Self-recovery circuit for over-current protection of MOS (Metal Oxide Semiconductor) tube

Abstract

The utility model discloses a self-recovery circuit for over-current protection of an MOS (Metal Oxide Semiconductor) tube, which relates to the field of electronic components and comprises a signal input module for inputting an external trigger signal and outputting the signal to a feedback protection module after isolation; the clamp voltage module is used for limiting the voltage output to the feedback protection module to be within 20V, so that the circuit is prevented from being damaged; the feedback protection module is used for enabling the MOS tube to cut off the protection circuit when overcurrent and short circuit occur, and enabling the MOS tube to recover conduction after time delay after the overcurrent and short circuit are finished; the signal input module is connected with the clamp pressure module which is connected with the feedback protection module. Compared with the prior art, the circuit has the beneficial effects that overcurrent and short circuit protection is realized in a hardware mode, and compared with software protection, the circuit has the advantages of high speed and good stability, and the condition of protection failure after the MCU flies is completely eradicated.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic components field, concretely is a kind of self-recovery circuit for MOS tube overcurrent protection. BACKGROUND

[0002] MOS tube overcurrent protection is a very important protection measure in electronic circuit, which aims to quickly cut off or limit current when the current in the circuit exceeds the preset safety threshold, to prevent circuit and equipment from being damaged.

[0003] The existing MOS tube overcurrent is protected by software method, which is slow and has poor stability, and needs to be improved. UTILITY MODEL CONTENT

[0004] The utility model aims at providing a kind of self-recovery circuit for MOS tube overcurrent protection to solve the problems raised in the above background technology.

[0005] To achieve the above object, the utility model provides the following technical scheme:

[0006] A kind of self-recovery circuit for MOS tube overcurrent protection, comprising:

[0007] Signal input module is used to input external trigger signal, and output to feedback protection module after isolation;

[0008] Clamping voltage module is used to limit the voltage output to feedback protection module within 20V, to avoid damaging the circuit;

[0009] Feedback protection module is used to protect the circuit when overcurrent and short circuit occur, and MOS tube resumes conduction after delay when overcurrent and short circuit end.

[0010] Signal input module is connected with clamping voltage module, and clamping voltage module is connected with feedback protection module.

[0011] As a further scheme of the utility model: signal input module includes resistance R1, resistance R3, resistance R4, resistance R5, optocoupler Q2, diode LED2, diode LED3, resistance R9, resistance R15, one end of resistance R1 is connected with one end of resistance R3, one end of resistance R5, interface XCOM, the other end of resistance R5 is connected with negative electrode of diode LED2, the other end of resistance R3 is connected with positive electrode of diode LED3, positive electrode of diode LED2 is connected with negative electrode of diode LED3, one end of resistance R4, second end of optocoupler Q2, interface X00, the other end of resistance R1 is connected with the other end of resistance R4, first end of optocoupler Q2, fourth end of optocoupler Q2 is connected with 24V voltage, one end of resistance R9 is connected with third end of optocoupler Q2, the other end of resistance R9 is connected with one end of resistance R15, clamping voltage module, the other end of resistance R15 is grounded.

[0012] As a further improvement of this utility model, the optocoupler Q1 is model LV345T.

[0013] As a further embodiment of this utility model: the clamping module includes a resistor R11, a diode D32, and a diode D34. One end of the resistor R11 is connected to the signal input module, and the other end of the resistor R11 is connected to the negative terminal of the diode D32 and the feedback protection module. The positive terminal of the resistor D32 is connected to the positive terminal of the diode D34, and the negative terminal of the diode D34 is grounded.

[0014] As a further embodiment of this utility model: the feedback protection module includes diode D1, diode D3, capacitor C2, transistor Q100, resistor R100, capacitor C11, amplifier, capacitor C105, diode LED1, resistors R2, R13, and R16, diode D2, resistor R17, transistor Q3, resistor R8, resistor R12, MOSFET Q1, the gate of MOSFET Q1 is connected to the collector of transistor Q3, the anode of diode D1, the anode of diode D3, a clamping module, the cathode of diode D3 is connected to the signal input module, the cathode of diode D1 is connected to the output terminal of the amplifier, the cathode of diode LED1, the anode of diode LED1 is connected to one end of resistor R2, the other end of resistor R2 is connected to a 24V voltage, the drain of MOSFET Q1 is connected to the load, and the... The source (S) terminal is connected to one end of resistor R8, one end of resistor R12, one end of resistor R17, and the positive terminal of diode D2. The other end of resistor R8 is connected to the base of transistor Q3. The other end of resistor R12 is grounded. The emitter of transistor Q3 is grounded. The other end of resistor R17 is connected to the negative terminal of diode D2, the inverting input of the amplifier, one end of capacitor C2, and the collector of transistor Q100. The other end of capacitor C2 is grounded. The emitter of transistor Q100 is connected to a 12V voltage. One end of resistor R100 is connected to the base of transistor Q100. One end of capacitor C11 is connected to the negative terminal of diode LED1. The non-inverting input of the amplifier is connected to one end of resistor R13 and one end of resistor R16. The other end of resistor R13 is connected to a 12V voltage. The other end of resistor R16 is grounded.

[0015] Compared with the prior art, the beneficial effects of this utility model are: the present invention realizes overcurrent and short circuit protection through hardware, which has higher speed and better stability compared with software protection, and eliminates the situation where the protection fails after the MCU runs away. Attached Figure Description

[0016] Figure 1 This is a circuit diagram of a self-recovery circuit for overcurrent protection of a MOSFET. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0018] Please see Figure 1 A self-recovery circuit for overcurrent protection of a MOSFET, comprising:

[0019] The signal input module is used to input external trigger signals, which are then isolated and output to the feedback protection module.

[0020] The clamping module is used to limit the voltage output to the feedback protection module to within 20V to prevent damage to the circuit.

[0021] The feedback protection module is used to protect the MOSFET from overcurrent and short circuit. After the overcurrent and short circuit ends, the MOSFET resumes conduction after a delay.

[0022] The signal input module is connected to the clamping module, and the clamping module is connected to the feedback protection module.

[0023] In this embodiment: Please refer to Figure 1 The signal input module includes resistors R1, R3, R4, and R5, optocoupler Q2, diodes LED2 and LED3, resistors R9 and R15. One end of resistor R1 is connected to one end of resistor R3, one end of resistor R5, and interface XCOM. The other end of resistor R5 is connected to the negative terminal of diode LED2. The other end of resistor R3 is connected to the positive terminal of diode LED3. The positive terminal of diode LED2 is connected to the negative terminal of diode LED3. One end of resistor R4 is connected to the second end of optocoupler Q2 and interface X00. The other end of resistor R1 is connected to the other end of resistor R4 and the first end of optocoupler Q2. The fourth end of optocoupler Q2 is connected to a 24V voltage. The third end of optocoupler Q2 is connected to one end of resistor R9. The other end of resistor R9 is connected to one end of resistor R15 and clamping module. The other end of resistor R15 is grounded.

[0024] The external trigger signal is applied to nodes 1 and 2 through interfaces XCOM and X00. At this time, diode LED3 is energized and lit under the current limiting resistor R3. Resistor R5 and LED2 are connected in reverse to indicate that the input signal is reversed. The internal LED of optocoupler Q2 is also lit under the action of current limiting resistor R4, and then optocoupler Q2 is turned on. Node 4 is energized to form a high level.

[0025] In this embodiment: Please refer to Figure 1The model of optocoupler Q1 is LV345T.

[0026] In this embodiment: Please refer to Figure 1 The clamping module includes a resistor R11, a diode D32, and a diode D34. One end of the resistor R11 is connected to the signal input module, and the other end of the resistor R11 is connected to the negative terminal of the diode D32 and the feedback protection module. The positive terminal of the resistor D32 is connected to the positive terminal of the diode D34, and the negative terminal of the diode D34 is grounded.

[0027] After optocoupler Q2 is turned on, there is voltage on resistor R15, which is output to the clamping module. Zener diodes D32 and D34 form a voltage clamping circuit to limit the voltage to within 20V, preventing the voltage difference between the gate and source of the downstream MOSFET Q1 from being too large and causing damage to MOSFET Q1.

[0028] In this embodiment: Please refer to Figure 1 The feedback protection module includes diode D1, diode D3, capacitor C2, transistor Q100, resistor R100, capacitor C11, amplifier, capacitor C105, diode LED1, resistors R2, R13, and R16, diode D2, resistor R17, transistor Q3, resistor R8, resistor R12, and MOSFET Q1. The gate (G) of MOSFET Q1 is connected to the collector of transistor Q3, the anode of diode D1, the anode of diode D3, and a clamping module. The cathode of diode D3 is connected to the signal input module. The cathode of diode D1 is connected to the output of the amplifier and the cathode of diode LED1. The anode of diode LED1 is connected to one end of resistor R2, and the other end of resistor R2 is connected to a 24V voltage. The drain (D) of MOSFET Q1 is connected to the load, and the source (S) of MOSFET Q1 is connected to resistor R100. One end of resistor R8, one end of resistor R12, one end of resistor R17, the positive terminal of diode D2, the other end of resistor R8 is connected to the base of transistor Q3, the other end of resistor R12 is grounded, the emitter of transistor Q3 is grounded, the other end of resistor R17 is connected to the negative terminal of diode D2, the inverting input of amplifier, one end of capacitor C2, the collector of transistor Q100, the other end of capacitor C2 is grounded, the emitter of transistor Q100 is connected to 12V voltage, one end of resistor R100, the base of transistor Q100 is connected to the other end of resistor R100, one end of capacitor C11, the other end of capacitor C11 is connected to the negative terminal of diode LED1, the non-inverting input of amplifier is connected to one end of resistor R13, one end of resistor R16, the other end of resistor R13 is connected to 12V voltage, and the other end of resistor R16 is grounded.

[0029] During normal operation, the gate of MOSFET Q1 receives voltage, MOSFET Q1 conducts, and the load is grounded through MOSFET Q1 and resistor R12, forming a circuit, and the load is powered and works.

[0030] During self-recovering overcurrent protection, when an abnormal load occurs and the current increases, resistor R12 acts as a sampling resistor for the load current. Its voltage divider increases with the current increase. At node 12, the signal is input to the inverting input of the amplifier through resistor R17 and diode D2. The amplifier then acts as a voltage comparator, and its trigger voltage is determined by the resistor divider network at the non-inverting input. The values ​​of R13 and R16 in the diagram make the reference voltage 1.2K / (47k+1.2K)*12V=0.2987V. When the load current increases and just exceeds the set current value of 0.2987V, the signal quickly increases the voltage at the inverting input of the amplifier through diode D2, and the amplifier outputs 0V, pulling node 7 low. Diode LED1 is lit, and at the same time, node 5 is also pulled low by the amplifier output through diode D1. Consequently, the voltage difference between the gate and source of MOSFET Q1 is pulled down to 0V, MOSFET Q1 is cut off, and the load is protected.

[0031] Transistor Q100 is normally in the off state. When the amplifier outputs a low level momentarily, capacitor C11, whose voltage cannot change abruptly, momentarily turns on transistor Q100. The charging voltage of capacitor C2 at node 6 is +12V. In addition, due to the self-discharge circuit formed between capacitor C2, resistor R17 and sampling resistor R12, the voltage of capacitor C2 will automatically release after the overcurrent disappears. Adjusting the value of resistor R17 can adjust the self-recovery time.

[0032] During self-recovering short-circuit protection, if a short circuit exists at the output, the current flowing through MOSFET Q1 reaches its maximum value, and the voltage across sampling resistor R12 instantly reaches a peak value far exceeding 0.7V (the turn-on voltage of transistor Q3). Transistor Q3 instantly turns on, pulling down the voltage difference between the gate and source of MOSFET Q1, causing MOSFET Q1 to immediately turn off. However, since the current becomes 0 after turning off, there is no short circuit at this time, and the voltage division of sampling resistor R12 is 0, causing transistor Q3 to turn off. MOSFET Q1 then turns on again, and this phenomenon continues to cycle until capacitor C2 is fully charged, at which point the circuit automatically enters the above "self-recovering overcurrent protection" process.

[0033] In summary, this circuit provides overcurrent and short-circuit protection for the MOSFET and also enables self-recovery during hiccups.

[0034] by Figure 1 The specific component parameters shown are as follows: Node 13 is connected to the negative terminal of the load, and the positive terminal of the load is connected to the positive terminal of the 24V power supply; and a 24V DC power supply is supplied to the circuit. At this time, +24V is input at node 1, 0V is input at node 2, the load current is set to 2A, the MOSFET Q1 is normally turned on, and the load current is displayed as 2A.

[0035] At this point, the load current is set to 7A; the output is cut off, the diode LED1 indicator light is lit, the circuit overcurrent protection is activated, and after waiting for about 1 second, the diode LED1 indicator light goes out, the MOSFET Q1 is turned on again, then the diode LED1 is lit again, the MOSFET turns off the output again, and so on; the circuit works normally.

[0036] The working principle of this utility model is as follows: the signal input module is used to input external trigger signals, which are then isolated and output to the feedback protection module; the clamping module is used to limit the voltage output to the feedback protection module to within 20V to avoid damaging the circuit; the feedback protection module is used to cut off the MOSFET protection circuit when overcurrent or short circuit occurs, and after the overcurrent or short circuit ends, the MOSFET resumes conduction after a delay.

[0037] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects.

[0038] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A self-recovery circuit for overcurrent protection of a MOSFET, characterized in that, The self-recovery circuit for MOSFET overcurrent protection includes: The signal input module is used to input external trigger signals, which are then isolated and output to the feedback protection module. The clamping module is used to limit the voltage output to the feedback protection module to within 20V to prevent damage to the circuit. The feedback protection module is used to protect the MOSFET from overcurrent and short circuit. After the overcurrent and short circuit ends, the MOSFET resumes conduction after a delay. The signal input module is connected to the clamping module, and the clamping module is connected to the feedback protection module.

2. The self-recovery circuit for overcurrent protection of a MOSFET according to claim 1, characterized in that, The signal input module includes resistors R1, R3, R4, and R5, optocoupler Q2, diodes LED2 and LED3, resistors R9 and R15. One end of resistor R1 is connected to one end of resistor R3, one end of resistor R5, and interface XCOM. The other end of resistor R5 is connected to the negative terminal of diode LED2. The other end of resistor R3 is connected to the positive terminal of diode LED3. The positive terminal of diode LED2 is connected to the negative terminal of diode LED3. One end of resistor R4 is connected to the second end of optocoupler Q2 and interface X00. The other end of resistor R1 is connected to the other end of resistor R4 and the first end of optocoupler Q2. The fourth end of optocoupler Q2 is connected to a 24V voltage. The third end of optocoupler Q2 is connected to one end of resistor R9. The other end of resistor R9 is connected to one end of resistor R15 and the clamping module. The other end of resistor R15 is grounded.

3. The self-recovery circuit for overcurrent protection of a MOSFET according to claim 2, characterized in that, The model number of optocoupler Q1 is LV345T.

4. The self-recovery circuit for overcurrent protection of a MOSFET according to claim 1, characterized in that, The clamping module includes a resistor R11, a diode D32, and a diode D34. One end of the resistor R11 is connected to the signal input module, and the other end of the resistor R11 is connected to the negative terminal of the diode D32 and the feedback protection module. The positive terminal of the resistor D32 is connected to the positive terminal of the diode D34, and the negative terminal of the diode D34 is grounded.

5. The self-recovery circuit for overcurrent protection of a MOSFET according to claim 1, characterized in that, The feedback protection module includes diodes D1 and D3, capacitor C2, transistor Q100, resistor R100, capacitor C11, amplifier, capacitor C105, diode LED1, resistors R2, R13, and R16, diode D2, resistor R17, transistor Q3, resistor R8, resistor R12, MOSFET Q1. The gate of MOSFET Q1 is connected to the collector of transistor Q3, the anode of diode D1, the anode of diode D3, a clamping module, the cathode of diode D3 is connected to the signal input module, the cathode of diode D1 is connected to the output of the amplifier, the cathode of diode LED1, the anode of diode LED1 is connected to one end of resistor R2, the other end of resistor R2 is connected to a 24V voltage, the drain of MOSFET Q1 is connected to the load, and the source of MOSFET Q1 is connected to resistor R100. One end of resistor R8, one end of resistor R12, one end of resistor R17, the positive terminal of diode D2, the other end of resistor R8 is connected to the base of transistor Q3, the other end of resistor R12 is grounded, the emitter of transistor Q3 is grounded, the other end of resistor R17 is connected to the negative terminal of diode D2, the inverting input of amplifier, one end of capacitor C2, the collector of transistor Q100, the other end of capacitor C2 is grounded, the emitter of transistor Q100 is connected to 12V voltage, one end of resistor R100, the base of transistor Q100 is connected to the other end of resistor R100, one end of capacitor C11, the other end of capacitor C11 is connected to the negative terminal of diode LED1, the non-inverting input of amplifier is connected to one end of resistor R13, one end of resistor R16, the other end of resistor R13 is connected to 12V voltage, and the other end of resistor R16 is grounded.

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