Turn-off protection circuit

Abstract

A turn-off protection circuit disclosed by the present invention comprises a locking module, a pull-down module and a circuit breaking module which are electrically connected in sequence, the circuit breaking module comprises an mos transistor Q1, a triode Q2 and a resistor R1, one end of the resistor R1 is electrically connected with the source electrode of the mos transistor Q1, the collector electrode of the triode Q2 is electrically connected with the grid electrode of the mos transistor Q1, the base electrode of the triode Q2 is electrically connected with the source electrode of the mos transistor Q1, and the locking module is electrically connected with the pull-down module. The other end of the resistor R1 and the emitting electrode of the triode Q2 are grounded; the drain electrode of the mos tube Q1 is connected with a power supply VIN; the pull-down module comprises an mos transistor Q3 for pulling down the voltage of the grid electrode of the mos transistor Q1, the drain electrode of the mos transistor Q3 is electrically connected with the grid electrode of the mos transistor Q1, and the source electrode of the mos transistor Q3 is grounded; the locking module comprises an operational amplifier OA for locking the driving voltage of the mos transistor Q3, and the output end of the operational amplifier OA is electrically connected with the grid electrode of the mos transistor Q3. The device can realize multiple protection, and is high in reaction speed and high in reliability.

Description

Technical Field

[0001] The present invention relates to the field of electronic circuits, and in particular to a shutdown protection circuit. Background Art

[0002] In order to save costs and facilitate installation in daily life, fuses are generally used as short-circuit or overcurrent protection devices. However, fuses must be replaced after they are blown, and can only provide protection once. Moreover, the fuse will not disconnect until the current exceeds the rated current for a period of time. The reaction time is too long, which may cause the back-end equipment to be burned out, and the reliability is not high. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, an object of the present invention is to provide a shutdown protection circuit which can achieve multiple protections, has a fast response speed and high reliability.

[0004] The purpose of the present invention is achieved by the following technical solutions: A shutdown protection circuit, comprising a locking module, a pull-down module and a circuit breaker module electrically connected in sequence, wherein the circuit breaker module comprises a MOS tube Q1, a transistor Q2 and a resistor R1, one end of the resistor R1 is electrically connected to the source of the MOS tube Q1, the collector of the transistor Q2 is electrically connected to the gate of the MOS tube Q1, the base of the transistor Q2 is electrically connected to the source of the MOS tube Q1, the other end of the resistor R1 and the emitter of the transistor Q2 are both grounded, and the drain of the MOS tube Q1 is connected to the power supply VIN; The pull-down module includes a MOSFET Q3 for pulling down the gate voltage of the MOSFET Q1, the drain of the MOSFET Q3 is electrically connected to the gate of the MOSFET Q1, the source of the MOSFET Q3 is grounded, and when the MOSFET Q3 is turned on, the MOSFET Q1 is turned off; The locking module includes an operational amplifier OA for locking the driving voltage of the MOSFET Q3 , and an output end of the operational amplifier OA is electrically connected to the gate of the MOSFET Q3 .

[0005] Preferably, the circuit breaker module further includes a resistor R2 and a resistor R3, one end of the resistor R2 is electrically connected to the gate of the MOSFET Q1, the other end of the resistor R2 is electrically connected to a power supply VCC, and the resistor R3 is connected in parallel to the transistor Q2.

[0006] Preferably, the pull-down module also includes a resistor R4 and a resistor R5, one end of each of the resistors R4 and R5 are electrically connected to the output end of the operational amplifier OA, the other end of the resistor R4 is electrically connected to the gate of the MOS tube Q3, and the other end of the resistor R5 is electrically connected to the power supply VCC.

[0007] Preferably, the locking module also includes a resistor R6, a resistor R7 and a resistor R8, one end of the resistor R6 is electrically connected to an input end of the operational amplifier OA, one end of the resistor R7 and one end of the resistor R8 are both electrically connected to the other end of the resistor R6, the other end of the resistor R7 is electrically connected to the power supply VCC, and the other end of the resistor R8 is electrically connected to the source of the MOS tube Q3.

[0008] Preferably, the locking module further includes a diode D1, an anode of the diode D1 is electrically connected to the input end of the operational amplifier OA, and a cathode of the diode D1 is electrically connected to an end of the resistor R6 close to the operational amplifier OA.

[0009] Preferably, the locking module further includes a resistor R9 and a resistor R10, the cathode of the diode D1 is electrically connected to the resistor R6 through the resistor R9, and the other input end of the operational amplifier OA is electrically connected to the drain of the MOS tube Q3 through the resistor R10.

[0010] Preferably, the shutdown protection circuit further includes a control module, and the control module is electrically connected to the power supply VCC and the source of the MOS tube Q1 respectively.

[0011] Preferably, the control module includes an electrically connected power resetter and a timer, the power resetter is electrically connected to the power supply VCC, and the timer is electrically connected to the source of the MOS tube Q1.

[0012] Preferably, the power resetter is a delayed reset switch, and the timer is a controllable counter.

[0013] Preferably, the operational amplifier OA is an instantaneous operational amplifier, and the transistor Q2 is a fast transistor.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The shutdown protection circuit disclosed in the present application realizes short circuit or overcurrent protection of the circuit by shutting down the MOS tube Q1, and the MOS tube Q1 can be shut down many times, so it can realize multiple protection circuits. In addition, the shut-down time of the MOS tube Q1 and the conduction time of the MOS tube Q3 are very short, which can reach tens of nanoseconds, with fast response speed and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A principle block diagram of an implementation of a shutdown protection circuit of the present invention; Figure 2 A circuit schematic diagram of an implementation of a shutdown protection circuit of the present invention; Figure 3A principle block diagram of another implementation of the shutdown protection circuit of the present invention; Figure 4 It is a circuit principle diagram of another implementation manner of the shutdown protection circuit of the present invention.

[0016] In the figure: 1. Locking module; 2. Pull-down module; 3. Circuit breaker module. DETAILED DESCRIPTION

[0017] In order to more clearly understand the specific technical solutions, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0018] like Figure 1-Figure 2 As shown, the shutdown protection circuit disclosed in the present application includes a locking module 1, a pull-down module 2 and a circuit breaker module 3 which are electrically connected in sequence, the circuit breaker module 3 includes a MOS tube Q1, a transistor Q2 and a resistor R1, one end of the resistor R1 is electrically connected to the source of the MOS tube Q1, the collector of the transistor Q2 is electrically connected to the gate of the MOS tube Q1, the base of the transistor Q2 is electrically connected to the source of the MOS tube Q1, the other end of the resistor R1 and the emitter of the transistor Q2 are grounded, and the drain of the MOS tube Q1 is connected to the power supply VIN; The pull-down module 2 includes a MOSFET Q3 for pulling down the gate voltage of the MOSFET Q1, the drain of the MOSFET Q3 is electrically connected to the gate of the MOSFET Q1, the source of the MOSFET Q3 is grounded, and when the MOSFET Q3 is turned on, the MOSFET Q1 is turned off; the locking module 1 includes an operational amplifier OA for locking the driving voltage of the MOSFET Q3, and the output end of the operational amplifier OA is electrically connected to the gate of the MOSFET Q3.

[0019] The shutdown protection circuit disclosed in the present application realizes short circuit or overcurrent protection of the circuit by shutting down the MOS tube Q1, and the MOS tube Q1 can be shut down many times, so multiple protections can be realized. The shut-down time of the MOS tube Q1 and the conduction time of the MOS tube Q3 are very short, which can reach tens of nanoseconds. When the MOS tube Q3 is turned on, the MOS tube Q1 is immediately turned off, with fast response speed and high reliability. When the MOS tube Q3 is disconnected, the MOS tube Q1 can be turned on again and has a self-recovery function. The power supply VIN provides power to the MOS tube Q1.

[0020] When the MOS tube Q1 is turned on, the current flows through R1 to GND. According to Ohm's law, a voltage drop is generated on R1. The transistor Q2 is turned on to lower the gate (drive) voltage of the MOS tube Q1, and the MOS tube Q1 is disconnected to play a protective role. The MOS tube Q3 can also lower the drive voltage of the MOS tube Q1, and the operational amplifier OA can lock the drive voltage of the MOS tube Q3, so that the MOS tube Q3 is turned on or off.

[0021] like Figure 2 As shown, in a preferred embodiment, the circuit breaker module further includes a resistor R2 and a resistor R3, one end of the resistor R2 is electrically connected to the gate of the MOS tube Q1, the other end of the resistor R2 is electrically connected to the power supply VCC, and the resistor R3 is connected in parallel with the transistor Q2. The pull-down module further includes a resistor R4 and a resistor R5, one end of the resistor R4 and the resistor R5 are electrically connected to the output end of the operational amplifier OA, the other end of the resistor R4 is electrically connected to the gate of the MOS tube Q3, and the other end of the resistor R5 is electrically connected to the power supply VCC.

[0022] In the above embodiment, the power supply VCC can supply power to the MOSFET Q1 and the MOSFET Q3, and the resistors R2, R3, R4 and R5 all play a role of voltage division. The resistance ratio of the resistor R2 and the resistor R3 is determined according to the on-voltage of the transistor Q2, and the resistance ratio of the resistor R4 and the resistor R5 is determined according to the driving voltage of the MOSFET Q3. Among them, the resistor R2 can also be used as a sampling resistor to collect the gate voltage of the MOSFET Q1.

[0023] like Figure 2 As shown, in a preferred embodiment, the locking module further includes a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10 and a diode D1, one end of the resistor R6 is electrically connected to an input end of the operational amplifier OA, one end of the resistor R7 and the resistor R8 are both electrically connected to the other end of the resistor R6, the other end of the resistor R7 is electrically connected to the power supply VCC, and the other end of the resistor R8 is electrically connected to the source of the MOS tube Q3. The anode of the diode D1 is electrically connected to the input end of the operational amplifier OA, and the cathode of the diode D1 is electrically connected to an end of the resistor R6 close to the operational amplifier OA. The cathode of the diode D1 is electrically connected to the resistor R6 through the resistor R9, and the other input end of the operational amplifier OA is electrically connected to the drain of the MOS tube Q3 through the resistor R10.

[0024] In the above embodiment, when the current flowing through R1 is greater than the set value, the transistor Q2 is quickly turned on (the turn-on time can reach tens of nanoseconds), the gate voltage of the MOS tube Q1 changes from a high level to a low level, and the pin 2 of the operational amplifier OA changes from a high level to a low level (within a few microseconds). When the level of pin 2 of the operational amplifier OA is less than the level of pin 3, when the output pin 1 of the operational amplifier OA becomes a high level, the diode D1 is turned on, and the pin 3 of the operational amplifier OA is locked to a high level. The MOS tube Q3 is always turned on, the gate voltage of the MOS tube Q1 is always pulled down, and the MOS tube Q1 is never turned on and is disconnected, thereby achieving continuous overcurrent protection.

[0025] The resistors R6, R7 and R8 are used for voltage division, the resistors R9 and R10 can prevent the input current of the operational amplifier OA from being too large, and the operational amplifier OA is also electrically connected to the power supply VCC.

[0026] like Figure 3-Figure 4 As shown, in a preferred embodiment, the shutdown protection circuit further includes a control module, and the control module is electrically connected to the power supply VCC and the source of the MOS tube Q1 respectively. The control module includes an electrically connected power resetter and a timer, the power resetter is electrically connected to the power supply VCC, and the timer is electrically connected to the source of the MOS tube Q1. Preferably, the power resetter is a delayed reset switch, and the timer is a controllable counter.

[0027] In the above embodiment, when the shutdown protection circuit is in the overcurrent protection mode, in order to release the protection mode, it is necessary to restart the operational amplifier OA, and a control module is set. The power resetter of the control module can restart the power supply of the operational amplifier OA and other power supplies VCC, and restart the operational amplifier OA. The timer of the control module can count the on and off time of the MOS tube Q1, and the power resetter can restart the power supply VCC according to the time counted by the timer (the value of the time can be manually set), so as to realize automatic control. The delayed reset switch can restart the power supply VCC according to the time, and the controllable counter can manually set the threshold of the counted time. In order to improve the reaction time of the shutdown protection circuit, the operational amplifier OA is an instantaneous operational amplifier, and the transistor Q2 is a fast transistor.

[0028] In summary, the shutdown protection circuit adopts a pure hardware method to build the circuit, with fast response speed and high reliability; the short circuit is achieved by turning off the MOS tube Q1, multiple protection circuits can be realized, and the short circuit protection function can be automated through the control module; it is built with simple discrete devices (resistors, diodes, triodes and MOS tubes), and no integrated chip is used for design, the circuit structure is simple, and the hardware cost is low.

[0029] The basic principles, main features and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and the description in the specification are only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A shutdown protection circuit, characterized in that: It includes a locking module, a pull-down module and a circuit breaker module which are electrically connected in sequence, and the circuit breaker module includes a MOS The invention relates to a MOSFET Q1, a triode Q2 and a resistor R1, wherein one end of the resistor R1 is electrically connected to the source of the MOSFET Q1, the collector of the triode Q2 is electrically connected to the gate of the MOSFET Q1, the base of the triode Q2 is electrically connected to the source of the MOSFET Q1, the other end of the resistor R1 and the emitter of the triode Q2 are both grounded, and the drain of the MOSFET Q1 is connected to a power supply VIN; the pull-down module comprises a MOSFET Q3 for pulling down the gate voltage of the MOSFET Q1, the drain of the MOSFET Q3 is electrically connected to the gate of the MOSFET Q1, the source of the MOSFET Q3 is grounded, and when the MOSFET Q3 is turned on, the MOSFET Q1 is turned off; the locking module comprises an operational amplifier OA for locking the driving voltage of the MOSFET Q3, and the output end of the operational amplifier OA is electrically connected to the gate of the MOSFET Q3.

2. The shutdown protection circuit according to claim 1, characterized in that: The circuit breaker module further includes a resistor R2 and a resistor R3, one end of the resistor R2 is electrically connected to the gate of the MOSFET Q1, the other end of the resistor R2 is electrically connected to a power source VCC, and the resistor R3 is connected in parallel to the transistor Q2.

3. The shutdown protection circuit according to claim 1, characterized in that: The pull-down module also includes a resistor R4 and a resistor R5, one end of each of which is electrically connected to the output end of the operational amplifier OA, the other end of the resistor R4 is electrically connected to the gate of the MOS tube Q3, and the other end of the resistor R5 is electrically connected to the power supply VCC.

4. The shutdown protection circuit according to claim 1, characterized in that: The locking module also includes a resistor R6, a resistor R7 and a resistor R8, one end of the resistor R6 is electrically connected to an input end of the operational amplifier OA, one end of the resistor R7 and one end of the resistor R8 are both electrically connected to the other end of the resistor R6, the other end of the resistor R7 is electrically connected to the power supply VCC, and the other end of the resistor R8 is electrically connected to the source of the MOS tube Q3.

5. The shutdown protection circuit according to claim 4, characterized in that: The locking module further includes a diode D1 , an anode of the diode D1 is electrically connected to the input end of the operational amplifier OA, and a cathode of the diode D1 is electrically connected to an end of the resistor R6 close to the operational amplifier OA.

6. The shutdown protection circuit according to claim 5, characterized in that: The locking module further includes a resistor R9 and a resistor R10, the cathode of the diode D1 is electrically connected to the resistor R6 through the resistor R9, and the other input end of the operational amplifier OA is electrically connected to the drain of the MOS tube Q3 through the resistor R10.

7. The shutdown protection circuit according to claim 1, characterized in that: The shutdown protection circuit further includes a control module, and the control module is electrically connected to the power source VCC and the source of the MOS tube Q1 respectively.

8. The shutdown protection circuit according to claim 7, characterized in that: The control module includes an electrically connected power resetter and a timer, wherein the power resetter is electrically connected to the power source VCC, and the timer is electrically connected to the source of the MOS tube Q1.

9. The shutdown protection circuit according to claim 8, characterized in that: The power resetter is a delayed reset switch, and the timer is a controllable counter.

10. The shutdown protection circuit according to claim 1, characterized in that: The operational amplifier OA is an instantaneous operational amplifier, and the transistor Q2 is a fast transistor.

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