Two string lithium battery protection circuit

Abstract

This utility model discloses a protection circuit for two lithium batteries, including a battery protection chip SC5550ABBE. The positive and negative terminals B+ and B- of the two lithium batteries are connected for charging via positive and negative charging terminals P+ and P-, respectively. A charge / discharge MOSFET is connected in series on the negative charging line. The battery protection chip SC5550ABBE is connected to collect the voltage of two cells from the two lithium batteries in each string and controls the on / off state of the charge / discharge MOSFET. This utility model's two-string lithium battery protection circuit uses the highly integrated lithium-ion or lithium polymer battery protection chip SC5550ABBE. This chip provides overcharge, over-discharge, overcurrent, open circuit, and overtemperature protection for the battery pack, as well as equalization functions, and supports cascading. By using this protection chip, the safety and reliability of lithium batteries can be effectively improved, and the battery life can be extended.

Description

Technical Field

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

[0002] Lithium-ion batteries are widely used in various electronic devices due to their advantages such as high energy density, long lifespan, high rated voltage, high power handling capacity, low self-discharge rate, light weight, and strong adaptability to high and low temperatures. However, lithium-ion batteries are susceptible to overcharging, over-discharging, overcurrent, short circuits, and abnormal temperatures during use. These factors can lead to decreased battery performance, shortened lifespan, and even safety hazards. Therefore, designing an efficient and reliable lithium-ion battery protection circuit is particularly important.

[0003] Traditional lithium battery protection circuits typically use discrete components to implement functions such as overcharge, over-discharge, overcurrent, short circuit, and temperature protection. However, this design approach suffers from problems such as circuit complexity, high cost, and low reliability. With the development of integrated circuit technology, highly integrated lithium battery protection chips have gradually become the mainstream. These protection chips can integrate multiple protection functions within a single chip, which not only simplifies circuit design but also improves the reliability and efficiency of protection. Utility Model Content

[0004] The purpose of this invention is to provide a protection circuit for two lithium batteries, which effectively improves the safety and reliability of lithium batteries and extends their service life.

[0005] The technical solution of this utility model is:

[0006] The circuit includes a battery protection chip SC5550ABBE. The positive and negative terminals B+ and B- of the two lithium batteries are connected to the positive and negative charging terminals P+ and P- respectively for charging. A charge / discharge MOSFET is connected in series on the negative charging line. The battery protection chip SC5550ABBE is connected to collect the voltage of two cells of the two lithium batteries and is connected to control the on / off state of the charge / discharge MOSFET.

[0007] Preferably, when the charging voltage of a single cell in the two lithium battery strings reaches 4.175V, the charging MOSFET is disconnected; when the discharging voltage of a single cell reaches 2.8V, the discharging MOSFET is disconnected.

[0008] Preferably, the battery protection chip SC5550ABBE is also connected to a temperature detection module to detect the temperature of the lithium battery and control the charging and discharging to stop when the temperature exceeds the set temperature.

[0009] Preferably, each of the charging and discharging MOS transistors is composed of multiple MOS transistors connected in parallel.

[0010] Preferably, a current acquisition circuit is connected in series on the negative charging line to acquire the current signal and send it to the battery protection chip SC5550ABBE, which performs overcurrent protection.

[0011] Preferably, a three-terminal fuse is connected in series on the positive charging line, and the two lithium battery protection circuits also include a secondary protection chip U2. The secondary protection chip collects the voltage of the two battery cells and controls the on / off state of the three-terminal fuse.

[0012] The advantages of this utility model are:

[0013] This utility model presents a two-string lithium battery protection circuit, employing a highly integrated lithium-ion or lithium polymer battery protection chip, SC5550ABBE. This chip provides overcharge, over-discharge, overcurrent protection during charging and discharging, open circuit protection, overtemperature protection during charging and discharging, and equalization functions for the battery pack, and supports cascading. Using this protection chip can effectively improve the safety and reliability of lithium batteries and extend their lifespan. Attached Figure Description

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0015] Figure 1 This is a schematic diagram of the two-string lithium battery protection circuit of this utility model. Detailed Implementation

[0016] like Figure 1 As shown, the two-cell lithium battery protection circuit of this utility model includes a battery protection chip SC5550ABBE. The positive and negative terminals B+ and B- of the two-cell lithium batteries are connected to the positive and negative charging terminals P+ and P- for charging, respectively. A charge / discharge MOSFET is connected in series on the negative charging line. The battery protection chip SC5550ABBE is connected to collect the voltages B1 and B+ of the two cells of the two-cell lithium batteries and is connected to control the on / off state of the charge / discharge MOSFET.

[0017] The charging and discharging MOSFETs are each composed of multiple MOSFETs Q1-Q21 connected in parallel. When a single cell of the two lithium battery strings is overcharged to 4.175V, the charging MOSFET is disconnected; when a single cell is undercharged to 2.8V, the discharging MOSFET is disconnected. When the protection board is operating normally, the power supply CC / CV charges. When each cell reaches 4.175V, the CO port output level of the SC5550ABBE changes from the normal high level to a low level, cutting off the MOSFET. When each cell discharges to 2.8V, the DO port output level of the SC5550ABBE changes from the normal high level to a low level, cutting off the MOSFET, thus providing protection.

[0018] The battery protection chip SC5550ABBE is also connected to a temperature detection module (NTC1, R4) to detect the temperature of the lithium battery. When the temperature exceeds the set temperature, it controls the charging and discharging to stop.

[0019] A current acquisition circuit (R12, R13, RS1-RS7) is connected in series on the negative charging line to acquire the current signal and send it to the battery protection chip SC5550ABBE. The battery protection chip SC5550ABBE performs overcurrent protection.

[0020] Three three-terminal fuses F1-F3 are connected in series on the positive charging line. The two lithium battery protection circuits also include a secondary protection chip U2. The secondary protection chip collects the voltage of the two battery cells and controls the on / off state of the three-terminal fuses.

[0021] This utility model presents a two-string lithium battery protection circuit, employing a highly integrated lithium-ion or lithium polymer battery protection chip, SC5550ABBE. This chip provides overcharge, over-discharge, overcurrent protection during charging and discharging, open circuit protection, overtemperature protection during charging and discharging, and equalization functions for the battery pack, and supports cascading. Using this protection chip can effectively improve the safety and reliability of lithium batteries and extend their lifespan.

[0022] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All modifications made in accordance with the spirit and essence of the main technical solution of this utility model should be included within the scope of protection of this utility model.

Claims

1. A protection circuit for two lithium batteries, characterized in that, The system includes a battery protection chip SC5550ABBE. The positive and negative terminals B+ and B- of the two lithium batteries are connected to the positive and negative charging terminals P+ and P- respectively for charging. A charge / discharge MOSFET is connected in series on the negative charging line. The battery protection chip SC5550ABBE is connected to collect the voltage of the two cells of the two lithium batteries and to control the on / off state of the charge / discharge MOSFET.

2. The two string lithium battery protection circuit of claim 1, wherein, When a single cell of the two lithium batteries is overcharged to 4.175V, the charging MOSFET is disconnected; when a single cell is undercharged to 2.8V, the discharging MOSFET is disconnected.

3. The two string lithium battery protection circuit of claim 1, wherein, The battery protection chip SC5550ABBE is also connected to a temperature detection module, which detects the temperature of the lithium battery and controls the charging and discharging to stop when the temperature exceeds the set temperature.

4. The two string lithium battery protection circuit of claim 2, wherein, The charging and discharging MOSFETs are each composed of multiple MOSFETs connected in parallel.

5. The two string lithium battery protection circuit of claim 1, wherein, A current acquisition circuit is connected in series on the negative charging line to acquire the current signal and send it to the battery protection chip SC5550ABBE. The battery protection chip SC5550ABBE performs overcurrent protection.

6. The two string lithium battery protection circuit of claim 1, wherein, A three-terminal fuse is connected in series on the positive charging line. The two lithium battery protection circuits also include a secondary protection chip U2. The secondary protection chip collects the voltage of the two battery cells and controls the on / off state of the three-terminal fuse.

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