Application analysis of lithium iron phosphate battery protection chip and lithium battery protection chip

Lithium iron phosphate battery protection chip When charging lithium iron phosphate batteries in series, each battery should be charged in a balanced manner, otherwise the performance and life of the entire battery group will be affected during use. However, the existing single-cell lithium battery protection chips do not contain the equalizing charge control function, and the multi-cell lithium battery protection chip equalizing charge control function needs to be connected to the CPU; it is realized through serial communication with the protection chip, which increases the complexity of the protection circuit. The degree and difficulty of design reduce the efficiency and reliability of the system, and increase power consumption. The lithium iron phosphate battery still needs to protect the board. When charging a group of lithium batteries in series, ensure that each battery is charged in a balanced manner, otherwise the performance and life of the entire group of batteries will be affected during use. Based on the design method of the equalization charging protection board for lithium iron phosphate battery packs, commonly used equalization charging techniques include constant shunt resistance equalization charging, on-off shunt resistance equalization charging, uniform battery voltage equalization charging, switched capacitor equalization charging, and step-down converter equalization Charging, inductance equalizing charging, etc. The use of lithium battery protection chip The analysis of the critical components in the working principle of the lithium iron phosphate battery protection chip: 1. IC: It is the core of the protection chip. First, the battery voltage is sampled, and then various instructions are issued through judgment. MOS tube: It is important for switching purposes. 2. Protect the chip to work normally: The MOS tube on the protection chip may be in the off state at the beginning. After the lithium iron phosphate battery is connected to the protection chip, the MOS tube must be triggered first, and the P+ and P- terminals must be triggered. There is an output voltage, the common method of triggering is to short-circuit B- and P- with a wire. 3. Protection chip overcharge protection: Connect a power supply higher than the battery voltage to P+ and P-, connect the positive pole of the power supply to B+, and connect the negative pole of the power supply to B-. After the power supply is connected, the battery starts to charge, the current direction is as shown in the figure The current of I1 shown starts from the positive pole of the power supply and flows through the battery, D1 and MOS2 to the negative pole of the power supply. The IC uses the capacitor to sample the value of the battery voltage. When the battery voltage reaches 4.25v, the IC sends a command to make the pin CO Low level, when the current starts from the positive pole of the power supply, it flows through the battery, D1, and reaches MOS2 because the gate of MOS2 is connected to CO and is also low, MOS2 is turned off, the entire loop is turned off, and the circuit plays a protective role . 4. Protection chip over-discharge protection: After connecting a suitable load to P+ and P-, the battery starts to discharge its current direction as I2, and the current flows from the positive pole of the battery through the load, D2 and MOS1 to the negative pole of the battery. MOS2 is short-circuited by D2); when the battery is discharged to 2.5v, IC samples and issues a command to turn off MOS1, the circuit is disconnected, and the battery is protected. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Lithium iron phosphate battery charging management chip and type analysis