CN201113408Y - Lithium battery power supply control protection circuit - Google Patents

Abstract

The lithium battery power supply control protection circuit and the control protection method are a circuit and method for controlling the power supply of the battery, preventing over-discharge, and completely shutting off the battery through software by detecting the battery voltage. The circuit is composed of a voltage comparison module (1), a software shutdown detection module (2), a hardware shutdown detection module (3), and a hardware startup detection module (4); among them, the voltage comparison module uses a voltage detection chip of the model HT7027 (U1), one end of the voltage detection chip is connected with one end of the shutdown button (S2) in the hardware shutdown detection module (3), and the switch transistor (Q1) in the hardware shutdown detection module (S1) is connected with the switch transistor (Q1) of the activation button (S1). The emitters are connected, the emitter of the switching transistor (Q1) is the battery input terminal, and the collector is the battery output terminal; the input terminal of the shutdown transistor (Q3) in the software shutdown detection module is connected to the control pin of the microcontroller, and the output terminal is connected to the voltage Check the output pin of the chip.

Description

Lithium battery power supply control protection circuit

technical field

The utility model is a built-up circuit based on a voltage detection chip. By detecting the voltage of the battery, the power supply of the battery is controlled to prevent over-discharge, and the battery can be completely shut down through software. It belongs to the technical field of electric automation device manufacturing.

Background technique

In the power load control system, a battery is installed as a backup power supply because it needs to continue to work in the event of a power failure. However, if the lithium battery is not controlled, over-discharge will cause the battery to fail, so this circuit is designed. Moreover, the existing battery discharge management chip is not only expensive, but also has a single function, which cannot satisfy function expansion.

Contents of the invention

Technical problem: The purpose of this utility model is to provide a lithium battery power supply control and protection circuit, which uses a voltage detection chip to detect the battery voltage, controls the battery discharge time, and cuts off the voltage in due course. When the working power supply of the device is cut off and the backup battery is working, after the power-off processing procedure is completed in due course, the battery power supply is directly turned off through the software. When there is no power supply, the battery power can be reused by pressing the button.

Technical solution: In order to achieve the above objectives, the lithium battery power supply control and protection circuit of the present invention is composed of a voltage comparison module, a software shutdown detection module, a hardware shutdown detection module, and a hardware startup detection module; wherein, the voltage comparison module uses the model The voltage detection chip of HT7027, one end of the voltage detection chip is connected with one end of the shutdown button in the hardware shutdown detection module, the activation button is connected with the emitter of the switching transistor in the hardware detection module, and the emitter of the switching transistor is The battery input terminal, the collector is the battery output terminal; the input terminal of the shutdown transistor in the software shutdown detection module is connected to the control pin of the single chip microcomputer, and the output terminal is connected to the output pin of the voltage detection chip.

The lithium battery power supply control and protection circuit control and protection method of the utility model controls the battery shutdown voltage by using a voltage detection chip to detect the battery voltage, and the specific method is as follows:

Pin 2 of the voltage detection chip judges whether the current voltage is higher than the cut-off voltage. If it is higher, then pin 1 of the output pin is high to provide battery power; if it is lower than the cut-off voltage, pin 1 of the output pin is low and stops Battery powered;

When the software shutdown enable terminal, that is, the base of the transistor is high, the battery power supply is provided; when it is low, the battery power supply is stopped;

When the hardware shutdown button is pressed, the battery power supply is stopped; normally, the battery power supply is provided,

When the hardware re-powers the ON button pressed, battery power is provided if the battery voltage is higher than the shutdown voltage.

Beneficial effect: the whole circuit has the following characteristics:

a) Wide range of application. It can adapt to batteries of various voltages and provide different shutdown reference voltages through resistor divider.

b) There are many extension functions. It can be turned off by software, turned off by button, and re-powered by button.

c) The circuit cost is low. Compared with dedicated battery control chips, the price can be greatly reduced due to the low requirements on chip design and manufacturing level due to the use of multiple devices to build circuits.

Description of drawings

Fig. 1 is the block diagram of circuit principle of the utility model.

Fig. 2 is the schematic circuit diagram of the utility model.

Detailed ways

The utility model adopts the mode of building a circuit, and is composed of a high-precision voltage comparison chip HT7050, a high-power triode FZT788B, and a small number of devices.

The circuit is composed of a voltage comparison module 1, a software shutdown detection module 2, a hardware shutdown detection module 3, and a hardware startup detection module 4; among them, the voltage comparison module 1 uses the voltage detection chip U1 of the model HT7027, and the voltage detection chip U1 Terminal 1 is connected to one end of the shutdown button S2 in the hardware shutdown detection module 3, the startup button S1 is connected to the emitter of the switching transistor Q1 in the hardware startup detection module 4, and the emitter of the switching transistor Q1 is the battery input terminal. The collector is the output terminal of the battery; the input terminal of the shutdown transistor Q3 in the software shutdown detection module 2 is connected to the control pin of the single-chip microcomputer, and the output terminal is connected to the output pin of the voltage detection chip U1.

Fig. 2 is the schematic circuit diagram of the utility model.

The second resistor R2, the third resistor R3, and the fifth resistor R5 are current limiting resistors.

Due to the existence of the first diode D1, in any case, the battery can only supply power to the outside, and the external voltage cannot be poured into the battery.

The model of the voltage detection chip U1 is HT7027, which is a 2.7V voltage detection chip. The first resistor R1 and the fourth resistor R4 with 1% precision are used to divide the voltage to detect the voltage of 6.3V. (Batteries with different voltages can be detected by changing the voltage dividing resistor.)

The utility model controls the battery cut-off voltage by using a voltage detection chip to detect the battery voltage, and the specific method is as follows:

Pin 2 of the voltage detection chip U1 judges whether the current voltage is higher than the cut-off voltage. If it is higher, pin 1 of the output pin is high to provide battery power; if it is lower than the cut-off voltage, pin 1 of the output pin is low. stop battery power;

When the software shutdown enable terminal, that is, the base of transistor Q3 is high, the battery power supply is provided; when it is low, the battery power supply is stopped;

When the hardware shutdown button S2 is pressed, the battery power supply is stopped; normally, the battery power supply is provided,

When the hardware is re-powered and the on button S1 is pressed, if the battery voltage is higher than the shutdown voltage, the battery power is provided.

Example:

When only powered by the battery, if the battery voltage is higher than 6.3V, the output pin 1 (OUT) of the voltage detection chip HT7027 is high, so that the first transistor Q1 and the second transistor Q2 are turned on, and the battery voltage is output to VCC22V, which is sent to the main circuit powered.

When the battery voltage is lower than 6.3V, the output pin 1 (OUT) of the voltage detection chip HT7027 is low, less than 0.7V, and the first transistor Q1 and the second transistor Q2 are cut off due to the action of the clamping second diode D2 , the battery is no longer providing power. The software shutdown control pin is connected to the pin of the single-chip microcomputer, which is usually high, the third transistor Q3 triode is cut off, and the circuit works normally.

The sixth resistor R6 and the seventh resistor R7 are voltage dividing resistors, which can make the software shutdown control pin (SHUTDOWN) adapt to the output control voltage of various single-chip microcomputers.

When the software shutdown control pin (SHUTDOWN) is set low, the third transistor Q3 transistor is turned on, causing the first transistor Q1 and the second transistor to be turned off, and the battery no longer supplies power, thus realizing software shutdown.

When the button switch S2 is pressed, the first transistor Q1 and the second transistor are turned off, and the battery no longer supplies power, realizing manual shutdown.

In the case of power failure, press the button switch S1, if the battery voltage is higher than 6.3V, the battery will re-supply.

Following is the model of each device used in the present invention:

Device number function name Device model D1 Surface mount diode MBRS240LT3 S1, S2 button B3F-400012*5 Q1 Surface Mount Transistor FZT788B Q2 Surface Mount Transistor FMMT3904 Q3 Surface Mount Transistor FMMT3906 U1 Surface mount voltage detection chip HT7027 R1 Surface Mount Resistor CR0603-1/8W-6.8K 1％ R2 Surface Mount Resistor CR0603-1/8W-20K R3 Surface Mount Resistor CR0603-1/8W-1.5K R4 Surface Mount Resistor CR0603-1/8W-5.1K 1％ R5, R7 Surface Mount Resistor CR0603-1/8W-10K R6 Surface Mount Resistor CR0603-1/8W-1k

Claims (1)

1. lithium battery power supply control protection circuit, it is characterized in that this circuit by voltage comparison module (1), software switching-off detection module (2), hardware turn-off detection module (3), hardware is opened detection module (4) and is formed; Wherein, voltage comparison module (1) is used the voltage checking chip (U1) of model as HT7027, the end that 1 end of voltage checking chip (U1) and hardware turn-off the shutoff button (S2) in the detection module (3) joins, opening button (S1) and hardware opens the emitter of the switching transistor (Q1) in the detection module (4) and joins, the emission of switching transistor (Q1) is cell input terminal very, and current collection is the battery output very; The input of the shutoff transistor (Q3) in the software switching-off detection module (2) connects the control pin of single-chip microcomputer, the output pin of output termination voltage checking chip (U1).

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