Input end power supply protection circuit for switch

Abstract

The invention relates to the technical field of interactive machine power supply control, in particular to an input end power supply protection circuit for a switch, which comprises an input end, an anti-reverse connection control unit, an anti-overvoltage control unit and a slow start control unit, the input end is provided with a positive electrode connecting end and a negative electrode connecting end; the anti-reverse connection control unit comprises a switch tube Q1, and the negative electrode connecting end is connected to a load through the switch tube Q1; a grounding end PGND is connected between the negative electrode connecting end and the switch tube Q1; the anti-overvoltage control unit comprises a voltage stabilizing diode D4; the slow start control unit comprises a switch tube Q2, a switch tube Q3, a capacitor C2, a capacitor C4, a resistor R4, a resistor R5, a resistor R7 and a voltage stabilizing diode D1. Load damage caused by manual mistaken reverse connection of the energy storage battery can be prevented, the problem of load damage caused by power supply fluctuation caused by high load and large current when the mobile equipment is started can be solved, the structure is novel, and the design is ingenious.

Description

Technical Field

[0001] The present invention relates to the technical field of interactive machine power supply control, in particular to an input end power supply protection circuit for a switch. Background Art

[0002] Nowadays, there are many types of switches on the market, but they are basically placed in a fixed position indoors and powered by 220V AC. This power supply method is not suitable for use on mobile devices, and energy storage batteries are required. In order to prevent the power polarity of the power supply from being reversed when powered by energy storage batteries, which may damage the device, it is necessary to introduce a small impedance, safe and reliable anti-reverse connection circuit. At the same time, when the mobile device is started, the output voltage of the energy storage battery may be extremely unstable due to the large current. At this time, it is necessary to introduce an anti-overvoltage and slow start circuit at the same time to protect the device from being damaged by the impact current at startup; the current traditional power supply control circuits are three independent circuits, namely, the anti-reverse connection circuit, the anti-overvoltage circuit and the slow start circuit are independent; but the combination of the three circuits is redundant and complex. Summary of the invention

[0003] In view of the problems of the prior art, the present invention provides an input power supply protection circuit for a switch, which can prevent load damage caused by artificial reverse connection of energy storage batteries and solve the problem of load damage caused by power supply fluctuations due to high loads and large currents when mobile devices are started. The invention has a novel structure and ingenious design.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides an input end power supply protection circuit for a switch, which comprises an input end, an anti-reverse connection control unit, an anti-overvoltage control unit and a soft start control unit;

[0006] The input end is provided with a positive connection end and a negative connection end; the anti-reverse connection control unit includes a switch tube Q1, and the negative connection end is connected to the load through the switch tube Q1; a ground terminal PGND is connected between the negative connection end and the switch tube Q1;

[0007] The overvoltage protection control unit includes a voltage stabilizing diode D4;

[0008] The slow start control unit includes a switch tube Q2, a switch tube Q3, a capacitor C2, a capacitor C4, a resistor R4, a resistor R5, a resistor R7 and a voltage regulator diode D1, wherein the positive electrode connection end is connected to the cathode of the voltage regulator diode D1, the gate of the switch tube Q1, one end of the capacitor C2, the source of the switch tube Q2 and the emitter of the transistor Q3, the positive electrode of the voltage regulator diode D1, the other end of the capacitor C2 and the source of the switch tube Q1 are grounded respectively, the drain of the switch tube Q2 is connected to the load, the collector of the transistor Q3 is connected to one end of the resistor R7 and one end of the resistor R5 respectively, the other end of the resistor R5 is connected to the gate of the switch tube Q2, the other end of the resistor R7 is grounded, the capacitor C4 is connected between the base of the transistor Q3 and the collector of the transistor Q3, the base of the transistor Q3 is connected to one end of the resistor R4, the other end of the resistor R4 is connected to the negative electrode of the voltage regulator diode D4, and the anode of the voltage regulator diode D4 is connected to the ground terminal PGND.

[0009] Among them, the input end also includes an inductor L1, an inductor L2, a resistor R1 and a capacitor C1, one end of the inductor L1 is connected to one end of the resistor R1 and the source of the switch tube Q2, the other end of the resistor R1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to the drain of the switch tube Q1.

[0010] The slow-start combination circuit further includes a transient voltage suppressor D2, and two ends of the transient voltage suppressor D2 are respectively connected between the positive electrode connection end and the negative electrode connection end.

[0011] Among them, the slow start control unit also includes a resistor R3, a capacitor C3 and a Zener diode D5, one end of the capacitor C3, one end of the resistor R3 and the cathode of the Zener diode D5 are connected to the positive electrode connection end, the other end of the resistor R3 is connected to the cathode of the Zener diode D4, and the other end of the capacitor C3 and the anode of the Zener diode D5 are connected to the gate of the switch tube Q2.

[0012] Wherein, the breakdown voltage of the voltage stabilizing diode D5 is 9.1V.

[0013] Wherein, the breakdown voltage of the voltage stabilizing diode D4 is 12V.

[0014] Wherein, the breakdown voltage of the voltage stabilizing diode D1 is 9.1V.

[0015] Among them, capacitor C4 is 0.1UF.

[0016] Beneficial effects of the present invention:

[0017] The present invention can prevent load damage caused by artificial reverse connection of energy storage batteries, and can solve the problem of load damage caused by power supply fluctuations caused by high loads and large currents when mobile devices are started. It has a novel structure and ingenious design. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a circuit diagram of an input power supply protection circuit for a switch. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with the embodiments and drawings, and the contents mentioned in the embodiments are not intended to limit the present invention. The present invention is described in detail below in conjunction with the drawings.

[0020] An input end power supply protection circuit for a switch, comprising an input end, an anti-reverse connection control unit, an anti-overvoltage control unit and a slow start control unit;

[0021] The input end is provided with a positive connection end and a negative connection end; the anti-reverse connection control unit includes a switch tube Q1, and the negative connection end is connected to the load through the switch tube Q1; a ground terminal PGND is connected between the negative connection end and the switch tube Q1;

[0022] The overvoltage protection control unit includes a voltage stabilizing diode D4;

[0023] The slow start control unit includes a switch tube Q2, a switch tube Q3, a capacitor C2, a capacitor C4, a resistor R4, a resistor R5, a resistor R7 and a voltage regulator diode D1, wherein the positive electrode connection end is connected to the cathode of the voltage regulator diode D1, the gate of the switch tube Q1, one end of the capacitor C2, the source of the switch tube Q2 and the emitter of the transistor Q3, the positive electrode of the voltage regulator diode D1, the other end of the capacitor C2 and the source of the switch tube Q1 are grounded respectively, the drain of the switch tube Q2 is connected to the load, and the collector of the transistor Q3 is connected to one end of the resistor R7 and one end of the resistor R5 respectively, The other end of the resistor R5 is connected to the gate of the switch tube Q2, the other end of the resistor R7 is grounded, the capacitor C4 is connected between the base of the transistor Q3 and the collector of the transistor Q3, the base of the transistor Q3 is connected to one end of the resistor R4, the other end of the resistor R4 is connected to the cathode of the Zener diode D4, and the anode of the Zener diode D4 is connected to the ground terminal PGND; the breakdown voltage of the Zener diode D5 is 9.1V; the breakdown voltage of the Zener diode D4 is 12V; the breakdown voltage of the Zener diode D1 is 9.1V; the capacitor C4 is 0.1UF.

[0024] In the embodiment of the present application, the slow start control unit further includes a resistor R3, a capacitor C3 and a voltage stabilizing diode D5, one end of the capacitor C3, one end of the resistor R3 and the cathode of the voltage stabilizing diode D5 are connected to the positive electrode connection end, the other end of the resistor R3 is connected to the cathode of the voltage stabilizing diode D4, and the other end of the capacitor C3 and the positive electrode of the voltage stabilizing diode D5 are connected to the gate of the switch tube Q2. Specifically, under the above setting, the capacitor C3 is a gate-source capacitor, which is used to cooperate with the switch tube Q2 (PMOS) to stabilize its state; the resistor R5 is a current limiting resistor, which is used to protect the switch tube Q2 (PMOS); when VIN>UZ+0.7V, the transistor Q3 is turned on and the switch tube Q2 (PMOS) is turned off.

[0025] Specifically, when the embodiment of the present application is working, after the input power supply 12V is correctly connected from the input end with polarity, since the voltage stabilization value of the voltage stabilizing diode D4 is set to 12V, D4 (12V) will not reversely break down at the moment of power-on, and due to the body diode effect of the switch tube Q2, the current charges the capacitor C4 (0.1UF) through the EB pole of the transistor Q3 (PNP), the capacitor C4, and the resistor R7. At this time, the charging current is the largest, and the Vce of the transistor Q3 is approximately equal to 0, that is, the Vgs of the switch tube Q2 (PMOS) is approximately equal to 0; the switch tube Q2 (PMOS) obviously cannot be turned on, and the subsequent load is disconnected and cannot work. ; As the charging of capacitor C4 is completed, the charging current decreases, and the Vgs of the switch tube Q2 begins to be determined by the Zener diode D5 (9.1V). At this time, because the input 12V power supply is higher than 9.1V, the Zener diode D5 breaks down, and Vgs=9.1V. Obviously, at this time, Vgs (gate-source voltage) is greater than Vgsth (threshold voltage), and the switch tube Q2 (PMOS) begins to turn on. The current passes through the switch tube Q2 (PMOS) through the load to the switch tube Q1 (NMOS). Due to the body diode effect of the switch tube Q1 (NMOS), the ground loop current is turned on through the body diode of the switch tube Q1 (NMOS).

[0026] At this time, the Vgs (gate-source voltage) of the switch tube Q1 (NMOS) is also greater than the Vgsth (threshold voltage), the switch tube Q1 (NMOS) is turned on, and the power supply returns to the ground terminal PGND through the switch tube Q1 (NMOS), and returns to the negative electrode of the power supply (negative electrode connection terminal) after passing through the inductor L2 to form a closed loop. The load is powered normally and the equipment works normally; from the operation of the circuit of the embodiment of the present application, it can be seen that the switch tube Q2 (PMOS) is turned on after the capacitor C4 is charged, and the curvature of the charging of the capacitor C4 will affect the turn-on time of the switch tube Q2 (PMOS), and changing the capacity of the capacitor C4 will affect the charging curvature, so the circuit can achieve the purpose of slow start; capacitor C3 is a gate-source capacitor, which is used to cooperate with the switch tube Q2 (PMOS) to work and stabilize its state; resistor R5 is a current limiting resistor, which is used to protect the switch tube Q2 (PMOS).

[0027] When the input power 12V is connected with reverse polarity from the input end, the power flows from the ground end PGND to the load. At this time, the body diode of the switch tube Q1 (NMOS) is not conducting, and the switch tube Vgs (gate-source voltage) does not meet the requirements. The switch tube Q1 (NMOS) is not conducting, there is no current loop in the circuit, and the load circuit breaker does not work, thereby achieving the purpose of protecting the load; only when the power supply is connected normally, after the 12V power supply flows through the load, can the current flow through the source (S) of the switch tube Q1 (NMOS) to the drain (D) and return to the ground end PGND due to the diode effect of the MOS tube, forming a complete loop; it can be seen from the circuit operation that when the input power is reversed, this circuit cannot work, thereby playing a role in preventing reverse connection.

[0028] Because the Vgs voltage of the switch tube Q1 cannot exceed the maximum rated value of the switch tube Q1 (NMOS), a voltage regulator diode D1 (9.1V) needs to be connected to the S pole to stabilize the voltage within the maximum rated value of the switch tube Q1 (NMOS), and a capacitor is connected as a buffer to protect the MOS tube during startup.

[0029] When the input power supply 12V is connected by overvoltage at the input end, Vin>Vbr at this time, the Zener diode D4 is reversely broken down, the voltage on it is Vbr, and the current flows back to the ground terminal PGND through the transistor Q3 (PNP transistor) EB pole, resistor R4, and Zener diode D4; the transistor Q3 (PNP transistor) is turned on, and the Vce of the transistor Q3 is approximately equal to 0, that is, the Vgs of the switch tube Q2 (PMOS) is approximately equal to 0; the switch tube Q2 (PMOS) is not turned on, and the subsequent load is disconnected and does not work, that is, the role of protecting the load circuit is achieved; when VIN>12.7V, the Zener diode D4 is reversely broken down, the transistor Q3 is turned on, and the switch Q2 (PMOS) is turned off to protect the circuit.

[0030] The embodiments of the present application can prevent load damage caused by mistaken reverse connection of energy storage batteries, and can solve the problem of load damage caused by power supply fluctuations due to high loads and large currents when mobile devices are started. The structure is novel and the design is ingenious.

[0031] In the embodiment of the present application, the input end also includes an inductor L1, an inductor L2, a resistor R1 and a capacitor C1, one end of the inductor L1 is connected to one end of the resistor R1 and the source of the switch tube Q2, the other end of the resistor R1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to the drain of the switch tube Q1. Specifically, under the above settings, when the input power supply 12V is correctly connected from the positive connection end of the input end, it will first be filtered by the inductor L1, the resistor R1, and the capacitor C1. Because the voltage stabilization value of the voltage stabilizing diode D4 is set to 12V, the voltage stabilizing diode D4 (12V) will not reversely break down at the moment of power on, and due to the body diode effect of the switch tube Q2, the current charges the capacitor C4 (0.1UF) through the EB pole of the transistor Q3 (PNP), the capacitor C4, and the resistor R7.

[0032] In the embodiment of the present application, the slow-start combination circuit further includes a transient voltage suppressor D2, and the two ends of the transient voltage suppressor D2 are respectively connected between the positive connection terminal and the negative connection terminal. Preferably, the model of the transient voltage suppressor D2 is CP0640SC, which can provide a fast response time to conduct and shunt harmful transient currents, thereby protecting the slow-start combination circuit of the present application.

[0033] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention is disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments according to the technology of the present invention are within the scope of the technical solution of the present invention without departing from the content of the technical solution of the present invention.

Claims

1. A power supply protection circuit for the input end of a switch, characterized in that: It includes an input terminal, an anti-reverse connection control unit, an anti-overvoltage control unit and a slow start control unit; The input end is provided with a positive connection end and a negative connection end; the anti-reverse connection control unit includes a switch tube Q1, and the negative connection end is connected to the load through the switch tube Q1; a ground terminal PGND is connected between the negative connection end and the switch tube Q1; The overvoltage protection control unit includes a voltage stabilizing diode D4; The slow start control unit includes a switch tube Q2, a switch tube Q3, a capacitor C2, a capacitor C4, a resistor R4, a resistor R5, a resistor R7 and a voltage regulator diode D1, wherein the positive electrode connection end is connected to the cathode of the voltage regulator diode D1, the gate of the switch tube Q1, one end of the capacitor C2, the source of the switch tube Q2 and the emitter of the transistor Q3, the positive electrode of the voltage regulator diode D1, the other end of the capacitor C2 and the source of the switch tube Q1 are grounded respectively, the drain of the switch tube Q2 is connected to the load, the collector of the transistor Q3 is connected to one end of the resistor R7 and one end of the resistor R5 respectively, the other end of the resistor R5 is connected to the gate of the switch tube Q2, the other end of the resistor R7 is grounded, the capacitor C4 is connected between the base of the transistor Q3 and the collector of the transistor Q3, the base of the transistor Q3 is connected to one end of the resistor R4, the other end of the resistor R4 is connected to the negative electrode of the voltage regulator diode D4, and the anode of the voltage regulator diode D4 is connected to the ground terminal PGND.

2. The input power supply protection circuit for a switch according to claim 1, characterized in that: The input end also includes an inductor L1, an inductor L2, a resistor R1 and a capacitor C1. One end of the inductor L1 is connected to one end of the resistor R1 and the source of the switch tube Q2. The other end of the resistor R1 is connected to one end of the capacitor C1. The other end of the capacitor C1 is connected to the drain of the switch tube Q1.

3. The input power supply protection circuit for a switch according to claim 1, characterized in that: The slow-start combination circuit further includes a transient voltage suppressor D2, and two ends of the transient voltage suppressor D2 are respectively connected between the positive electrode connection end and the negative electrode connection end.

4. The input power supply protection circuit for a switch according to claim 1, characterized in that: The soft start control unit also includes a resistor R3, a capacitor C3 and a zener diode D5, one end of the capacitor C3, one end of the resistor R3 and the cathode of the zener diode D5 are connected to the positive electrode connection end, the other end of the resistor R3 is connected to the cathode of the zener diode D4, and the other end of the capacitor C3 and the anode of the zener diode D5 are connected to the gate of the switch tube Q2.

5. The input power supply protection circuit for a switch according to claim 4, characterized in that: The breakdown voltage of the voltage stabilizing diode D5 is 9.1V.

6. The input power supply protection circuit for a switch according to claim 1, characterized in that: The breakdown voltage of the voltage stabilizing diode D4 is 12V.

7. The input power supply protection circuit for a switch according to claim 1, characterized in that: The breakdown voltage of the voltage stabilizing diode D1 is 9.1V.

8. The input power supply protection circuit for a switch according to claim 1, characterized in that: Capacitor C4 is 0.1UF.

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