| 摘要 |
PURPOSE: A circuit for protecting a battery of a cellular phone is provided to configure circuits to be respectively separated, so as to protect the battery against over-current, overvoltage and overheating. Accordingly, the battery protection circuit does not break down wholly. CONSTITUTION: A battery(170) to which a thermistor(TH) sensing temperature is attached. An overvoltage/inverse-voltage protection circuit(120) receives power from an adapter(10) and protects the battery(170) against overvoltage and inverse-voltage of the adapter(10). The second CMOS(Complementary Metal Oxide Semiconductor)(C2) controls the continuity of power applied from the overvoltage/inverse-voltage protection circuit(120). An over-current protection circuit(130) receives and outputs output power of the second CMOS(C2), and outputs a control signal for preventing over-current charging of the battery(170). The second diode(D2) receives and outputs output power of the over-current protection circuit(130) and prevents current of a battery(170) from being leaked. A temperature protection circuit(150) receives output power of the second CMOS(C2) and output signals of the thermistor(TH), to output a control signal for preventing overheating of the battery(170). A charging control circuit(140) receives output power of the second diode(D2) to operate a cellular phone, outputs power for charging the battery(170), and receives the control signals of the over-current protection circuit(130) and the temperature protection circuit(150) to output an on/off control signal for charging the battery(170). The third CMOS(C3) receives the on/off control signal of the charging control circuit(140) to control the continuity of power applied from the charging control circuit(140) and charge the battery(170). And a constant-voltage/constant-current monitoring circuit(160) monitors voltage and current outputted from the charging control circuit(140) to the third CMOS(C3) to charge the battery(170), to output a control signal for turning off the second CMOS(C2) and cut off battery charging power if the monitored voltage and current are not constant-voltage and constant-current.
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