Principle of Operation for Iron-Lithium Ion Battery Protection IC:

Lithium iron phosphate ion battery circuits are equipped with overcharge protection, over-discharge protection, overcurrent protection, and short-circuit protection functions. Understanding the fundamental working principles of these protection ICs is essential for better designing lithium iron phosphate ion battery packs, and even assisting the quality department in analyzing abnormal batteries or circuits. The need for protection in lithium iron phosphate ion batteries (rechargeable) is determined by their inherent characteristics. Since the material of lithium-ion batteries itself determines that they cannot be overcharged, over-discharged, over-cycled, short-circuited, or subjected to excessive temperatures during charging and discharging, lithium-ion battery components are always accompanied by a sophisticated protection board and a current fuse.

Lithium iron phosphate battery protection functions are typically achieved through the collaborative efforts of protection circuit boards and PTC current devices. The protection board consists of electronic circuits that monitor the cell voltage and the charging/discharging current circuits within the temperature range of -40℃ to +85℃, controlling the on/off of the current circuit in a timely manner; the PTC prevents the battery from experiencing severe damage in high-temperature environments.

1. Introduction to Key Components in the Working Principle of IC Protection: IC: It serves as the core of the protection IC, first sampling the battery voltage and then issuing various commands after discrimination. MOS Tube: It plays a crucial role as a switch.

2. Ensuring IC Normal Operation: The MOSFET on the protection IC may initially be in the off state. After connecting the battery to the protection IC, it is necessary to trigger the MOSFET for output voltage at the P+ and P- terminals. The common method to trigger it is to short B- and P- using a wire.

3. IC Overcharge Protection: Connect a power supply higher than the battery voltage to P+ and P-. The positive terminal of the power supply is connected to B+, and the negative terminal is connected to B-. After connecting the power supply, the battery begins to charge. The current flows in the direction of I1 as shown in the diagram, starting from the positive terminal of the power supply, passing through the battery, D1, and MOS2 to the negative terminal of the power supply (at this time, MOS1 is short-circuited by D1). The IC samples the battery voltage value through a capacitor. When the battery voltage reaches 4.25V, the IC issues a command, making the pin CO low. At this point, the current starts from the positive terminal of the power supply, passes through the battery, D1, and reaches MOS2. Since the gate of MOS2 is connected to CO and also low, MOS2 is turned off, and the entire circuit is disconnected, serving as a protective function.