Intelligent protection circuit for lithium ion battery

Abstract

The utility model discloses an intelligent protection circuit for a lithium ion battery. The intelligent protection circuit comprises a CW1035BLAP, a T3095UMOSFET, a chip pin, a chip capacitor and a chip resistor, the chip pins comprise a VDD pin, a VC1 pin, a VC2 pin, a VM pin, a CO pin, a DO pin, an OT pin and a VSS pin; the VDD pin of the CW1035BLAP protection IC is connected with the highest potential of the battery pack, the T3095UMOSFET comprises a charging MOSFET and a discharging MOSFET, the charging MOSFET is connected between a charger and the battery pack, the grid electrode of the charging MOSFET is controlled by the CO pin of the protection IC, the discharging MOSFET is connected between the battery pack and a load, the grid electrode of the discharging MOSFET is controlled by the DO pin of the protection IC, a discharging output port can be closed during charging, and the discharging output port can be opened during discharging. A charging and discharging loop can be cut off under an abnormal condition; and the chip capacitors are respectively bridged near the VDD pin and the VSS pin.

Description

Technical Field

[0001] This utility model relates to the field of battery protection technology, and in particular to a smart protection circuit for lithium-ion batteries. Background Technology

[0002] With the widespread use of lithium-ion batteries in various electronic devices, overcharging and over-discharging are common problems that can lead to shortened battery life, performance degradation, and even safety accidents such as fires and explosions. This circuit monitors the battery voltage in real time and takes timely protective measures during overcharging and over-discharging, shutting down the corresponding MOSFETs to effectively avoid these problems, extend battery life, and ensure the safety of equipment and users.

[0003] During battery discharge, overload or short circuits can occur, leading to overcurrent, which can cause serious damage to the battery and circuit. At the same time, excessively high temperatures during charging and discharging can trigger a series of safety issues, such as thermal runaway. Therefore, a smart protection circuit for lithium-ion batteries is proposed here. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art and achieve the above-mentioned objectives, the present invention proposes the following technical solution: a lithium-ion battery intelligent protection circuit, including CW1035BLAP, T3095UMOSFET, chip pins, chip capacitors, and chip resistors.

[0005] The chip pins include VDD pin, VC1 pin, VC2 pin, VM pin, CO pin, DO pin, OT pin, and VSS pin;

[0006] The CW1035BLAP protection IC has its VDD pin connected to the highest potential of the battery pack.

[0007] The T3095UMOSFET includes a charging MOSFET and a discharging MOSFET. The charging MOSFET is connected between the charger and the battery pack, and its gate is controlled by the CO pin of the protection IC. The discharging MOSFET is connected between the battery pack and the load, and its gate is controlled by the DO pin of the protection IC. It can shut down the discharge output port during charging and cut off the charging and discharging circuit under abnormal conditions.

[0008] The surface-mount capacitors are connected across the VDD and VSS pins, respectively.

[0009] The VC1 and VC2 pins are respectively connected to the positive terminals of each individual cell in the battery pack. The VM pin is connected to the discharge MOSFET to detect the discharge current. The CO pin is connected to the gate of the charging MOSFET to control the charging circuit. The DO pin is connected to the gate of the discharge MOSFET to control the discharge circuit. The OT pin is connected to the NTC resistor for temperature detection. The VSS pin is connected to the lowest potential of the battery pack.

[0010] When the protection IC detects that the battery voltage reaches the overcharge protection voltage and the duration exceeds the overcharge protection delay time through the VC1 and VC2 pins, it outputs a high impedance state through the CO pin to turn off the charging MOSFET and stop charging. At the same time, the DO pin remains at a low level to close the discharge output port. Charging is restarted when all battery voltages are lower than the overcharge release voltage and the duration exceeds the overcharge release delay time.

[0011] When the voltage of any cell is lower than the over-discharge protection voltage and exceeds the over-discharge protection delay time, the DO pin outputs a low level to turn off the discharge MOSFET and enters the over-discharge protection state. When the voltage of the VM pin is lower than the short-circuit protection threshold and exceeds the load lockout release delay time, the lockout is released and the normal state is restored.

[0012] When the VM pin detects that the discharge MOSFET voltage is greater than the overcurrent protection threshold and remains so for longer than the overcurrent protection delay time, the DO pin outputs a low level to turn off the discharge MOSFET. The VM pin releases the overcurrent when the voltage is less than the short-circuit protection threshold and exceeds the overcurrent recovery delay time.

[0013] The OT pin detects the battery temperature through an NTC resistor. When the charging temperature reaches the preset charging over-temperature protection threshold, the protection IC triggers the charging over-temperature protection, immediately shutting off the charging MOSFET and stopping the charging process. When the VM pin is connected to a load after the charging over-temperature protection and the voltage is greater than the discharge state judgment voltage, the protection IC shields the charging over-temperature protection and turns on the charging MOSFET. When the battery pack enters the discharge over-temperature protection or the discharge MOSFET is turned off for other reasons, the charging over-temperature protection is unshielded, and the charging MOSFET is turned off again.

[0014] This utility model has the following beneficial effects:

[0015] In this invention, the battery voltage is monitored in real time via pins. When overcharged, the CO pin turns off the charging MOSFET (Q3), and when over-discharged, the DO pin turns off the discharging MOSFET (Q2). This effectively prevents overcharging and over-discharging, extends battery life, and reduces safety risks. The VM pin is used to connect to the discharging MOSFET (Q2) to detect current. When there is overcurrent, Q2 is quickly turned off, providing precise overcurrent protection and preventing battery overheating and circuit burnout. At the same time, the OT pin and NTC resistor are used to detect temperature. When the charging or discharging temperature exceeds the limit, Q3 or Q2 is turned off accordingly, providing reliable temperature protection and preventing thermal runaway. This comprehensive protection ensures battery safety and stability and ensures safe circuit operation. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a lithium-ion battery intelligent protection circuit proposed in this utility model. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model. Example

[0018] like Figure 1 As shown, the intelligent protection circuit for lithium-ion batteries proposed in this utility model has the following overall working process:

[0019] The chip pins include VDD pin (1), VC1 pin (2), VC2 pin (3), VM pin (4), CO pin (5), DO pin (6), OT pin (7) and VSS pin (8).

[0020] Normal charging process: When the charger is connected to the circuit, the charging MOSFET (Q3) is turned on under the control of the CO pin of the protection IC (assuming the battery voltage has not reached the overcharge threshold and the temperature is normal). The charger charges the battery pack through Q3. At the same time, the discharging MOSFET (Q2) is kept off under the control of the DO pin to ensure that the discharge output port is closed during charging and to prevent the charging current from flowing to the load. The protection IC monitors the battery voltage in real time through the VC1 and VC2 pins, monitors the battery temperature through the OT pin, and monitors the charging current through the VM pin (indirectly monitored through the circuit related to Q2).

[0021] Overcharge protection under abnormal conditions: When the protection IC detects that the battery voltage has reached the overcharge protection voltage (e.g., 4.225V) through the VC1 and VC2 pins for a duration exceeding the overcharge protection delay time (e.g., 1000ms), the CO pin outputs a high impedance state, turning off the charging MOSFET (Q3) and stopping charging to prevent battery damage from overcharging. Simultaneously, the DO pin remains low to ensure the discharge output port is closed. Charging will only resume when all battery voltages fall below the overcharge release voltage (e.g., 4.025V) for a duration exceeding the overcharge release delay time (e.g., 17.5ms).

[0022] Normal discharge process: When the battery needs to supply power to the load, the discharge MOSFET (Q2) is turned on under the control of the DO pin of the protection IC (assuming the battery voltage has not reached the over-discharge threshold and there are no abnormal conditions such as overcurrent or over-temperature). The battery pack supplies power to the load through Q2. At this time, the charging MOSFET (Q3) remains off to prevent the charging circuit from being turned on. The protection IC also continuously monitors parameters such as battery voltage, current, and temperature to ensure a safe and stable discharge process.

[0023] Over-discharge protection: When the voltage of any battery cell falls below the over-discharge protection voltage (e.g., 2.700V) and exceeds the over-discharge protection delay time (e.g., 1000ms), the DO terminal outputs a low level to turn off the discharge MOSFET (Q2), entering the over-discharge protection state, stopping the battery from discharging to the load, and protecting the battery. The over-discharge protection release condition is that the voltage of all batteries is higher than the over-discharge release voltage (e.g., 3.000V) and exceeds the over-discharge release delay time (e.g., 200ms). If the over-discharge load lockout state is entered when over-discharge protection is in effect and a load is connected, the DO terminal will remain low even if the battery voltage recovers. The lockout will only be released and the normal state restored after the load is removed, the voltage at the VM pin terminal is less than the short-circuit protection threshold, and the load lockout release delay time (e.g., 60ms) is exceeded.

[0024] Overcurrent protection: When the VM pin terminal detects that the voltage on the discharge MOSFET (Q2) is greater than the overcurrent protection threshold and remains so for longer than the overcurrent protection delay time, the DO terminal outputs a low level to turn off the discharge MOSFET (Q2), enters the overcurrent protection state, stops discharging, and prevents excessive current from damaging the battery and circuit. The overcurrent release condition is that the voltage on the VM pin terminal is less than the short circuit protection threshold (e.g., 0.400V) and exceeds the overcurrent recovery delay time (e.g., 60ms).

[0025] Temperature Protection: The battery temperature is detected by an NTC resistor connected to the OT pin. When the charging temperature reaches 50±5℃, the protection IC triggers the charging over-temperature protection, immediately turning off the charging MOSFET (Q3) and stopping the charging process to avoid safety issues caused by continued charging at high temperatures. When the discharging temperature reaches 70±5℃, the discharging over-temperature protection is triggered, turning off the discharging MOSFET (Q2) and stopping the discharging. After the charging over-temperature protection, if a load is connected and the voltage at the VM pin is greater than the discharge state judgment voltage (e.g., 7mV), the protection IC will shield the charging over-temperature protection, turning on the charging MOSFET (Q3). However, once the battery pack enters the discharging over-temperature protection or other reasons cause the discharging MOSFET (Q2) to turn off, the charging over-temperature protection will immediately deshield and turn off the charging MOSFET (Q3) again. The conditions for releasing the discharging over-temperature protection are that the temperature returns to within the discharging release temperature and the time exceeds the discharging temperature release delay, and at the same time, the voltage at the VM pin terminal is less than the short-circuit protection threshold and exceeds the load lockout release delay.

[0026] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A smart protection circuit for a lithium-ion battery, characterized in that, Includes CW1035BLAP, T3095UMOSFET, chip pins, surface mount capacitors, and surface mount resistors; The chip pins include VDD pin, VC1 pin, VC2 pin, VM pin, CO pin, DO pin, OT pin, and VSS pin; The CW1035BLAP protection IC has its VDD pin connected to the highest potential of the battery pack. The T3095U MOSFET includes a charging MOSFET and a discharging MOSFET. The charging MOSFET is connected between the charger and the battery pack, and its gate is controlled by the CO pin of the protection IC. The discharging MOSFET is connected between the battery pack and the load, and its gate is controlled by the DO pin of the protection IC. It can shut down the discharge output port during charging and can cut off the charging and discharging circuit under abnormal conditions. The surface-mount capacitors are connected across the VDD pin and the VSS pin respectively.

2. The intelligent protection circuit for a lithium-ion battery according to claim 1, characterized in that, The VC1 and VC2 pins are respectively connected to the positive terminals of each individual cell in the battery pack. The VM pin is connected to the discharge MOSFET to detect the discharge current. The CO pin is connected to the gate of the charging MOSFET to control the charging circuit. The DO pin is connected to the gate of the discharge MOSFET to control the discharge circuit. The OT pin is connected to the NTC resistor for temperature detection. The VSS pin is connected to the lowest potential of the battery pack.

3. The intelligent protection circuit for a lithium-ion battery according to claim 1, characterized in that, When the protection IC detects that the battery voltage reaches the overcharge protection voltage and the duration exceeds the overcharge protection delay time through the VC1 and VC2 pins, it outputs a high impedance state through the CO pin to turn off the charging MOSFET and stop charging. At the same time, the DO pin remains at a low level to close the discharge output port. Charging is restarted when all battery voltages are lower than the overcharge release voltage and the duration exceeds the overcharge release delay time.

4. The intelligent protection circuit for a lithium-ion battery according to claim 1, characterized in that, When the voltage of any cell is lower than the over-discharge protection voltage and exceeds the over-discharge protection delay time, the DO pin outputs a low level to turn off the discharge MOSFET and enters the over-discharge protection state. When the voltage of the VM pin is lower than the short-circuit protection threshold and exceeds the load lockout release delay time, the lockout is released and the normal state is restored.

5. The intelligent protection circuit for a lithium-ion battery according to claim 1, characterized in that, When the VM pin detects that the discharge MOSFET voltage is greater than the overcurrent protection threshold and remains so for longer than the overcurrent protection delay time, the DO pin outputs a low level to turn off the discharge MOSFET. The VM pin releases the overcurrent when the voltage is less than the short-circuit protection threshold and exceeds the overcurrent recovery delay time.

6. The intelligent protection circuit for a lithium-ion battery according to claim 1, characterized in that, The OT pin detects the battery temperature through an NTC resistor. When the charging temperature reaches the preset charging over-temperature protection threshold, the protection IC triggers the charging over-temperature protection, immediately shutting off the charging MOSFET and stopping the charging process. When the VM pin is connected to a load after the charging over-temperature protection and the voltage is greater than the discharge state judgment voltage, the protection IC shields the charging over-temperature protection and turns on the charging MOSFET. When the battery pack enters the discharge over-temperature protection or the discharge MOSFET is turned off for other reasons, the charging over-temperature protection is unshielded, and the charging MOSFET is turned off again.

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