MOS tube switch protection circuit

Abstract

The utility model discloses an MOS (Metal Oxide Semiconductor) tube switch protection circuit, which relates to the field of safety protection and comprises a time delay starting module, a time delay driving loop construction module, a time delay starting module, a time delay driving loop construction module and a time delay starting module, the loop construction module is used for constructing a direct-current output power supply loop when the direct-current input power supply is not under-voltage during working; when the direct-current input power supply is under-voltage, the direct-current output power supply loop is disconnected; the short-circuit protection module is used for controlling the delay starting module to restore the initial state when the direct-current output power supply is short-circuited during working; compared with the prior art, the utility model has the beneficial effects that both high voltage and low voltage can be applied, the input voltage range is wide, the voltage limitation of the traditional chip is broken through, and the high voltage scene of industrial equipment, new energy vehicles and the like can be adapted; a high-price chip is replaced by a discrete component combination scheme, so that the cost is reduced, and the market competitiveness of a product is remarkably improved; the cost performance is high, and the use requirements are met.

Description

Technical Field

[0001] This utility model relates to the field of safety protection, specifically a MOSFET switch protection circuit. Background Technology

[0002] In DC power supply systems, especially in industries such as automotive, communication equipment rooms, and medical power supplies, the downstream stage of a DC power supply is often connected to a variety of different loads. These loads may fail during operation, such as short circuits or overloads, which will have a serious impact on the entire power supply system and may even damage other normally functioning loads.

[0003] Currently, there are various circuits or chips on the market for protecting downstream loads of DC power supplies, but these products have some obvious drawbacks:

[0004] 1. High price: For example, the high price of protection chips such as RMJ50085 and LTC1153 increases the cost of the entire power supply system, which is not conducive to the market promotion and application of the products.

[0005] 2. Limited Input Voltage Range: Some integrated protection chips on the market typically have an input voltage range of less than 100V, making them unsuitable for high-voltage applications (greater than 100V). In modern electronic devices, high-voltage DC power supplies are increasingly widely used, thus this limitation significantly reduces the applicability of these protection chips.

[0006] In summary, existing circuits or chips for protecting downstream loads of DC power supplies have low cost-effectiveness (they are expensive or have limited applicability) and need improvement. Utility Model Content

[0007] The purpose of this invention is to provide a MOSFET switch protection circuit to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, this utility model provides the following technical solution:

[0009] A MOSFET switch protection circuit includes:

[0010] The delayed start module is used to enable the delayed drive circuit construction module to work after power-on;

[0011] The loop construction module is used to construct a DC output power circuit when the DC input power supply is not undervoltage, and to disconnect the DC output power circuit when the DC input power supply is undervoltage.

[0012] The short-circuit protection module is used to control the delayed start module to restore the initial state when a short circuit occurs at the DC output power supply during operation.

[0013] The delayed start module is connected to the loop construction module, the loop construction module is connected to the short circuit protection module, and the short circuit protection module is connected to the delayed start module.

[0014] As a further embodiment of this utility model: the delayed start module includes resistors R2, R3, and R6, capacitor C1, a three-terminal voltage regulator IC1, and diode D2. The negative terminal of diode D2 is connected to one end of resistor R3, the positive terminal of the DC input power supply +VIN, and the positive terminal of the DC output power supply +V0. The positive terminal of diode D2 is connected to one end of resistor R2. The other end of resistor R2 is connected to the negative terminal of the three-terminal voltage regulator IC1. The circuit construction module has the positive terminal of the three-terminal voltage regulator IC1 connected to the negative terminal of the DC input power supply -VIN. The reference terminal of the three-terminal voltage regulator IC1 is connected to the other end of resistor R3, one end of resistor R6, and one end of capacitor C1. The short-circuit protection module has the other end of resistor R6 connected to the other end of capacitor C1 and the negative terminal of the DC input power supply -VIN.

[0015] As a further embodiment of this utility model: the circuit construction module includes resistor R4, resistor R7, transistor Q1, resistor R1, resistor R5, diode D1, MOSFET M1, resistor R8, and capacitor C2. One end of resistor R4 is connected to the delay start module, and the other end of resistor R4 is connected to one end of resistor R7 and the base of transistor Q1. The other end of resistor R7 is connected to the negative terminal of the DC input power supply -VIN, the emitter of transistor Q1, one end of resistor R5, and the first terminal of MOSFET M1. The collector of transistor Q1 is connected to one end of resistor R1, the other end of resistor R5, the negative terminal of diode D1, and the second terminal of MOSFET M1. The other end of resistor R1 is connected to the positive terminal of the DC input power supply +VIN and the positive terminal of the DC output power supply +V0. The third terminal of MOSFET M1 is connected to one end of capacitor C2 and one end of resistor R8. The other end of capacitor C2 is connected to the other end of resistor R8, the negative terminal of the DC output power supply -V0, and the short-circuit protection module.

[0016] As a further improvement of this invention: the resistance value of resistor R8 is adjusted so that the voltage between the negative terminal of the DC output power supply -V0 and the negative terminal of the DC input power supply -VIN is less than 0.7V.

[0017] As a further embodiment of this utility model: the short-circuit protection module includes a resistor R9, a transistor Q2, and a transistor Q3. One end of the resistor R9 is connected to the negative terminal of the DC output power supply -V0, and the other end of the resistor R9 is connected to the base of the transistor Q2 and the collector of the transistor Q3. The collector of the transistor Q2 is connected to the delayed start module, the emitter of the transistor Q2 is connected to the negative terminal of the DC input power supply -VIN, the emitter of the transistor Q3 is connected to the negative terminal of the DC input power supply -VIN, and the base of the transistor Q3 is connected to the circuit construction module.

[0018] Compared with the prior art, the beneficial effects of this utility model are: this utility model can be applied to both high voltage (100V-400V) and low voltage (5V-100V), with a wide input voltage range, breaking through the voltage limitations of traditional chips, and can be adapted to high voltage scenarios such as industrial equipment and new energy vehicles; by replacing high-priced chips with discrete component combination solutions, the cost is reduced and the product's market competitiveness is significantly improved; it has a high cost performance and meets the needs of use. Attached Figure Description

[0019] Figure 1 This is a circuit diagram of a MOSFET switch protection circuit. Detailed Implementation

[0020] 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.

[0021] Please see Figure 1 A MOSFET switch protection circuit includes:

[0022] The delayed start module is used to enable the delayed drive circuit construction module to work after power-on;

[0023] The loop construction module is used to construct a DC output power circuit when the DC input power supply is not undervoltage, and to disconnect the DC output power circuit when the DC input power supply is undervoltage.

[0024] The short-circuit protection module is used to control the delayed start module to restore the initial state when a short circuit occurs at the DC output power supply during operation.

[0025] The delayed start module is connected to the loop construction module, the loop construction module is connected to the short circuit protection module, and the short circuit protection module is connected to the delayed start module.

[0026] In this embodiment: Please refer to Figure 1The delayed start module includes resistors R2, R3, and R6, capacitor C1, a three-terminal regulator IC1, and diode D2. The negative terminal of diode D2 is connected to one end of resistor R3, the positive terminal of the DC input power supply +VIN, and the positive terminal of the DC output power supply +V0. The positive terminal of diode D2 is connected to one end of resistor R2, and the other end of resistor R2 is connected to the negative terminal of the three-terminal regulator IC1. The circuit construction module connects the positive terminal of the three-terminal regulator IC1 to the negative terminal of the DC input power supply -VIN. The reference terminal of the three-terminal regulator IC1 is connected to the other end of resistor R3, one end of resistor R6, and one end of capacitor C1. The short-circuit protection module connects the other end of resistor R6 to the other end of capacitor C1 and the negative terminal of the DC input power supply -VIN.

[0027] After power-on, capacitor C1 is charged through resistor R3. When capacitor C1 is charged to 2.5V, the negative and positive terminals of the three-terminal regulator IC1 (model can be TL431) are turned on, and point A becomes low level. Therefore, point A is high level in the initial stage of power-on. Only after the negative and positive terminals of the three-terminal regulator IC1 are turned on will point A become low level to start the circuit construction module.

[0028] In this embodiment: Please refer to Figure 1 The circuit construction module includes resistor R4, resistor R7, transistor Q1, resistor R1, resistor R5, diode D1, MOSFET M1, resistor R8, and capacitor C2. One end of resistor R4 is connected to the delay start module, and the other end of resistor R4 is connected to one end of resistor R7 and the base of transistor Q1. The other end of resistor R7 is connected to the negative terminal of the DC input power supply -VIN, the emitter of transistor Q1, one end of resistor R5, and the first terminal of MOSFET M1. The collector of transistor Q1 is connected to one end of resistor R1, the other end of resistor R5, the negative terminal of diode D1, and the second terminal of MOSFET M1. The other end of resistor R1 is connected to the positive terminal of the DC input power supply +VIN and the positive terminal of the DC output power supply +V0. The third terminal of MOSFET M1 is connected to one end of capacitor C2 and one end of resistor R8. The other end of capacitor C2 is connected to the other end of resistor R8, the negative terminal of the DC output power supply -V0, and the short-circuit protection module.

[0029] The potential at point A is low. By adjusting the values ​​of resistors R4 and R7, V... A When *R7 / (R4+R7)<0.7V, transistor Q1 is not conducting. At this time, VIN*R5 / (R1+R5)>2.5V, MOSFET M1 is conducting, and there is voltage at the positive terminal +V0 of the DC output power supply. At this moment, there is also voltage at the negative terminal -V0 of the DC output power supply, and the load at the output terminal is powered on and works.

[0030] By setting the ratio of resistors R3 to R6, when VIN*R6 / (R3+R6) < 2.5V, the three-terminal regulator IC1 will not conduct, MOSFET Q1 will conduct, and MOSFET M1 will not conduct, thus achieving input undervoltage protection.

[0031] In this embodiment: Please refer to Figure 1 Adjust the resistance of resistor R8 so that the voltage between the negative terminal of the DC output power supply -V0 (common point C) and the negative terminal of the DC input power supply -VIN (common point D) is less than 0.7V.

[0032] In this embodiment: Please refer to Figure 1 The short-circuit protection module includes a resistor R9, a transistor Q2, and a transistor Q3. One end of the resistor R9 is connected to the negative terminal of the DC output power supply -V0, and the other end of the resistor R9 is connected to the base of transistor Q2 and the collector of transistor Q3. The collector of transistor Q2 is connected to the delayed start module, the emitter of transistor Q2 is connected to the negative terminal of the DC input power supply -VIN, the emitter of transistor Q3 is connected to the negative terminal of the DC input power supply -VIN, and the base of transistor Q3 is connected to the circuit construction module.

[0033] When the output load is normal, set the resistance value of resistor R8 so that V CD <0.7V, at this time transistor Q2 is not conducting. When the output is short-circuited, V CD When the voltage is greater than 0.7V, transistor Q2 conducts, pulling down the reference voltage of the three-terminal regulator IC1. The negative and anode terminals of IC1 are not conducting, and the voltage at the common point A is V. A Increase, V A *R7 / (R4+R7)>0.7V, transistors Q1 and Q3 are turned on. The conduction of transistor Q1 causes the gate (second terminal) pin of MOSFET M1 to be low, turning off MOSFET M1. Transistor Q3 then turns on, rapidly dissipating the voltage at the common point C, bringing it close to the voltage at the common point D, thus increasing V. CD When the voltage approaches 0V, transistor Q2 becomes non-conducting, the circuit returns to its initial state, and capacitor C1 is recharged. If the output load is still faulty, MOSFET M1 cycles between being on and off. If the output load fault is eliminated, MOSFET M1 is in the on state.

[0034] Since the three-terminal regulator IC1 can be a TL431 with a rated voltage of 36V, the three-terminal regulator IC1 can be made to operate within a safe range by adjusting the voltage regulation value of diode D2. By selecting appropriate parameters for transistor Q1 and MOSFET M1 according to the input voltage range, this circuit can be adapted to circuits with various voltage specifications and can provide protection in both high voltage (100V-400V) and low voltage (5V-100V).

[0035] The working principle of this utility model is as follows: the delayed start module is used to activate the delayed drive circuit construction module after power-on; when the circuit construction module is working, it constructs the DC output power circuit when the DC input power supply is not undervoltage; when the DC input power supply is undervoltage, it disconnects the DC output power circuit; when the short circuit protection module is working, it controls the delayed start module to return to the initial state when a short circuit occurs at the DC output power supply.

[0036] This invention utilizes a three-terminal voltage regulator IC1 (TL431) as a delay circuit to increase the delay accuracy of the delay circuit;

[0037] By using the base and emitter of transistor Q1 as a reference voltage and connecting a sampling resistor in series with MOSFET M1, the sampling voltage is increased, the turn-off current threshold of MOSFET M1 is set, the response speed is accelerated, and the safety of MOSFET M1 is improved.

[0038] 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.

[0039] 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 MOSFET switch protection circuit, characterized in that, The MOSFET switching protection circuit includes: The delayed start module is used to enable the delayed drive circuit construction module to work after power-on; The loop construction module is used to construct a DC output power circuit when the DC input power supply is not undervoltage, and to disconnect the DC output power circuit when the DC input power supply is undervoltage. The short-circuit protection module is used to control the delayed start module to restore the initial state when a short circuit occurs at the DC output power supply during operation. The delayed start module is connected to the loop construction module, the loop construction module is connected to the short circuit protection module, and the short circuit protection module is connected to the delayed start module.

2. The MOS switch protection circuit of claim 1, wherein, The delayed start module includes resistors R2, R3, and R6, capacitor C1, a three-terminal voltage regulator IC1, and diode D2. The negative terminal of diode D2 is connected to one end of resistor R3, the positive terminal of the DC input power supply +VIN, and the positive terminal of the DC output power supply +V0. The positive terminal of diode D2 is connected to one end of resistor R2, and the other end of resistor R2 is connected to the negative terminal of the three-terminal voltage regulator IC1. The circuit construction module connects the positive terminal of the three-terminal voltage regulator IC1 to the negative terminal of the DC input power supply -VIN. The reference terminal of the three-terminal voltage regulator IC1 is connected to the other end of resistor R3, one end of resistor R6, and one end of capacitor C1. The short-circuit protection module connects the other end of resistor R6 to the other end of capacitor C1 and the negative terminal of the DC input power supply -VIN.

3. The MOS switch protection circuit of claim 1, wherein, The circuit construction module includes resistor R4, resistor R7, transistor Q1, resistor R1, resistor R5, diode D1, MOSFET M1, resistor R8, and capacitor C2. One end of resistor R4 is connected to the delay start module, and the other end of resistor R4 is connected to one end of resistor R7 and the base of transistor Q1. The other end of resistor R7 is connected to the negative terminal of the DC input power supply -VIN, the emitter of transistor Q1, one end of resistor R5, and the first terminal of MOSFET M1. The collector of transistor Q1 is connected to one end of resistor R1, the other end of resistor R5, the cathode of diode D1, and the second terminal of MOSFET M1. The other end of resistor R1 is connected to the positive terminal of the DC input power supply +VIN and the positive terminal of the DC output power supply +V0. The third terminal of MOSFET M1 is connected to one end of capacitor C2 and one end of resistor R8. The other end of capacitor C2 is connected to the other end of resistor R8, the negative terminal of the DC output power supply -V0, and the short-circuit protection module.

4. The MOS switch protection circuit of claim 3, wherein, Adjust the resistance of resistor R8 so that the voltage between the negative terminal of the DC output power supply -V0 and the negative terminal of the DC input power supply -VIN is less than 0.7V.

5. The MOS switch protection circuit of claim 1, wherein, The short-circuit protection module includes resistor R9, transistor Q2, and transistor Q3. One end of resistor R9 is connected to the negative terminal of the DC output power supply -V0, and the other end of resistor R9 is connected to the base of transistor Q2 and the collector of transistor Q3. The collector of transistor Q2 is connected to the delayed start module, the emitter of transistor Q2 is connected to the negative terminal of the DC input power supply -VIN, the emitter of transistor Q3 is connected to the negative terminal of the DC input power supply -VIN, and the base of transistor Q3 is connected to the circuit construction module.

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