Protection circuit

Abstract

The utility model discloses a protection circuit, which is characterized in that a reverse connection prevention circuit is arranged to receive power supply voltage provided by an external power supply and output the power supply voltage to a booster circuit; and when the current flows back to the external power supply from the booster circuit, the external power supply is protected; the booster circuit receives the power supply voltage, converts the power supply voltage into working voltage and outputs the working voltage to the external equipment; the voltage stabilizing circuit stabilizes the power supply voltage output by the external power supply. When the external power supply is reversely connected, the situation that current flows back to the external power supply from a rear-end circuit is avoided, namely, the situation that the whole circuit is leaked is avoided, and the situation that the battery is damaged due to abnormal power consumption and accelerated battery aging is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit protection, and particularly relates to a protection circuit. Background Art

[0002] For some circuits powered by dry batteries or button batteries, there may be a situation where the battery is accidentally reversed, causing the current to flow back from the backend to the dry battery or button battery, resulting in leakage in the entire circuit, abnormal power consumption, and accelerating battery aging, thereby causing battery damage. Summary of the Utility Model

[0003] Based on this, it is necessary to propose a protection circuit for the above problems.

[0004] A protection circuit includes:

[0005] An anti-reverse connection circuit, with its input end connected to an external power supply and its output end connected to a boost circuit, for receiving the supply voltage provided by the external power supply and outputting the supply voltage to the boost circuit; and when the current flows back from the boost circuit to the external power supply, protecting the external power supply;

[0006] The boost circuit, with its output end connected to an external device, for receiving the supply voltage, converting the supply voltage into a working voltage, and outputting it to the external device;

[0007] A voltage stabilization circuit, with one end connected between the anti-reverse connection circuit and the boost circuit and the other end grounded, for stabilizing the supply voltage output by the external power supply.

[0008] In one embodiment, the protection circuit further includes:

[0009] A voltage division circuit, connected between the anti-reverse connection circuit and the boost circuit, for dividing the supply voltage output by the anti-reverse connection circuit and then outputting it to the boost circuit;

[0010] A filtering circuit, connected between the anti-reverse connection circuit and the boost circuit, for filtering the supply voltage.

[0011] In one embodiment, the anti-reverse connection circuit includes: a first diode, a first MOS transistor, and a second MOS transistor;

[0012] The source electrode of the first MOS transistor is connected to the external power supply, the drain electrode of the first MOS transistor is connected to the boost circuit, and the gate electrode of the first MOS transistor is connected to the drain electrode of the second MOS transistor;

[0013] The anode of the first diode is connected to the source of the first MOS transistor, and the cathode of the first diode is connected to the drain of the first MOS transistor;

[0014] The source of the second MOS transistor is connected to the boost circuit, and the gate of the second MOS transistor is grounded.

[0015] In one embodiment, the reverse connection prevention circuit further includes: a first resistor, a second resistor, and a third resistor;

[0016] One end of the first resistor is connected to the gate of the first MOS transistor, and the other end of the first resistor is connected to the drain of the second MOS transistor;

[0017] One end of the second resistor is connected to the source of the second MOS transistor, and the other end of the second resistor is connected to the boost circuit;

[0018] One end of the third resistor is connected to the gate of the second MOS transistor, and the other end of the third resistor is grounded.

[0019] In one embodiment, the voltage regulation circuit includes: a second diode and a third diode;

[0020] The cathode of the second diode is connected to the external power supply, and the anode of the second diode is connected to the anode of the third diode;

[0021] The cathode of the third diode is grounded.

[0022] In one embodiment, the voltage division circuit includes: a fourth resistor;

[0023] One end of the fourth resistor is connected to the drain of the first MOS transistor, and the other end of the fourth resistor is connected to the boost circuit.

[0024] In one embodiment, the filtering circuit includes: a first capacitor and a second capacitor;

[0025] One end of the first capacitor is connected to the drain of the first MOS transistor, and the other end of the first capacitor is grounded;

[0026] One end of the second capacitor is connected to the other end of the fourth resistor, and the other end of the second capacitor is grounded.

[0027] In one embodiment, the boost circuit includes: a boost chip;

[0028] The input end of the boost chip is connected to the output end of the reverse connection prevention circuit;

[0029] The output end of the boost chip is connected to the external device.

[0030] In one embodiment, the first MOS transistor is an NMOS transistor and the second MOS transistor is a PMOS transistor.

[0031] Implementing the embodiments of the present utility model will have the following beneficial effects:

[0032] This application provides a reverse connection protection circuit to receive the power supply voltage provided by an external power supply and output the power supply voltage to the boost circuit; and, when current flows back from the boost circuit to the external power supply, it protects the external power supply; the boost circuit receives the power supply voltage, converts the power supply voltage into a working voltage, and outputs it to the external device; the voltage stabilization circuit stabilizes the power supply voltage output by the external power supply. This ensures that when the external power supply is reversely connected, current will not flow back from the backend circuit to the external power supply, that is, the situation of the entire circuit leakage will not occur, avoiding abnormal power consumption and accelerating battery aging, which may cause battery damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0034] Among them:

[0035] Figure 1 is a structural block diagram of a protection circuit in one embodiment;

[0036] Figure 2 is a structural block diagram of a protection circuit in another embodiment;

[0037] Figure 3 is a circuit diagram of a protection circuit in one embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only some of the embodiments of the present utility model, rather than all of them. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.

[0039] For some circuits powered by dry batteries or button batteries, there may be a situation where the battery is accidentally reverse-connected, causing current to flow back from the backend to the dry battery or button battery, resulting in leakage in the entire circuit, abnormal power consumption, and accelerated battery aging, which may further damage the battery. To solve the above technical problems, the present application provides a protection circuit, as Figure 1 shown, including: an anti-reverse connection circuit 10, a boost circuit 20, and a voltage stabilization circuit 30. Among them, the input end of the anti-reverse connection circuit 10 is connected to an external power supply, and the output end is connected to the boost circuit 20, which is used to receive the supply voltage provided by the external power supply and output the supply voltage to the boost circuit 20; and, when current flows back from the boost circuit 20 to the external power supply, it protects the external power supply; the output end of the boost circuit 20 is connected to an external device, which is used to receive the supply voltage, convert the supply voltage into a working voltage, and output it to the external device; one end of the voltage stabilization circuit 30 is connected between the anti-reverse connection circuit 10 and the boost circuit 20, and the other end is grounded, which is used to stabilize the supply voltage output by the external power supply. The present application receives the supply voltage provided by the external power supply through the anti-reverse connection circuit and outputs the supply voltage to the boost circuit; and, when current flows back from the boost circuit to the external power supply, it protects the external power supply; the boost circuit receives the supply voltage, converts the supply voltage into a working voltage, and outputs it to the external device; the voltage stabilization circuit stabilizes the supply voltage output by the external power supply. When the external power supply is reverse-connected, current will not flow back from the backend circuit to the external power supply, that is, there will be no leakage in the entire circuit, avoiding abnormal power consumption and accelerated battery aging, which may further damage the battery.

[0040] In one embodiment, as Figure 2 shown, the protection circuit further includes: a voltage dividing circuit 40 and a filtering circuit 50. Among them, the voltage dividing circuit 40 is connected between the anti-reverse connection circuit 10 and the boost circuit 20, and is used to divide the supply voltage output by the anti-reverse connection circuit 10 and then output it to the boost circuit 20; the filtering circuit 50 is connected between the anti-reverse connection circuit 10 and the boost circuit 20, and is used to filter the supply voltage.

[0041] In one embodiment, as Figure 3As shown, the reverse connection prevention circuit 10 includes: a first diode D3, a first MOS transistor Q1, and a second MOS transistor Q2; wherein, the source of the first MOS transistor Q1 is connected to the external power supply, the drain of the first MOS transistor Q1 is connected to the boost circuit 20, and the gate of the first MOS transistor Q1 is connected to the drain of the second MOS transistor Q2; the anode of the first diode D3 is connected to the source of the first MOS transistor Q1, and the cathode of the first diode D3 is connected to the drain of the first MOS transistor Q1; the source of the second MOS transistor Q2 is connected to the boost circuit 20, and the gate of the second MOS transistor Q2 is grounded.

[0042] In one embodiment, as Figure 3 As shown, the reverse connection prevention circuit 10 further includes: a first resistor R2, a second resistor R3, and a third resistor R5; wherein, one end of the first resistor R2 is connected to the gate of the first MOS transistor Q1, and the other end of the first resistor R2 is connected to the drain of the second MOS transistor Q2; one end of the second resistor R3 is connected to the source of the second MOS transistor Q2, and the other end of the second resistor R3 is connected to the boost circuit 20; one end of the third resistor R5 is connected to the gate of the second MOS transistor Q2, and the other end of the third resistor R5 is grounded.

[0043] In one embodiment, as Figure 3 As shown, the voltage stabilization circuit 30 includes: a second diode D1 and a third diode D2; wherein, the cathode of the second diode D1 is connected to the external power supply, the anode of the second diode D1 is connected to the anode of the third diode D2; the cathode of the third diode D2 is grounded.

[0044] In one embodiment, as Figure 3 As shown, the voltage division circuit 50 includes: a fourth resistor R4; wherein, one end of the fourth resistor R4 is connected to the drain of the first MOS transistor Q1, and the other end of the fourth resistor R4 is connected to the boost circuit 20.

[0045] In one embodiment, as Figure 3 As shown, the filter circuit 40 includes: a first capacitor C1 and a second capacitor C2; wherein, one end of the first capacitor C1 is connected to the drain of the first MOS transistor Q1, and the other end of the first capacitor C1 is grounded; one end of the second capacitor C2 is connected to the other end of the fourth resistor R4, and the other end of the second capacitor C2 is grounded.

[0046] In one embodiment, as Figure 3As shown, the boost circuit 20 includes: a boost chip U1; wherein, the input terminal VIN of the boost chip U1 is connected to the output terminal of the reverse connection prevention circuit 10; the output terminal SW of the boost chip U1 is connected to the external device.

[0047] In one embodiment, the first MOS transistor Q1 is an NMOS transistor, and the second MOS transistor Q2 is a PMOS transistor.

[0048] The working principle of this application is as follows:

[0049] When connected correctly, the source pin voltage of the first MOS transistor Q1 is 1.4V, and the gate pin voltage is 0. The first MOS transistor Q1 is not turned on. The current reaches the backend boost chip U1 through the first diode D3. The boost chip U1 outputs a voltage of 2.8V. At this time, the source pin voltage of the second MOS transistor Q2 is 2.8V, and the gate pin voltage is 0. The second MOS transistor Q2 is turned on. At this time, the gate pin voltage corresponding to the first MOS transistor Q1 is 2.8V, Vgs is 1.4V, and the first MOS transistor Q1 is turned on.

[0050] When reverse-connected, when the current flows back from the boost circuit to the external power supply, there will be a small voltage at the source pin of the second MOS transistor Q2. At this time, the gate pin voltage is greater than the source pin voltage, so the second MOS transistor Q2 cannot be turned on, and the leakage current cannot flow to the external power supply.

[0051] The above-disclosed are only the preferred embodiments of the present invention. Of course, the scope of the rights of the present invention cannot be limited by this. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A protection circuit, characterized in that: include: An anti-reverse connection circuit, the input end of which is connected to an external power supply, and the output end of which is connected to a boost circuit, for receiving a supply voltage provided by the external power supply and outputting the supply voltage to the boost circuit; and, when current flows back from the boost circuit to the external power supply, protecting the external power supply; The boost circuit, whose output end is connected to an external device, is used to receive the supply voltage, convert the supply voltage into a working voltage, and output it to the external device; A voltage stabilizing circuit has one end connected between the anti-reverse connection circuit and the boost circuit and the other end grounded, and is used to stabilize the supply voltage output by the external power supply.

2. The protection circuit according to claim 1, characterized in that: Also includes: A voltage divider circuit, connected between the anti-reverse connection circuit and the boost circuit, for dividing the supply voltage output by the anti-reverse connection circuit and outputting the voltage to the boost circuit; The filter circuit is connected between the anti-reverse connection circuit and the boost circuit, and is used for filtering the supply voltage.

3. The protection circuit according to claim 2, characterized in that: The anti-reverse connection circuit comprises: a first diode, a first MOS transistor and a second MOS transistor; The source of the first MOS tube is connected to the external power supply, the drain of the first MOS tube is connected to the boost circuit, and the gate of the first MOS tube is connected to the drain of the second MOS tube; The anode of the first diode is connected to the source of the first MOS transistor, and the cathode of the first diode is connected to the drain of the first MOS transistor; The source of the second MOS tube is connected to the boost circuit, and the gate of the second MOS tube is grounded.

4. The protection circuit according to claim 3, characterized in that: The anti-reverse connection circuit also includes: a first resistor, a second resistor and a third resistor; One end of the first resistor is connected to the gate of the first MOS transistor, and the other end of the first resistor is connected to the drain of the second MOS transistor; One end of the second resistor is connected to the source of the second MOS tube, and the other end of the second resistor is connected to the boost circuit; One end of the third resistor is connected to the gate of the second MOS transistor, and the other end of the third resistor is grounded.

5. The protection circuit according to claim 1, characterized in that: The voltage stabilizing circuit comprises: a second diode and a third diode; The cathode of the second diode is connected to the external power supply, and the anode of the second diode is connected to the anode of the third diode; A cathode of the third diode is grounded.

6. The protection circuit according to claim 3, characterized in that: The voltage divider circuit comprises: a fourth resistor; One end of the fourth resistor is connected to the drain of the first MOS tube, and the other end of the fourth resistor is connected to the boost circuit.

7. The protection circuit according to claim 6, characterized in that: The filter circuit comprises: a first capacitor and a second capacitor; One end of the first capacitor is connected to the drain of the first MOS transistor, and the other end of the first capacitor is grounded; One end of the second capacitor is connected to the other end of the fourth resistor, and the other end of the second capacitor is grounded.

8. The protection circuit according to claim 1, characterized in that: The boost circuit comprises: a boost chip; The input end of the boost chip is connected to the output end of the anti-reverse connection circuit; The output end of the boost chip is connected to the external device.

9. The protection circuit according to claim 3, characterized in that: The first MOS tube is an NMOS tube, and the second MOS tube is a PMOS tube.

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