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Since the chemical composition of Li-ion is unstable, the batteries are in danger of leakage, explosion ignition when they are overcharged or over-current flows; therefore, a protection circuit is needed to protect the batteries from overcharge and over-current, and malfunctions caused by over-discharge. |
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Li-ion batteries are usually used as 1serial (cell phones) or 3serials(Note-PC). When they are charged based on the voltage of battery packs, cell voltages are to be different caused by the cell difference connected serial (capacity, charging state), which can cause overcharged cells. Protection circuit controls each cell voltage and charge/discharge so that certain cells are not overcharged (over-discharged) |
- Over charge detection protection circuit
- Over discharge detection protection circuit
- Over-current detection protection circuit
- Temperature rise
- Inner pressure raised, Inner cell (PTC(Temperature),Safety vent (Withstanding Voltage))
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| Control IC |
detects overcharge and over-discharge
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| Charge/discharge Switch |
MOSFET is generally used.
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| Temperature Fuse |
protects cells from overcharge during charge/discharge
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