A battery charging and discharging and protection power supply switching circuit

Abstract

The present invention discloses a battery charging and discharging and protection power supply switching circuit, including a charging control module for charging a rechargeable battery, a battery discharge module for controlling the discharge of the rechargeable battery, and an over-discharge prevention module connected to the battery discharge module for controlling the over-discharge of the rechargeable battery; therefore, the present invention has the following advantages: convenient and fast, no need to disassemble the battery in a charging manner, automatic power off when the battery power is insufficient, no damage to the battery due to long-term over-discharge, and no loss of manpower and material resources caused by frequent battery replacement. It effectively increases the service life of the battery and reduces the workload of equipment maintenance and replacement due to battery problems, thereby improving the efficiency of equipment use.

Description

Technical Field

[0001] The present invention relates to a battery charging and discharging, protection circuit and power supply switching. It includes shutting down the battery output when the battery is undervoltage to prevent the battery from being over-discharged, charging the battery, stopping charging when the battery is full, automatically switching to the external power supply when the external power supply is supplied, and shutting down the battery power supply. It specifically relates to a battery charging and discharging and protection power supply switching circuit Background Art

[0002] The charging circuit modules currently on the market only charge rechargeable batteries, without overcharge protection and over-discharge protection, which has a certain impact on the service life of rechargeable batteries and the stable operation of equipment.

[0003] When the device is connected to an external power source, there is no corresponding power supply switching function, so the rechargeable battery is always in a discharge state and cannot be well utilized. When there is an external power supply resource, turn off the rechargeable battery power supply to more efficiently and accurately shut down the output of the rechargeable battery when it is not necessary, and put it to use immediately when it is necessary, so as to better store energy and save energy. Reduce unnecessary charging times, effectively increase the battery life, and make it more durable. Summary of the invention

[0004] The above technical problems of the present invention are mainly solved by the following technical solutions:

[0005] A battery charging and discharging and protection power supply switching circuit, characterized in that it comprises a charging control module for charging a rechargeable battery, a battery discharging module for controlling the discharge of the rechargeable battery, and an over-discharging prevention module connected to the battery discharging module for controlling the over-discharging of the rechargeable battery;

[0006] The battery discharge module includes a chip U3 of model LTC4412 and a chip U4 of model LTC4412; the nominal voltage VBAT-7.4V is output from pin 1 of the lithium battery J2, which enters pin 1 of U3 after filtering through the ground capacitor C9, pin 2 of U3 is grounded, pin 3 of U3 is connected to the CTL_ON / OFF signal, pin 4 of U3 is suspended, pin 6 of U3 is grounded, pin 5 of U3 is connected to the gate of the field effect transistor Q3, a resistor R10 is connected between the gate and source of Q3, the drain of Q3 enters pin 1 of U4 after passing through the ground capacitor C8, pin 2 of U4 is grounded, pin 3 of U4 divides the 9.4V_charge voltage through resistors R17 and R18, one path of pin 5 of U4 is connected in series with LED5 through R9 for voltage switching indication, the other path of pin 5 of U4 is connected to the gate of Q4, pin 6 of U4 is connected to the source of Q4, pin 4 of U4 is connected to the gate of Q2, and pin 4 of U4 is connected to the gate of Q2. Resistor R8 is connected between pin 1 and pin 6; when the 8.7V_charge voltage of field effect tube Q2 is connected, the source and drain of Q2 are turned on, and at the same time, the 9.4V_charge of chip U4 outputs a high level through the voltage divider R17 and R18 to control the 5th pin of chip U4, and the resistor Q4 is turned on, so that the load J3 is powered by the external voltage 8.7V_charge, and the VBAT-7.4V of the lithium battery is blocked by the resistance of Q4 and cannot power the load J3; when the 8.7V_charge voltage of field effect tube Q2 is cancelled, the 9.4V_charge also disappears. At this time, Q3 and Q4 are turned on under the control of U3 and U4 respectively, so that the VBAT-7.4V of the lithium battery passes through the field effect tubes Q3 and Q4, the unidirectional diode D4, the ground filter capacitors C10 and C11, and the electric fuse F2 to power the load J3; the power supply switching between the external power supply and the built-in lithium battery is realized.

[0007] The charging control module includes a chip U1 with a model number of TPS5430DDA and a chip U2 with a model number of GS7001-SOP8L. An external 12V power supply is introduced through a J1 plug, and enters the 7th pin of the chip U1 after passing through an electric fuse F1, a TVS1 suppression tube, and capacitors C3 and C4 to ground. Pins 2 and 3 of U1 are suspended, pins 6 and 7 of U1 are grounded, pin 5 is connected to ground with a resistor R7, and pin 7 is connected to a resistor R5. Pin 8 of U1 is the output voltage, a filter capacitor C2 is connected between pins 8 and 1, a diode D2 is connected to pin 8, and a resistor R2 to ground is connected to pin 4. After R1_1, R1_2, and pin 8 pass through the inductor L1, a 9.4V_charge voltage is output. Pin 8 is connected to capacitors C5, C6, E1, resistor R6 and indicator LED3. The 9.4V_charge output voltage passes through diode D1 to form a voltage of 8.7V_charge. The 8.7V_charge voltage is connected to capacitor C1 to ground, and then connected to pin 7 of chip U2 through R3 and LED2, and to pin 1 of chip U2 through R4 and LED1. LED2 lights up when the lithium battery is not fully charged, and LED1 lights up when it is fully charged. Pin 2 of U2 is connected to resistor Rts1 to ground, and pin 3 of U2 is grounded. Pin 8 of U2 is used as the input end of the charging voltage 8.7V_charge, which charges the lithium battery J2 after passing through R1, Q1 and D3.

[0008] The over-discharge protection module includes a chip U6 with a model number of LM1117S-2.5, a chip U5 with a model number of REF3318, and a comparison chip U7A; the voltage VBAT-7.4V of the lithium battery is connected to a capacitor C13 to ground, and is connected to pin 3 of the chip U6, and then pin 1 of U6 is grounded, and pins 2 and 4 of U6 are connected as an output voltage of 2.5V, and the output point voltage is connected to capacitors C15 and C16 to ground. The 2.5V voltage output by U6 is used as the input of pin 1 of U5, pin 3 of U5 is grounded, and pin 2 of U5 outputs a 1.8V voltage, and the 1.8V voltage is connected to capacitor C14 to ground. At the same time, this voltage is used as the input of pin 3 of chip U7A, and pin 2 of U7A is connected to resistors R12, R13, and R14; pin 8 of U7A is connected to the voltage VBA of the lithium battery T-7.4V, capacitor C17 is connected to ground, resistor R11 is connected between pins 1 and 8 of U7A, pin 4 of U7A is grounded, and pin 1 of U7A is connected to resistor R16 and indicator LED6; in actual operation, when the VBAT-7.4V voltage of the lithium battery drops below 7.2V, pin 1 of U7A outputs a high level, at this time CTL_ON / OFF is a high level, pin 3 of the control chip U3 is a high level, and U3 controls the field effect transistor Q3 to be turned off through pin 5. At this time, the path from the VBAT-7.4V voltage of the lithium battery J2 to the load J3 is cut off, and the lithium battery cannot discharge to the load, thereby protecting the lithium battery from over-discharge; at the same time, when CTL_ON / OFF is a high level, LED6 lights up, indicating that the lithium battery is undervoltage.

[0009] In the above-mentioned battery charging, discharging and protection power supply switching circuit, it also includes a battery power supply indication module, which includes a chip U7B. The lithium battery voltage VBAT-7.4V is connected to the 6th pin of U7B through the R20 resistor, and the 6th pin is connected to R19 to the ground. Another 8.7V_charge is connected to the 5th pin of U7B through the resistor R22. The 5th pin of U7B is connected to the ground with the resistor R23. The 7th pin of U7B is connected to the indicator LED4 and the resistor R21 to the lithium battery voltage VBAT-7.4V. When the external voltage 8.7V_charge is connected, a high level is generated through the 7th pin of the U7B chip, and LED4 is off at this time, indicating that the external power supply is supplied; when the external voltage 8.7V_charge is disconnected, the 7th pin of the chip U7B generates a low level, and LED4 is lit at this time, indicating that the lithium battery is supplying power; thereby completing the battery power supply indication function.

[0010] Therefore, the present invention has the following advantages: convenient and fast, no need to disassemble the battery during charging, automatic power off when the battery is low, no damage to the battery due to long-term over-discharge, and no loss of manpower and material resources caused by frequent battery replacement. It effectively increases the battery life and reduces the workload of equipment maintenance and replacement due to battery problems, thereby improving the efficiency of equipment use. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the charging control module circuit structure.

[0012] Figure 2 This is a schematic diagram of the battery discharge module circuit structure.

[0013] Figure 3 Schematic diagram of the circuit structure of the over-discharge prevention module.

[0014] Figure 4 This is a schematic diagram of the battery power indication circuit structure.

[0015] Figure 5 It is a schematic diagram of the module connection structure of the present invention. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0017] Example:

[0018] First, the circuit structure of the present invention is introduced:

[0019] It includes a charging control module for charging the rechargeable battery, a battery discharge module for controlling the discharge of the rechargeable battery, and an over-discharge prevention module connected to the battery discharge module for controlling the over-discharge of the rechargeable battery;

[0020] The battery discharge module includes a chip U3 of model LTC4412 and a chip U4 of model LTC4412; the nominal voltage VBAT-7.4V is output from pin 1 of the lithium battery J2, which enters pin 1 of U3 after filtering through the ground capacitor C9, pin 2 of U3 is grounded, pin 3 of U3 is connected to the CTL_ON / OFF signal, pin 4 of U3 is suspended, pin 6 of U3 is grounded, pin 5 of U3 is connected to the gate of the field effect transistor Q3, a resistor R10 is connected between the gate and source of Q3, the drain of Q3 enters pin 1 of U4 after passing through the ground capacitor C8, pin 2 of U4 is grounded, pin 3 of U4 divides the 9.4V_charge voltage through resistors R17 and R18, one path of pin 5 of U4 is connected in series with LED5 through R9 for voltage switching indication, the other path of pin 5 of U4 is connected to the gate of Q4, pin 6 of U4 is connected to the source of Q4, pin 4 of U4 is connected to the gate of Q2, and pin 4 of U4 is connected to the gate of Q2. Resistor R8 is connected between pin 1 and pin 6; when the 8.7V_charge voltage of field effect tube Q2 is connected, the source and drain of Q2 are turned on, and at the same time, the 9.4V_charge of chip U4 outputs a high level through the voltage divider R17 and R18 to control the 5th pin of chip U4, and the resistor Q4 is turned on, so that the load J3 is powered by the external voltage 8.7V_charge, and the VBAT-7.4V of the lithium battery is blocked by the resistance of Q4 and cannot power the load J3; when the 8.7V_charge voltage of field effect tube Q2 is cancelled, the 9.4V_charge also disappears. At this time, Q3 and Q4 are turned on under the control of U3 and U4 respectively, so that the VBAT-7.4V of the lithium battery passes through the field effect tubes Q3 and Q4, the unidirectional diode D4, the ground filter capacitors C10 and C11, and the electric fuse F2 to power the load J3; the power supply switching between the external power supply and the built-in lithium battery is realized.

[0021] The charging control module includes a chip U1 with model TPS5430DDA and a chip U2 with model GS7001-SOP8L. The external 12V power supply is introduced through the J1 plug, and enters the 7th pin of the chip U1 after passing through the electric fuse F1, TVS1 suppression tube, and the ground capacitors C3 and C4. The 2nd and 3rd pins of U1 are suspended, the 6th and 7th pins of U1 are grounded, the 5th pin is connected to the ground with resistor R7, and the 7th pin is connected to resistor R5. The 8th pin of U1 is the output voltage, the filter capacitor C2 is connected between the 8th pin and the 1st pin, the 8th pin is connected to the D2 diode, the 4th pin is connected to the ground resistor R2, R1_1, R1_2, and the 8th pin passes through the L1 inductor to output the 9.4V_charge voltage, 8 The pin is also connected to the ground capacitors C5, C6, E1, resistor R6 and indicator LED3. The 9.4V_charge output voltage forms a voltage of 8.7V_charge after passing through the D1 diode. The 8.7V_charge voltage is connected to the ground capacitor C1, and then connected to the 7th pin of the chip U2 through R3 and LED2, and to the 1st pin of the chip U2 through R4 and LED1. When the lithium battery is not fully charged, LED2 is on, and when it is fully charged, LED1 is on. Pin 2 of U2 is connected to the ground resistor Rts1, and pin 3 of U2 is grounded. Pin 8 of U2 is used as the input end of the charging voltage 8.7V_charge, and the lithium battery J2 is charged after passing through R1, Q1 and D3.

[0022] The over-discharge protection module includes a chip U6 with a model number of LM1117S-2.5, a chip U5 with a model number of REF3318, and a comparison chip U7A; the voltage VBAT-7.4V of the lithium battery is connected to a capacitor C13 to ground, and is connected to pin 3 of the chip U6, and then pin 1 of U6 is grounded, and pins 2 and 4 of U6 are connected as an output voltage of 2.5V, and the output point voltage is connected to capacitors C15 and C16 to ground. The 2.5V voltage output by U6 is used as the input of pin 1 of U5, pin 3 of U5 is grounded, and pin 2 of U5 outputs a 1.8V voltage, and the 1.8V voltage is connected to capacitor C14 to ground. At the same time, this voltage is used as the input of pin 3 of chip U7A, and pin 2 of U7A is connected to resistors R12, R13, and R14; pin 8 of U7A is connected to the voltage VBA of the lithium battery T-7.4V, capacitor C17 is connected to ground, resistor R11 is connected between pins 1 and 8 of U7A, pin 4 of U7A is grounded, and pin 1 of U7A is connected to resistor R16 and indicator LED6; in actual operation, when the VBAT-7.4V voltage of the lithium battery drops below 7.2V, pin 1 of U7A outputs a high level, at this time CTL_ON / OFF is a high level, pin 3 of the control chip U3 is a high level, and U3 controls the field effect transistor Q3 to be turned off through pin 5. At this time, the path from the VBAT-7.4V voltage of the lithium battery J2 to the load J3 is cut off, and the lithium battery cannot discharge to the load, thereby protecting the lithium battery from over-discharge; at the same time, when CTL_ON / OFF is a high level, LED6 lights up, indicating that the lithium battery is undervoltage.

[0023] It also includes a battery power supply indication module, which includes a chip U7B. The lithium battery voltage VBAT-7.4V is connected to pin 6 of U7B through resistor R20, and pin 6 is connected to ground via R19. Another 8.7V_charge is connected to pin 5 of U7B through resistor R22, and pin 5 of U7B is connected to ground via resistor R23. Pin 7 of U7B is connected to indicator LED4 and resistor R21 to the lithium battery voltage VBAT-7.4V. When the external voltage 8.7V_charge is connected, a high level is generated through pin 7 of the U7B chip, and LED4 is off at this time, indicating that the external power supply is supplying power; when the external voltage 8.7V_charge is disconnected, pin 7 of the chip U7B generates a low level, and LED4 is on at this time, indicating that the lithium battery is supplying power; thereby completing the battery power supply indication function.

[0024] When working, as shown in the figure,

[0025] (1) J1 is the switch power supply access port. First, the external switch power supply voltage (in this example, the external switch power supply is 12V) is reduced to a voltage slightly higher than the rated voltage of the battery to be charged through the LDO step-down chip, and the battery is charged through U2. When the battery voltage reaches the rated voltage, U2 stops charging the battery by controlling Q1 to disconnect to prevent overcharging;

[0026] (2) J2 is connected to a rechargeable battery, such as a 7.4V battery pack in this example; J3 is connected to a load.

[0027] 2.1. When no external switching power supply is connected and only a rechargeable battery / battery pack is connected, the battery supplies power to the J3 load through Q3 and Q4;

[0028] 2.2. When the battery is running low due to power consumption after being powered for a period of time, U3 is controlled through pin 1 of U7 to turn off the battery output function to prevent the battery from being damaged due to over-discharge.

[0029] (3) When the external switching power supply J1 and the battery J2 are connected at the same time, the external power supply is used first. At this time, U4 controls Q4 to turn off, thereby disconnecting the battery power supply and only using the switching power supply to ensure that the battery power supply is used when it is not necessary.

[0030] (4) The lower part is the battery power indicator. When the load is powered by a battery, LED4 is on. When the load is powered by an external switching power supply, the indicator is off. It is used to assist in judging and distinguishing the power supply mode.

[0031] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A battery charging and discharging and protection power supply switching circuit, characterized in that: It includes a charging control module for charging the rechargeable battery, a battery discharge module for controlling the discharge of the rechargeable battery, and an over-discharge prevention module connected to the battery discharge module for controlling the over-discharge of the rechargeable battery; The battery discharge module includes a chip U3 of model LTC4412 and a chip U4 of model LTC4412; the nominal voltage VBAT-7.4V is output from pin 1 of the lithium battery J2, which enters pin 1 of U3 after filtering through the ground capacitor C9, pin 2 of U3 is grounded, pin 3 of U3 is connected to the CTL_ON / OFF signal, pin 4 of U3 is suspended, pin 6 of U3 is grounded, pin 5 of U3 is connected to the gate of the field effect transistor Q3, a resistor R10 is connected between the gate and source of Q3, the drain of Q3 enters pin 1 of U4 after passing through the ground capacitor C8, pin 2 of U4 is grounded, pin 3 of U4 divides the 9.4V_charge voltage through resistors R17 and R18, one path of pin 5 of U4 is connected in series with LED5 through R9 for voltage switching indication, the other path of pin 5 of U4 is connected to the gate of Q4, pin 6 of U4 is connected to the source of Q4, pin 4 of U4 is connected to the gate of Q2, and pin 4 of U4 is connected to the gate of Q2. Resistor R8 is connected between pin 1 and pin 6; when the 8.7V_charge voltage of field effect tube Q2 is connected, the source and drain of Q2 are turned on, and at the same time, the 9.4V_charge of chip U4 outputs a high level through the voltage divider R17 and R18 to control the 5th pin of chip U4, and the resistor Q4 is turned on, so that the load J3 is powered by the external voltage 8.7V_charge, and the VBAT-7.4V of the lithium battery is blocked by the resistance of Q4 and cannot power the load J3; when the 8.7V_charge voltage of field effect tube Q2 is cancelled, the 9.4V_charge also disappears. At this time, Q3 and Q4 are turned on under the control of U3 and U4 respectively, so that the VBAT-7.4V of the lithium battery passes through the field effect tubes Q3 and Q4, the unidirectional diode D4, the ground filter capacitors C10 and C11, and the electric fuse F2 to power the load J3; the power supply switching between the external power supply and the built-in lithium battery is realized; The charging control module includes a chip U1 with a model number of TPS5430DDA and a chip U2 with a model number of GS7001-SOP8L. An external 12V power supply is introduced through a J1 plug, and enters the 7th pin of the chip U1 after passing through an electric fuse F1, a TVS1 suppression tube, and capacitors C3 and C4 to ground. Pins 2 and 3 of U1 are suspended, pins 6 and 7 of U1 are grounded, pin 5 is connected to ground with a resistor R7, and pin 7 is connected to a resistor R5. Pin 8 of U1 is the output voltage, a filter capacitor C2 is connected between pins 8 and 1, a diode D2 is connected to pin 8, and a resistor R2 to ground is connected to pin 4. After R1_1, R1_2, and pin 8 pass through the inductor L1, a 9.4V_charge voltage is output. Pin 8 is connected to capacitors C5, C6, E1, resistor R6 and indicator LED3. The 9.4V_charge output voltage forms a voltage of 8.7V_charge after passing through diode D1. The 8.7V_charge voltage is connected to capacitor C1 to ground, and then connected to pin 7 of chip U2 through R3 and LED2, and connected to pin 1 of chip U2 through R4 and LED1. When the lithium battery is not fully charged, LED2 is on, and when it is fully charged, LED1 is on. Pin 2 of U2 is connected to resistor Rts1 to ground, and pin 3 of U2 is grounded. Pin 8 of U2 is used as the input end of the charging voltage 8.7V_charge, and charges the lithium battery J2 after passing through R1, Q1 and D3. The over-discharge protection module includes a chip U6 with a model number of LM1117S-2.5, a chip U5 with a model number of REF3318, and a comparison chip U7A; the voltage VBAT-7.4V of the lithium battery is connected to a capacitor C13 to ground, and is connected to pin 3 of the chip U6, and then pin 1 of U6 is grounded, and pins 2 and 4 of U6 are connected as an output voltage of 2.5V, and the output point voltage is connected to capacitors C15 and C16 to ground. The 2.5V voltage output by U6 is used as the input of pin 1 of U5, pin 3 of U5 is grounded, and pin 2 of U5 outputs a 1.8V voltage, and the 1.8V voltage is connected to capacitor C14 to ground. At the same time, this voltage is used as the input of pin 3 of chip U7A, and pin 2 of U7A is connected to resistors R12, R13, and R14; pin 8 of U7A is connected to the voltage VBA of the lithium battery T-7.4V, capacitor C17 is connected to ground, resistor R11 is connected between pins 1 and 8 of U7A, pin 4 of U7A is grounded, and pin 1 of U7A is connected to resistor R16 and indicator LED6; in actual operation, when the VBAT-7.4V voltage of the lithium battery drops below 7.2V, pin 1 of U7A outputs a high level, at this time CTL_ON / OFF is a high level, pin 3 of the control chip U3 is a high level, and U3 controls the field effect transistor Q3 to be turned off through pin 5. At this time, the path from the VBAT-7.4V voltage of the lithium battery J2 to the load J3 is cut off, and the lithium battery cannot discharge to the load, thereby protecting the lithium battery from over-discharge; at the same time, when CTL_ON / OFF is a high level, LED6 lights up, indicating that the lithium battery is undervoltage.

2. A battery charging and discharging and protection power supply switching circuit according to claim 1, characterized in that: It also includes a battery power supply indication module, which includes a chip U7B. The lithium battery voltage VBAT-7.4V is connected to pin 6 of U7B through resistor R20, and pin 6 is connected to ground via R19. Another 8.7V_charge is connected to pin 5 of U7B through resistor R22, and pin 5 of U7B is connected to ground via resistor R23. Pin 7 of U7B is connected to indicator LED4 and resistor R21 to the lithium battery voltage VBAT-7.4V. When the external voltage 8.7V_charge is connected, a high level is generated through pin 7 of the U7B chip, and LED4 is off at this time, indicating that the external power supply is supplying power; when the external voltage 8.7V_charge is disconnected, pin 7 of the chip U7B generates a low level, and LED4 is on at this time, indicating that the lithium battery is supplying power; thereby completing the battery power supply indication function.

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