Battery under-voltage lockout circuit with time delay and voltage hysteresis functions

Abstract

The utility model provides a battery under-voltage lockout circuit with time delay and voltage hysteresis functions, and aims to solve the problems of ringing phenomenon of a power switch and mistaken power failure of a battery under-voltage protection circuit in the prior art. According to the circuit, a voltage hysteresis function is realized through positive feedback of the operational amplifier, and the problem of frequent switching of a power supply caused by voltage springback after a battery suddenly disconnects a load is avoided. Meanwhile, by adopting a comparator combination designed by an RC integrating circuit and an operational amplifier, when the power supply is interfered or the load current suddenly changes, the power supply can be effectively prevented from being cut off by mistake, and normal operation of equipment is ensured. Through flexible design of hysteresis voltage and delay parameters, the circuit can be adjusted according to different battery characteristics, has relatively high adaptability and reliability, remarkably improves the protection effect of the battery and an equipment circuit, and enhances the stability and practicability of a system.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic circuit field especially relates to a battery under -voltage lockout circuit with delay and voltage hysteresis function. BACKGROUND

[0002] In the battery-powered device, in order to prevent the performance decline caused by battery overdischarge even permanent damage, usually need to design battery under -voltage protection function. Common realization mode is to adopt battery under -voltage lockout circuit, through monitoring battery voltage, when battery voltage is below the set lockout threshold voltage, close power supply path, cut off the connection of device and battery, thereby protecting the battery from overdischarge. When battery voltage recovers higher than the lockout threshold voltage, circuit reopens power supply path, recovers the normal power supply of device.

[0003] However, the above-mentioned traditional scheme has following two significant problems in practical application:

[0004] First, when battery voltage drops below the lockout threshold voltage, the circuit closes the power supply path. But due to the voltage rebound characteristic of the battery, after stopping the output current, the battery voltage can rebound rapidly to a level higher than the lockout threshold voltage, causing the circuit to reopen the power supply path. This repeated switching operation can cause the ringing phenomenon of power supply on-off, not only interferes with the stable operation of the device, but also can damage the device or power supply.

[0005] Secondly, in the case of external negative pulse interference or load current instantaneous increase, the battery voltage can drop below the lockout threshold voltage for a short time, triggering the misoperation of the lockout circuit to cut off the power supply. However, this voltage drop is usually a transient phenomenon and does not reflect the true under -voltage state of the battery, but the misoperation of the lockout circuit will cause the device to appear abnormal power failure, seriously affecting the reliability of the device operation.

[0006] Therefore, in view of the above-mentioned defects, it is urgent to improve the battery under -voltage protection circuit to solve the problems of voltage rebound and mislock, thereby improving the stability and reliability of the system. SUMMARY

[0007] In view of the ringing problem caused by voltage rebound and the mislock problem caused by power supply interference in the existing battery under -voltage lockout circuit, the utility model provides a battery under -voltage lockout circuit with double protection function of delay and voltage hysteresis. Through the innovative design of the circuit, the stability and reliability of the battery-powered device are improved.

[0008] To achieve the above object, the utility model adopts the technical scheme, which is a battery under-voltage lockout circuit with delay and voltage hysteresis function, the circuit includes: battery B1, voltage monitoring and feedback module, integral delay and voltage hysteresis module, relay control module and voltage output Vout, the battery B1 is used for providing power input, the voltage monitoring and feedback module includes voltage divider resistance R1, resistance R2, resistance R3, voltage comparator N1, feedback resistance R5 and diode VD1, is used for voltage division to battery voltage, and the output adaptation voltage is given to voltage comparator N1 and is monitored and compared, the integral delay and voltage hysteresis module includes resistance R4, capacitor C1 and voltage comparator N2, is used for providing delay through RC integral circuit, and forms voltage hysteresis effect, the relay control module includes relay SW1 and current -limiting resistance R6, is used for controlling the disconnection of power supply when battery voltage is lower than the set threshold.

[0009] The utility model has the following beneficial effects:

[0010] Firstly, the utility model can design hysteresis voltage flexibly. By adjusting the positive feedback characteristic of the hysteresis comparator, the appropriate hysteresis voltage range can be designed according to the characteristics of different batteries, thereby effectively avoiding the power switch ringing phenomenon caused by the voltage rebound of the battery disconnected load instant. This function not only protects the battery, but also guarantees the stable operation of the equipment circuit.

[0011] Secondly, the utility model has excellent anti-interference ability. Through the combination design of RC integral circuit and operational amplifier, the transient interference signal received by the power supply can be delayed and filtered, thereby avoiding the false triggering power-off problem caused by external interference or load current mutation, and ensuring the normal operation of the equipment in complex environment.

[0012] Thirdly, the utility model significantly improves the reliability and stability of the system. The circuit can effectively cope with complex use scenarios such as electromagnetic interference and load dynamic change, further reducing the fault risk caused by sudden conditions in system operation.

[0013] In summary, the utility model shows good practicability in protecting the battery and the equipment circuit. Not only the service life of the battery is prolonged, but also the safety and reliability of the equipment operation are significantly enhanced, which is suitable for various battery-powered equipment scenarios. DRAWINGS

[0014] Figure 1 It is the circuit schematic diagram of the utility model;

[0015] Figure 2 It is the voltage hysteresis function schematic diagram of the utility model;

[0016] Figure 3The utility model discloses voltage delay comparator parameter selection schematic diagram. DETAILED DESCRIPTION

[0017] The utility model will be further described below with reference to the drawings:

[0018] As Figure 1 Illustrate a kind of battery undervoltage lockout circuit with delay and voltage hysteresis function, the circuit includes: battery B1, voltage monitoring and feedback module, integral delay and voltage hysteresis module, relay control module and voltage output Vout;The battery B1 is used to provide power input;The voltage monitoring and feedback module includes voltage divider resistance R1, resistance R2, resistance R3, voltage comparator N1, feedback resistance R5 and diode VD1, for battery voltage is divided, output adaptation voltage to voltage comparator N1 is monitored and compared;Integral delay and voltage hysteresis module includes resistance R4, capacitor C1 and voltage comparator N2, for providing delay by RC integral circuit, and forming voltage hysteresis effect;The relay control module includes relay SW1 and current-limiting resistance R6, for controlling the disconnection of power supply when battery voltage is lower than set threshold.

[0019] Specific circuit connection is: power input terminal Vin is connected with the anode of battery B1, one end of resistance R1 and the common terminal of relay SW1 respectively, the cathode of battery B1 is grounded, the other end of resistance R1 is connected with one end of resistance R2 and the positive input terminal V+ of voltage comparator N1 respectively, the negative input terminal of comparator N1 is connected with reference voltage VT1, the other end of resistance R2 is connected with resistance R3 and one end of resistance R5 respectively, the other end of resistance R3 is grounded, the other end of resistance R5 is connected with the cathode of diode VD1, the output terminal of voltage comparator N1 is connected with one end of resistance R4, the other end of resistance R4 is connected with one end of capacitor C1 and the negative input terminal V- of second voltage comparator N2 respectively, the other end of capacitor C1 is grounded, the positive input terminal of second voltage comparator N2 is connected with reference voltage Vt2, the output terminal of second voltage comparator N2 is connected with one end of resistance R6, the other end of resistance R6 is connected with the normally closed contact of relay, the normally open contact of relay is connected with circuit output terminal Vout and the anode of diode VD1.

[0020] The principle of the utility model circuit is: when the power voltage is lower than the power under-voltage threshold, voltage comparator N1 occurs flip, after accumulating enough long time flip voltage on the integration circuit, voltage comparator N2 occurs flip, control relay SW1 power off, realize the purpose of protecting the battery when the battery voltage is too low. When relay SW1 power off, Vout has no output, R5 and VD1 have no feedback current pass, after relay SW1 power off, the role of R5 and VD1 in the feedback path makes the V+ input terminal voltage of comparator N1 reduce and form hysteresis effect. The specific performance is that if the input voltage Vin rises again to be higher than 9.53V, SW1 can be triggered to reclose, avoiding the equipment ringing phenomenon caused by the battery voltage rebound.

[0021] The input voltage Vin is 10V, for example, the hysteresis voltage is about 0.5V and the delay is about 50ms, the component parameters are set as follows: the voltage dividing resistors R1 and R2 are 100kΩ resistors, R3 is a 10kΩ resistor, R5 is a 200kΩ resistor, R4 is a 100kΩ resistor, C1 is a 4.7μF capacitor, R6 is a 10kΩ resistor, the supply voltage of Vin and N1, N2 is 10V, the reference voltage Vt1 of comparator N1 is set to 5.20V, and the reference voltage Vt2 of comparator N2 is set to 9.0V.

[0022] When Vin is 10V, the V+ input terminal voltage of voltage comparator N1 is 5.24V, which is higher than the reference voltage 5.20V, N1 comparator occurs flip, the integration delay circuit t (time constant) composed of R4 and C1 is 470ms, from Figure 3 In the integration delay circuit parameter schematic diagram, the t parameter when the voltage changes 10% is selected as the design data, and from the diagram, it can be seen that when the voltage percentage is 10%, the t value is about 0.1, that is, the integration circuit delay is about 470ms*0.1, which is 47ms. When the relay SW1 is opened, Vout outputs the power supply, VD1 is turned on, and under the action of the feedback resistor R5, the V+ input terminal voltage of voltage comparator N1 is increased to 5.45V, at this time, only when the Vin voltage is lower than 9.53V, the relay SW1 can be closed, that is, at this time Figure 2 t1 is 9.53V and t2 is 10.0V, so the hysteresis closing effect is achieved. In the designed circuit in the example, the hysteresis voltage is 0.47V, the delay time is 47ms, which meets the design requirements of the hysteresis voltage of about 0.5V and the delay of about 50ms.

Claims

1. A battery undervoltage lockout circuit with delay and voltage hysteresis functions, characterized in that, The circuit includes: a battery B1, a voltage monitoring and feedback module, an integral delay and voltage hysteresis module, a relay control module, and a voltage output Vout. The battery B1 provides power input. The voltage monitoring and feedback module includes a voltage divider resistor R1, a resistor R2, a resistor R3, a voltage comparator N1, a feedback resistor R5, and a diode VD1, used to divide the battery voltage and output an adapted voltage to the voltage comparator N1 for monitoring and comparison. The integral delay and voltage hysteresis module includes a resistor R4, a capacitor C1, and a voltage comparator N2, used to provide a delay through an RC integral circuit and create a voltage hysteresis effect. The relay control module includes a relay SW1 and a current-limiting resistor R6, used to control the power supply to disconnect when the battery voltage is lower than a set threshold.

2. The battery undervoltage lockout circuit with delay and voltage hysteresis functions according to claim 1, characterized in that, The specific circuit connections are as follows: the power input terminal Vin is connected to the positive terminal of battery B1, one end of resistor R1, and the common terminal of relay SW1. The negative terminal of battery B1 is grounded. The other end of resistor R1 is connected to one end of resistor R2 and the positive input terminal V+ of voltage comparator N1. The negative input terminal of comparator N1 is connected to the reference voltage VT1. The other end of resistor R2 is connected to one end of resistor R3 and one end of resistor R5. The other end of resistor R3 is grounded. The other end of resistor R5 is connected to the negative terminal of diode VD1. The output terminal of voltage comparator N1 is connected to one end of resistor R4. The other end of resistor R4 is connected to one end of capacitor C1 and the negative input terminal V- of second voltage comparator N2. The other end of capacitor C1 is grounded. The positive input terminal of second voltage comparator N2 is connected to the reference voltage Vt2. The output terminal of second voltage comparator N2 is connected to one end of resistor R6. The other end of resistor R6 is connected to the normally closed contact of relay. The normally open contact of relay is connected to the circuit output terminal Vout and the positive terminal of diode VD1.

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