operational amplifier A1 is connected to the anode of the diode D2 through the resistor R6, the cathode of the diode D2 is connected to the G pole of the thyristor SCR, the A pole of the thyristor SCR is connected to the G pole of the MOS tube Q2, and the K pole of the thyristor SCR is grounded.

[0015] Short-circuit protection principle: in the short-circuit protection circuit, the sampling resistor R0 is equivalent to a current sensor, when an output-to-ground short circuit occurs, the MOS tube Q2 is driven, the current flowing through the sampling resistor R0 rapidly increases, the voltage drop on the sampling resistor R0 also rapidly increases, the thyristor SCR is directly triggered after being amplified by the operational amplifier A1, the thyristor SCR is turned on and rapidly pulls the driving voltage to 0V, the MOS tube Q2 is turned off, and the short-circuit protection is realized; the time from the short circuit to the short-circuit protection is about 50ns. When the driving signal is removed, the thyristor SCR loses the maintaining current and returns to the blocking state, and is ready for the next short-circuit protection. The short-circuit protection circuit of the embodiment can realize continuous short-circuit protection.

[0016] In normal operation, due to the low resistance and small voltage drop of the sampling resistor R0, even after passing through the operational amplifier A1, it is not enough to trigger the thyristor SCR, and the short-circuit protection does not work.

[0017] The above only describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, any modification and replacement based on the technical solutions and the application concept provided by the present application should be covered in the protection scope of the present application.

Claims

1. A MOS transistor high-side drive current type short circuit protection circuit comprising a MOS transistor and a drive circuit connected to the MOS transistor, characterized in that, The output end of the MOS transistor is connected with a short circuit protection circuit between the driving circuit; The driving circuit comprises an optical coupler isolator OP1, a transistor P1, a transistor P2, a capacitor C1, a diode D1, resistors R1, R2, R3, R4 and R5, the input end of the optical coupler isolator OP1 is connected with a control signal through the resistor R1, the output end of the optical coupler isolator OP1 is connected with the B electrode of the transistor P2 through the resistor R3, the E electrode of the transistor P2 is connected with the B electrode of the transistor P1, the E electrode of the transistor P1 is connected with the B electrode of the transistor P2 through the resistor R2, the C electrode of the transistor P1 is connected with the C electrode of the transistor P2, and then a parallel RC circuit composed of the capacitor C1 and the resistor R4 is connected, the RC circuit is connected with a diode D1 in parallel, the output end of the RC circuit is connected with the G electrode of the MOS transistor, the D electrode of the MOS transistor is connected with a working voltage Vbat, and the S electrode of the MOS transistor is connected with a load. The short circuit protection circuit comprises a sampling resistor R0, an operational amplifier A1, a diode D2, a thyristor SCR, resistors R6, R7, R8 and R9, the sampling resistor R0 is connected between the S electrode of the MOS transistor Q2 and the load, the same-phase end of the operational amplifier A1 is connected with the input end of the sampling resistor R0 through the resistor R9, and the negative-phase end of the operational amplifier A1 is connected with the output end of the sampling resistor R0 through the resistor R8; the output end of the operational amplifier A1 is connected with the negative-phase end of the operational amplifier A1 through the resistor R7, the output end of the operational amplifier A1 is connected with the anode of the diode D2 through the resistor R6, the cathode of the diode D2 is connected with the G electrode of the thyristor SCR, the A electrode of the thyristor SCR is connected with the G electrode of the MOS transistor Q2, and the K electrode of the thyristor SCR is grounded.

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