The main function of lithium battery protection board

　　Generally, it is required that the Control (IC) detects the voltage of the control cell and the working current and voltage of the charging and discharging circuit between -25 ℃ and 85 ℃. Under all normal circumstances, the C-MOS switch transistor is turned on, so that the cell and the protection circuit board are in normal working conditions. When the cell voltage or working current in the circuit exceeds the preset value of the comparison circuit in the control IC, the CMOS is turned off within 15-30ms (different control ICs and C-MOS have different response times), Close the discharge or charging circuit of the battery cell to ensure the safety of the user and the battery cell.

　　1. Overcharge protection and recovery

　　When the battery is charged and the voltage exceeds the set value VC (4.25-4.35V, specific overcharge protection voltage depends on the IC), VD1 flips and causes Cout to become low, T1 stops, and charging stops. When the battery voltage drops back to VCR (3.8-4.1V, specific overcharge protection recovery voltage depends on the IC), Cout becomes high, T1 conduction charging continues, and VCR must be less than a fixed value of VC to prevent frequent jumps.

　　2. Overdischarge protection and recovery

　　When the battery voltage decreases to the set value VD (2.3-2.5V, depending on the IC for overcharging protection) due to discharge, VD2 flips over. After a short delay, Dout becomes low, T2 stops, and discharge stops. When the battery is placed in charge, the internal or gate is flipped over, causing T2 to conduct again in preparation for the next discharge.

　　3. Overcurrent and short circuit protection

　　When the current of the circuit charging and discharging circuit exceeds the set value or is short circuited, the short circuit detection circuit acts, causing the MOS transistor to turn off and the current to be cut off.

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