A power protection circuit

Abstract

The utility model provides a kind of power supply protection circuit, its input power supply charges through switch control circuit to battery, whether the battery is reversed by battery connection line judgment circuit judges, once battery is reversed, then disconnect switch control circuit, input power supply stops to supply power to battery, ensure circuit safety.Simultaneously use zener diode V3 as the protection device between the gate-source of field effect transistor T1, once the operating voltage of battery exceeds the gate-source voltage range of field effect transistor T1, then zener diode V3 is turned on, effectively protects field effect transistor T1, reduces damage probability, so that the present application is applicable to more application scenarios.Simultaneously, the switching voltage of field effect transistor T1 uses input voltage to control switch, the voltage value of input power supply is stable, effectively avoids the problem that the MOS tube internal resistance increases and is damaged when MOS tube switch is not fully turned on.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit technology, specifically to a power supply protection circuit. Background Technology

[0002] Some devices, such as emergency broadcast systems and streetlights, require continuous power supply to maintain operation. Common input power sources include mains power, wind power, or solar panels, which then charge batteries via a conversion circuit. However, there's a certain probability of reverse wiring when connecting batteries to the circuit, potentially damaging the equipment. Furthermore, if a battery enters a sleep state due to low charge, it usually requires manual activation. These issues limit the application scenarios for batteries. Utility Model Content

[0003] To address the design flaws in existing power supply protection circuits that limit their application scenarios and require manual wake-up when entering sleep mode due to low battery, this invention provides a power supply protection circuit that prevents reverse connection of the battery, automatically wakes the battery, and automatically charges it. Simultaneously, it effectively protects circuit components, reduces the probability of component damage during use, improves circuit safety, and ensures that this solution can be applied to more scenarios.

[0004] The technical solution of this utility model is as follows: a power supply protection circuit, which includes: an input power supply and a storage battery, wherein the input power supply is connected to the circuit based on a power interface J1 and the storage battery is connected to the circuit based on a storage battery interface J2, characterized in that it further includes: a storage battery connection judgment circuit and a switch control circuit. The input power supply charges the battery through the switch control circuit; The battery connection judgment circuit is used to determine whether the battery is reversed. If the battery is not reversed, the switch control circuit is normally open, and the input power supply charges the battery through the switch control circuit. If the battery is reversed, the switch control circuit is turned off through the battery connection judgment circuit, and the input power supply stops charging the battery. The switching control circuit includes: a Zener diode V3, a transistor Q1, a resistor R2, a resistor R4, a resistor R5, and a field-effect transistor T1; the field-effect transistor T1 is a PMOS transistor. The negative terminal of the Zener diode V3, one end of the resistor R2, and the source of the field-effect transistor T1 are connected to the input power supply. The positive terminal of the Zener diode V3 is connected to the other end of the resistor R2, the gate of the field-effect transistor T1, and one end of the resistor R4. The other end of the resistor R4 is connected to the collector of the transistor Q1. The emitter of the transistor Q1 is grounded. The base of the transistor Q1 is connected to one end of the resistor R5. The drain of the field-effect transistor T1 is connected to the negative terminal of the diode V2 and the battery interface J2.

[0005] Its further features are: The input power supply is connected to the battery connection judgment circuit and the switch control circuit via diode V1; The battery connection determination circuit includes: resistor R1, resistor R3, diode V2, diode V4, comparator U1, resistor R6, resistor R7, and resistor R8. One end of resistor R1 is connected to the input power supply, and the other end of resistor R1 is connected to one end of resistor R3. The negative terminal of diode V2 is connected to the battery charging interface J2, and the other end of resistor R3 is connected to the negative terminal of diode V4. The positive terminal of diode V4 is grounded. The negative input terminal of comparator U1 is connected to the negative terminal of diode V4, and the positive input terminal of comparator U1 is connected to one end of resistor R7, one end of resistor R6, and one end of resistor R8. The other end of resistor R8 is grounded, and the other end of resistor R7 is connected to the reference voltage Vref. The output terminal of comparator U1 is connected to the other end of resistor R6. It also includes: steady-state circuits; The steady-state circuit includes: a steady-state device U2; the output terminal of the steady-state device U2 is connected to the other end of the resistor R5, and the input terminal of the steady-state device U2 is connected to the output terminal of the comparator U1.

[0006] This application provides a power supply protection circuit. The input power supply charges the battery through a switch control circuit. A battery connection detection circuit determines whether the battery is reverse-connected. If the battery is reverse-connected, the switch control circuit is disconnected, and the input power supply stops supplying power to the battery, ensuring circuit safety. This application uses a Zener diode V3 as a protection device between the gate and source of a field-effect transistor (FET) T1. If the battery's operating voltage exceeds the gate-source voltage range of FET T1, the Zener diode V3 conducts, effectively protecting FET T1 and reducing the probability of damage, making this application applicable to more application scenarios. Furthermore, this application uses the input voltage to control the switching voltage of FET T1, ensuring a stable input power supply voltage and effectively preventing damage caused by increased internal resistance of the MOSFET when it is not fully turned on. The battery connection detection circuit in this application determines whether the battery is reverse-connected and also has a battery wake-up function, ensuring greater practicality. The circuit structure of this application is simple. The judgment process of the battery connection judgment circuit is implemented based on the circuit hardware. The entire circuit does not require the use of a control chip or software programming control. It has low cost, high security, and is suitable for more application scenarios. Attached Figure Description

[0007] Figure 1 This is a circuit diagram of the power supply protection circuit in this application; Figure 2 This is a block diagram of the power supply protection circuit in this application. Detailed Implementation

[0008] like Figures 1-2 As shown, this application includes a power supply protection circuit, comprising: an input voltage, a battery, a battery connection determination circuit, a switch control circuit, and a steady-state circuit. The input power supply is connected to the circuit via power interface J1, and the battery is connected to the circuit via battery interface J2.

[0009] In this application, the input voltage charges the battery via a switch control circuit.

[0010] The switching control circuit includes: a Zener diode V3, a transistor Q1, resistors R2, R4, and R5, and a field-effect transistor T1; the field-effect transistor T1 is a PMOS transistor; the transistor Q1 is an NPN transistor; the cathode of the Zener diode V3, one end of resistor R2, and the source of the field-effect transistor T1 are connected to the cathode of the diode V1; the anode of the Zener diode V3 is connected to the other end of resistor R2, the gate of the field-effect transistor T1, and one end of resistor R4; the other end of R4 is connected to the collector of the transistor Q1; the emitter of the transistor Q1 is grounded; the base of the transistor Q1 is connected to one end of resistor R5; and the drain of the field-effect transistor T1 is connected to the cathode of the diode V2 and the battery interface J2.

[0011] In the switching control circuit, MOSFET T1 acts as a switching device. When the battery is correctly connected, MOSFET T1 is normally open. The input power supply is connected to the battery connection judgment circuit and the switching control circuit via diode V1; the input voltage interface J1 is connected to the positive terminal of diode V1. The input power supply charges the battery in battery interface J2 via diode V1, the source and drain of MOSFET T1. The input voltage of MOSFET T1 is divided by resistors R2 and R4 and forms a stable switching control circuit with the Zener diode V3. Zener diode V3 is used to prevent the MOSFET from burning out when the input voltage is too high, ensuring circuit safety. In specific applications, the forward voltage of Zener diode V3 is 10V. Once the voltage difference between the gate and source of MOSFET T1 exceeds 10V, Zener diode V3 conducts.

[0012] The technical solution of this application enables the input voltage to charge the battery. To ensure that reverse connection of the battery does not damage the components, a battery connection detection circuit is also included. This circuit determines whether the battery is reverse-connected. If the battery is not reverse-connected, the input power supply charges the battery through the switch control circuit. If the battery is reverse-connected, the switch control circuit is turned off, stopping the charging process. The circuit automatically shuts off when the battery discharges below the protection voltage. This circuit can also be used to wake up the battery and begin charging.

[0013] The battery connection detection circuit includes: resistors R1 and R3, diodes V2 and V4, comparator U1, resistors R6, R7, and R8. One end of resistor R1 is connected to the cathode of diode V1, one end of resistor R2, the source of MOSFET T1, and the cathode of diode V3. The other end of resistor R1 is connected to the anode of diode V2 and one end of resistor R3. The cathode of diode V2 is connected to the anode of battery charging interface J2 and the drain of MOSFET T1. The other end of resistor R3 is connected to the cathode of diode V4 and the negative input terminal of comparator U1. The anode of diode V4 is grounded. The connection point between the cathode of diode V2 and resistor R3 is designated as sampling point C. The positive input terminal of the comparator is connected to one end of resistor R7, one end of resistor R6, and one end of resistor R8. The other end of resistor R8 is grounded. The other end of resistor R7 is connected to the reference voltage Vref. The output terminal of comparator U1 is connected to the other end of resistor R6 and the input terminal of steady-state transformer U2.

[0014] Resistors R1 and R3 are current-limiting resistors. If the operating voltage of the input power supply is higher than the operating voltage of comparator U1, the voltage from the input power supply will pass through the current-limiting resistors R1 and R3 and be sent to the negative input terminal of comparator U1, which will damage the comparator. In this application, a diode V4 is set at the negative input terminal of comparator U1. Diode V4 is a port Zener diode, which regulates the voltage input to the negative input terminal of comparator U1 within a preset design range value, ensuring the safe use of comparator U1. The specific range value of V4 is set according to actual needs; in this embodiment, it is set to 3.3V.

[0015] The reference voltage Vref is divided by resistors R7 and R8 and compared with the voltage at the "-" terminal of comparator U1 to output the comparison result. The comparison result is a digital signal "0" or "1". The digital signal is adjusted by the external voltage of comparator U1, and the output is either high or low. The specific voltage amplitude of the high level is determined by the amplitude of the external voltage. In this embodiment, the high level output of comparator U1 is 5V, and the low level is 0V.

[0016] Resistor R1 is a current-limiting resistor to prevent excessive current from burning out the circuit. The voltage difference between the sampling point C of the anode of diode V2 and the cathode of diode V2 is used to determine the battery connection status: normal connection, no battery connected, battery automatically shut off, or battery reversed. When the battery is normally connected and in the battery automatically shut-off state, the voltage at the cathode of diode V2 is used to wake up the battery. The voltage at the anode of diode V2 is the voltage drop caused by the current through resistor R1, and the diode conducts to wake up the battery for charging. When the battery is reversed, the output voltage flows through the positive terminal of Zener diode V4 to the negative terminal of V4, and through resistor R3 (current-limiting resistor) to the positive terminal C of diode V2. The voltage at the negative terminal of diode V2 flows to the battery, and the voltage at the sampling point C of the anode of diode V2 is pulled down to a negative voltage. When the battery is off or not connected, the voltage at the cathode of diode V2 is 0V, and the voltage at sampling point C is the voltage drop caused by the current through resistor R1, and the diode conducts.

[0017] In order to enable the switch control circuit to be turned on or off based on the judgment result of the battery connection judgment circuit, a steady-state circuit is also provided in this application.

[0018] The steady-state circuit includes: resistor R5 and steady-state transformer U2; the end of resistor R5 is connected to the output of steady-state transformer U2, and the input of steady-state transformer U2 is connected to the output of comparator U1.

[0019] The switching control circuit controls the voltage change at the gate (G) of the field-effect transistor T1, thereby controlling the switching of the field-effect transistor T1.

[0020] This application designs a stabilizer circuit to ensure the safe use of the field-effect transistor T1 and extend the circuit's lifespan. The comparator U1 in this application outputs a comparison result of 1 or 0, with a reference voltage Vref of 2.5V and a Vcc voltage of 5V. The output of comparator U1 is adjusted by an external voltage regulator to 5V and 0V before being fed into subsequent circuit components. However, because the output of comparator U1 is determined based on the comparison result between the reference voltage at its positive input and the negative input, when the voltage at the negative input of comparator U1 is lower than the design range of the Zener diode V4, the negative input voltage is directly compared with the reference voltage Vref at the positive input. If the negative input voltage is unstable, fluctuating between high and low, and the output level of comparator U1 fluctuates between high and low, a processing time is required. Moreover, when the time interval between two comparison operations is short, the output level of comparator U1 will change frequently, and the level sent to subsequent circuits may even be between 0V and 5V. If the output voltage of comparator U1 is directly connected to the drain of MOSFET T1, the drain of MOSFET T1 will not be fully turned on or off, resulting in MOSFET T1 being in a half-open, half-closed state. When the internal resistance of MOSFET T1 increases during switching on and off, it will cause T1 to not be fully turned on or off, and MOSFET T1 will be damaged quickly. In this application, a suitable model of stabilizer U2 is selected, and a threshold is set for the output voltage signal of the comparator according to the parameters of stabilizer U2 to determine high voltage and low voltage. For example, a voltage higher than 3.6V is considered high voltage, and a voltage lower than 0.5V is considered low voltage. This reduces the probability of frequent changes in the drain voltage of MOSFET T1 and also reduces the probability of MOSFET T1 being damaged.

[0021] The input voltage J1 outputs through the negative terminal of diode V1 to the negative terminal of Zener diode V3. The negative terminal of Zener diode V3 is connected to the input terminal S of MOSFET T1, and the positive terminal of V3 is connected to the control terminal G of MOSFET T1. Zener diode V3 protects the MOSFET control voltage within its specified operating range. The input S and control G of MOSFET T1 are divided by resistors R2 and R4. The common point of the voltage divider from resistors R2 and R4 is connected to the control terminal G of MOSFET T1. The input S of MOSFET T1 passes through resistor R1 to point C. Point C is connected to the positive terminal of the battery via the negative terminal of diode V2 to wake up the battery charging process. Resistor R1 to point C is also connected to the negative terminal of comparator chip U1 via resistor R3. Point C is connected to the battery charging port via diode V2 to determine if the battery power supply and installation are correct. The negative terminal of chip U1 is connected to ground via Zener diode V4. Zener diode V4 prevents overvoltage and avoids burning out the negative terminal of comparator chip U1. The reference voltage Vref is divided by resistors R7 and R8 and compared with the negative voltage of comparator U1. The comparator U1 outputs the comparison result as the control voltage. The control voltage is stabilized by stabilizer U2 to output either "1" or "0", and then sent to control transistor Q1 to control the switching voltage output of power MOSFET T1. MOSFET T1 is used to adjust the normal charging of the battery and to check for reverse wiring. This circuit has a simple structure, automatically detects wiring errors, avoids equipment burnout, and effectively improves charging safety.

[0022] Specifically, the switch control circuit opens or closes the switching device in the switch control circuit based on the judgment result of the battery connection judgment circuit, thereby controlling whether to charge the battery according to the judgment result of the battery connection judgment circuit; the specific steps include: a1: The battery connection judgment circuit sets up a sampling point C. The voltage at sampling point C is used to determine the current battery output voltage through diode V2. The battery output voltage indicates the current battery connection direction.

[0023] a2: The voltage at sampling point C is fed into comparator U1 through resistor R3. Comparator U1 compares the voltage at sampling point C with the reference voltage Vref and outputs the comparison result. The comparison result is converted into an output level and then sent to the steady-state circuit. The comparison results include: 1 and 0; Where 0 indicates that the voltage at sampling point C received by input comparator U1 is higher than the reference voltage; 1 indicates that the voltage at sampling point C received by input comparator U1 is not higher than the reference voltage. When the comparison result is 0, the judgment result of the battery connection judgment circuit is: the battery connection is correct; When the comparison result is 1, the judgment result of the battery connection judgment circuit is: the battery connection is reversed.

[0024] This application also includes a steady-state circuit. The comparator U1 converts the comparison result into an output level and sends it to the steady-state circuit. The steady-state circuit stabilizes the voltage of the comparison result and sends the stable control voltage signal to the switch control circuit.

[0025] When the battery wiring is not reversed, the continuously input comparison results are sent to the steady-state device U2, and the stable voltage output is the control voltage signal 1 based on high voltage; when the battery wiring is reversed, the continuously input comparison results are sent to the steady-state device U2, and the stable voltage output is the control voltage signal 0 based on low voltage.

[0026] a3: The switch control circuit controls the opening or closing of the switching device in the switch control circuit based on the input voltage signal; The switching device in the switching control circuit is a field-effect transistor T1; After receiving control voltage signal 1, the switch control circuit opens the switch of MOSFET T1, and the input power supplies charge the battery; after receiving control voltage signal 0, the switch control circuit closes the switch of MOSFET T1, and the input power supplies stop charging the battery.

[0027] The judgment process described above in this application is automatically implemented based on the physical connection of the circuit. It does not require software adjustment or calculation by a central chip. The whole process is fast. Once the circuit environment changes, the corresponding judgment can be quickly realized. The overall circuit structure is simple, the security is high, and it can adapt to more scenarios.

[0028] If the battery is connected in reverse in battery interface J2, the positive terminal of the battery is grounded, resulting in a negative output voltage. The connection point between the negative terminal of diode V2 and the battery in the battery connection judgment circuit is also negative. Since the resistance of resistor R1 is relatively large (set to 20kΩ in this embodiment), the current flowing through resistor R1 is small. Therefore, the voltage at sampling point C, where the positive terminal of diode V2 is located, is negative. With the anode of the Zener diode V4 grounded, the current flows through Zener diode V4, resistor R3, point C, and the negative terminal of V2. That is, the voltage input to the negative terminal of comparator U1 via point C and resistor R3 is also negative. The negative input of comparator U1 is lower than the positive input. If the reference voltage Vref connected to the input terminal is used, the comparison result of comparator U1 is 1. After the comparison result is shaped by stabilizer U2, a switch control voltage signal 0 based on low voltage is obtained. The base input of transistor Q1 in the switch control circuit is the low voltage signal 0. The emitter of transistor Q1 is grounded. The base voltage of transistor Q1 is not higher than the emitter voltage, so transistor Q1 is turned off. The voltage difference between the gate G and the source S of field-effect transistor T1 is basically equal, so the source and drain of field-effect transistor T1 are disconnected, that is, the switch control circuit for battery charging is turned off.

[0029] When the battery is not connected, or when the battery wiring is normal but the battery shuts off automatically for some reason, the switch control circuit for battery charging determines the switch state by the voltage and wiring judgment circuit. The voltage difference between the positive terminal of diode V2 and the battery is 0.7V. The current flowing through resistor R1 passes through collector C, where the voltage is positive. This voltage flows through diode V2 to the battery to wake up the battery and start charging. At the same time, the voltage at collector C flows through resistor R3 to the negative input of comparator U1. The voltage input to the negative terminal of comparator U1 is relatively large. Zener diode V4 stabilizes the voltage input to the negative terminal of U1 within a preset range, which is 3.3V in this embodiment. Therefore, the 3.3V input to the negative terminal of comparator U1 is greater than the voltage divider input to the positive terminal, and the comparator U1 outputs a comparison result of 0. After passing through stabilizer U2, a stable control voltage signal 1 is obtained. Transistor Q1 connected to stabilizer U2 turns on, and the voltage difference between the gate G and source S of field-effect transistor T1 increases. Thus, the source and drain of field-effect transistor T1 are in the open state, that is, the switch control circuit for battery charging is in the open state.

[0030] In certain special circumstances, such as when the battery is first connected to the battery interface J2, or when the battery is depleted and automatically shuts down due to special circumstances, once the input power returns to normal, the input power can directly trigger the battery with a higher voltage through the resistor R1 and diode V2 branch in the circuit, causing the battery to start and enter the charging state. The whole process is completed automatically without manual intervention.

[0031] When the battery is properly connected and energized, the voltage at the cathode of diode V2 is the battery's output voltage, and the voltage at the anode of diode V2 is the voltage drop caused by the current flowing through resistor R1. Simultaneously, the current flowing through resistor R1 passes through R3 and is fed into the "-" terminal of comparator U1. The Zener diode V4 stabilizes the voltage input to the "-" terminal of U1 at a preset value of 3.3V, and the comparator U1 outputs a comparison result of 0. After stabilization by the stabilizer U2, a stable control voltage signal 1 is obtained, which is connected to transistor Q1 and MOSFET T1, meaning the battery charging switch control circuit is in the open state.

Claims

1. A power supply protection circuit, comprising: The circuit includes an input power supply and a storage battery, wherein the input power supply is connected to the circuit via a power interface J1 and the storage battery is connected to the circuit via a storage battery interface J2. The circuit is characterized by further including a storage battery connection judgment circuit and a switch control circuit. The input power supply charges the battery through the switch control circuit; The battery connection judgment circuit is used to determine whether the battery is reversed. If the battery is not reversed, the switch control circuit is normally open, and the input power supply charges the battery through the switch control circuit. If the battery is reversed, the switch control circuit is turned off through the battery connection judgment circuit, and the input power supply stops charging the battery. The switching control circuit includes: a Zener diode V3, a transistor Q1, a resistor R2, a resistor R4, a resistor R5, and a field-effect transistor T1; the field-effect transistor T1 is a PMOS transistor. The negative terminal of the Zener diode V3, one end of the resistor R2, and the source of the field-effect transistor T1 are connected to the input power supply. The positive terminal of the Zener diode V3 is connected to the other end of the resistor R2, the gate of the field-effect transistor T1, and one end of the resistor R4. The other end of the resistor R4 is connected to the collector of the transistor Q1. The emitter of the transistor Q1 is grounded, and the base of the transistor Q1 is connected to one end of the resistor R5.

2. The power supply protection circuit according to claim 1, characterized in that: The input power supply is connected to the battery connection judgment circuit and the switch control circuit via diode V1.

3. The power supply protection circuit according to claim 1, characterized in that: The battery connection determination circuit includes: resistor R1, resistor R3, diode V2, diode V4, comparator U1, resistor R6, resistor R7, and resistor R8. One end of the resistor R1 is connected to the input power supply, the other end of the resistor R1 is connected to one end of the resistor R3 and the positive terminal of the diode V2, the negative terminal of the diode V2 is connected to the drain of the field-effect transistor T1 and the battery interface J2, the other end of the resistor R3 is connected to the negative terminal of the diode V4, and the positive terminal of the diode V4 is grounded. The negative input terminal of the comparator U1 is connected to the negative terminal of the diode V4, and the positive input terminal of the comparator U1 is connected to one end of the resistor R7, one end of the resistor R6, and one end of the resistor R8. The other end of the resistor R8 is grounded, and the other end of the resistor R7 is connected to the reference voltage Vref. The output terminal of the comparator U1 is connected to the other end of the resistor R6.

4. The power supply protection circuit according to claim 3, characterized in that: It also includes: steady-state circuits; The steady-state circuit includes: a steady-state device U2; the output terminal of the steady-state device U2 is connected to the other end of the resistor R5, and the input terminal of the steady-state device U2 is connected to the output terminal of the comparator U1.

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