MOS tube high-side driving voltage type short circuit protection circuit
By introducing a short-circuit protection circuit into the high-side drive circuit of the MOSFET, and using components such as operational amplifiers and optocouplers to detect and turn off load short circuits, the problem of damage to the MOSFET switching circuit during short circuits is solved, thus improving the reliability and safety of the system.
Patent Information
- Application Number
- CN202520369867.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-05
- Publication Date
- 2026-02-24
- Estimated Expiration
- 2035-03-05
AI Technical Summary
Existing MOSFET switching circuits are prone to burnout when the load is short-circuited, and existing protection circuits are complex or ineffective, resulting in high maintenance costs and poor system reliability and safety.
A short-circuit protection circuit is introduced into the high-side drive circuit of the MOSFET, including components such as operational amplifiers, optocouplers, thyristors, and transistors. By detecting a short circuit in the load, the MOSFET is quickly turned off to avoid damage.
It effectively protects MOSFETs and other components, improves system reliability and security, reduces maintenance costs, and enhances user experience.
Smart Images
Figure CN223942682U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of short circuit protection technology, specifically relating to a MOS transistor high-side drive voltage type short circuit protection circuit. Background Technology
[0002] MOS switching circuits utilize the switching characteristics of MOSFETs to control current flow and are widely used in power management, motor control, LED driving, and other fields. Some circuits have protection circuits, while others do not. Without protection circuits, a short circuit in the load will burn out the MOSFET. Some circuits do have protection circuits, but existing protection circuits are complex and cannot effectively protect the MOSFET after a short circuit, requiring a restart of the input power supply after a short circuit occurs. Utility Model Content
[0003] The purpose of this invention is to provide a short-circuit protection circuit for the high-side drive voltage of a MOSFET. This circuit ensures the safety of the MOSFET by adding a short-circuit protection to the high-side drive of the MOSFET.
[0004] To achieve the above objectives, the present invention adopts the following technical solution:
[0005] A MOSFET high-side drive voltage type short-circuit protection circuit includes a MOSFET and a drive circuit connected to the MOSFET, wherein a short-circuit protection circuit is connected between the output terminal of the MOSFET and the drive circuit.
[0006] The driving circuit includes transistors T1 and T2, capacitor C1, resistors R1 and R2, and diode D1. Transistor T1 is an NPN transistor, and transistor T2 is a PNP transistor. The base (B) of both transistors T1 and T2 is connected to the signal control terminal. The collector (C) of transistor T1 is connected to a voltage source, and the collector (C) of transistor T2 is grounded. The emitter (E) of transistors T1 and T2 is connected to each other. A parallel RC circuit consisting of capacitor C1, resistors R1 and R2 is also connected at the connection point. A diode D1 is connected in parallel to the RC circuit. The output of the RC circuit is connected to the gate (G) of a MOSFET. The drain (D) of the MOSFET is connected to the operating voltage VCC, and the source (S) of the MOSFET is connected to the load RL.
[0007] The short-circuit protection circuit includes an operational amplifier A, an optocoupler OP1, a diode D2, and a thyristor SCR. The non-inverting input of operational amplifier A is connected to the operating voltage VCC. A diode D3 is also connected to the non-inverting input of operational amplifier A. The inverting input of operational amplifier A is connected to the source (S) terminal of the MOSFET. The output of operational amplifier A is connected to the input of optocoupler OP1. The output of optocoupler OP1 is connected to the anode of diode D2. The cathode of diode D2 is connected to the control terminal of the thyristor SCR. The anode of the thyristor SCR is connected between resistors R1 and R2 in the RC circuit connecting the drive circuit. The cathode of the thyristor SCR is connected to the source (S) terminal of the MOSFET. A transistor T3 is also connected to the non-inverting input of operational amplifier A. The base (B) of transistor T3 is connected to the junction of the emitter (E) terminals of transistors T1 and T2. The emitter (E) terminal of transistor T3 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 voltage 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 1As shown, the driving circuit includes transistors T1 and T2, capacitor C1, resistors R1 and R2, and diode D1. Transistor T1 is an NPN transistor, and transistor T2 is a PNP transistor. The base (B) of both transistors T1 and T2 is connected to the signal control terminal Uqd. The collector (C) of transistor T1 is connected to voltage Vqd, and the collector (C) of transistor T2 is grounded. The emitter (E) of transistors T1 and T2 is connected. A parallel RC circuit consisting of capacitor C1, resistors R1 and R2 is also connected at the connection point. A diode D1 is connected in parallel to the RC circuit. The output of the RC circuit is connected to the gate (G) of MOSFET Q1. The drain (D) of MOSFET Q1 is connected to the operating voltage VCC, and the source (S) of MOSFET Q1 is connected to the load RL.
[0012] Driving principle: When the signal control terminal Uqd is high, transistor T1 saturates and conducts. The driving voltage is accelerated by capacitor C1 and directly drives MOSFET Q1. Resistors R1 and R2 transfer the driving voltage to the gate (G) of MOSFET Q1 through potential transfer, keeping MOSFET Q1 continuously conducting and energizing the load RL. When the signal control terminal Uqd is low, transistor T2 saturates and conducts. The charge at the gate (G) of MOSFET Q1 is rapidly released through diode D1, turning off MOSFET Q1 and de-energizing the load RL.
[0013] The short-circuit protection circuit includes operational amplifier A, optocoupler OP1, diode D2, and thyristor SCR. The non-inverting input (+) of operational amplifier A is connected to the operating voltage VCC through resistor R9. This non-inverting input (+) is also connected to the cathode of diode D3. The anode of diode D3 is connected to the inverting input (-) of operational amplifier A. The inverting input (-) of operational amplifier A is connected to the source (S) of MOSFET Q1 through resistor R7. The output of operational amplifier A is connected to the input of optocoupler OP1 through resistor R5. The output of optocoupler OP1 is connected to the anode of diode D2. The cathode of diode D2 is connected to the control electrode of thyristor SCR. The anode of thyristor SCR is connected between resistors R1 and R2 in the RC circuit connecting the drive circuit. The cathode of thyristor SCR is connected to the source (S) of the output of MOSFET Q1. The power supply terminal of thyristor SCR is connected to the operating voltage VCC through resistor R4, and its ground terminal is grounded. The non-inverting input + of the operational amplifier A is connected to the collector (C) of transistor T3 through resistor R8. The base (B) of transistor T3 is connected to the junction of the emitter (E) of transistor T1 and the emitter (E) of transistor T2 through resistor R6. The emitter (E) of transistor T3 is grounded.
[0014] Short circuit protection working principle: When the signal control terminal Uqd is high, transistor T1 is saturated and turned on. The drive signal drives MOSFET Q1 and also drives transistor T3 to turn on, resulting in a 10V reference voltage at the non-inverting input of operational amplifier A. The output voltage Vout of the output terminal S of MOSFET Q1 is 12V, and the voltage at the inverting input - of operational amplifier A is also 12V. Operational amplifier A is inverted biased, and its output voltage is 0V.
[0015] If a short circuit to ground occurs at this time, the output voltage Vout is forcibly pulled down to 0V. The process of the output voltage Vout dropping to 0V is extremely short. When the output voltage Vout drops to slightly below 10V, the operational amplifier A is positively biased, and its output immediately reverses to a high level, driving the optocoupler OP1 to conduct. The output of the optocoupler OP1 directly triggers the thyristor SCR to conduct, blocking the drive voltage of the MOSFET Q1. Q1 is forcibly turned off, thereby realizing the short circuit protection function.
[0016] If the short circuit occurs before the drive begins, the output voltage Vout is 0, operational amplifier A is forward biased, optocoupler OP1 is on, SCR is on, and the drive voltage of MOSFET Q1 is blocked. If the control signal terminal Uqd is high at this time, MOSFET Q1 will briefly turn on for 2µs and then immediately turn off. Without a short circuit, within the 2µs of accelerated drive via capacitor C1, MOSFET Q1 is fully turned on (only tens of ns), the output voltage Vout rises rapidly to 12V, operational amplifier A is inverted biased, its output is 0V, and optocoupler OP1 is off. Since capacitor C1 is equivalent to a short circuit during accelerated drive, the voltage across resistors R1 and R2 is 0V, no current flows, and the thyristor SCR does not maintain current and returns to the blocking state. After 2µs, resistors R1 and R2 continue to drive MOSFET Q1 to conduct, and the drive is completed normally.
[0017] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any modifications and substitutions based on the technical solutions and utility model concepts provided by the present utility model should be covered within the protection scope of the present utility model.
Claims
1. A MOSFET high-side drive voltage-type short-circuit protection circuit, comprising a MOSFET and a drive circuit connected to the MOSFET, characterized in that, A short-circuit protection circuit is connected between the output terminal of the MOS transistor and the driving circuit. The driving circuit includes transistors T1 and T2, capacitor C1, resistors R1 and R2, and diode D1. Transistor T1 is an NPN transistor, and transistor T2 is a PNP transistor. The base (B) of both transistors T1 and T2 is connected to the signal control terminal. The collector (C) of transistor T1 is connected to a voltage source, and the collector (C) of transistor T2 is grounded. The emitter (E) of transistors T1 and T2 is connected to each other. A parallel RC circuit consisting of capacitor C1, resistors R1 and R2 is also connected at the connection point. A diode D1 is connected in parallel to the RC circuit. The output of the RC circuit is connected to the gate (G) of a MOSFET. The drain (D) of the MOSFET is connected to the operating voltage VCC, and the source (S) of the MOSFET is connected to the load RL. The short-circuit protection circuit includes an operational amplifier A, an optocoupler OP1, a diode D2, and a thyristor SCR. The non-inverting input of operational amplifier A is connected to the operating voltage VCC. A diode D3 is also connected to the non-inverting input of operational amplifier A. The inverting input of operational amplifier A is connected to the source (S) terminal of the MOSFET. The output of operational amplifier A is connected to the input of optocoupler OP1. The output of optocoupler OP1 is connected to the anode of diode D2. The cathode of diode D2 is connected to the control terminal of the thyristor SCR. The anode of the thyristor SCR is connected between resistors R1 and R2 in the RC circuit connecting the drive circuit. The cathode of the thyristor SCR is connected to the source (S) terminal of the MOSFET. A transistor T3 is also connected to the non-inverting input of operational amplifier A. The base (B) of transistor T3 is connected to the junction of the emitter (E) terminals of transistors T1 and T2. The emitter (E) terminal of transistor T3 is grounded.