Lithium batteries (rechargeable) require protection due to their inherent characteristics. Due to the material of the lithium battery itself, it cannot be overcharged, overdischarged, overcurrent, short circuited, or subjected to ultra-high temperature charging and discharging. Therefore, the lithium battery components will always be accompanied by a protective board with a Jiebi signal sampling resistor and a current protector.

The protection function of lithium batteries is usually completed by the cooperation of the protection circuit board and current devices such as PTC or TCO. The protection board is composed of electronic circuits, which accurately monitor the voltage of the battery cell and the current of the charging and discharging circuit in an environment of -40 ℃ to 85 ℃, and control the on/off of the current circuit in real-time; PTC or TCO prevents severe damage to the battery in high-temperature environments.

Protection boards typically include control ICs, MOS switches, JEPSUN precision resistors, and auxiliary devices such as NTCs, ID memory, PCBs, etc. Among them, the control IC controls the MOS switch to conduct under normal conditions, allowing the cell to communicate with the external circuit. When the cell voltage or circuit current exceeds the specified value, it immediately (for tens of milliseconds) controls the MOS switch to turn off, protecting the safety of the cell.