CR1625 battery

Briefly describe the composition and working principle of CR1625 battery protection board

1. Control IC, 2. Switch tube, and some micro-capacitors and micro-resistors. The purpose of control IC is to protect the battery. If the protection conditions are met, the MOS will be controlled to open or close (such as the battery reaches overcharge, over-discharge, short circuit, overcurrent, etc. protection conditions). The purpose of MOS tube is the switch, which is controlled by the control IC.

The reason why lithium-ion batteries (rechargeable) need protection is determined by their own characteristics. Since the material of lithium-ion batteries themselves determines that they cannot be overcharged, over-discharged, over-current, short-circuited, and charged and discharged at ultra-high temperatures, lithium-ion battery CR1625 battery components always appear with a delicate protection board and a current fuse. The protection function of lithium-ion batteries is usually completed by the protection circuit board and PTC. 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 at all times in an environment of -40℃ to +85℃.

Working principle of protection board

1. Overcharge protection and overcharge protection recovery

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

2. Over-discharge protection and over-discharge protection recovery

When the battery voltage drops to the set value VD (2.3-2.5V, the specific overcharge protection voltage depends on IC) due to discharge, VD2 flips, and after a short delay, Dout becomes low level, T2 is cut off, and discharge stops. When the battery is placed in charging, the internal OR gate is flipped to make T2 turn on again to prepare for the next discharge.

3. Overcurrent and short circuit protection

When the circuit charge and discharge current exceeds the set value or is short-circuited, the short circuit detection circuit will be activated, turning off the MOS tube and cutting off the current.

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