MP2674 – CHARGE SYSTEM PROTECTION CIRCUIT

MP2674 Rev. 0.9

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9

11/8/2010

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time, the power FET is turned off. There is an

internal 4-bit binary counter monitoring the

occurrence of the battery over-voltage event. If

the battery over-voltage occurs 16 times, the

power FET is turned off permanently. Recycling

the input power will reset the counter and

restart the MP2674.

The resistor between the VB pin and the

battery,

Applications circuit, is an important component.

This resistor provides a current limit in case the

VB pin is shorted to the input voltage under a

failure mode. The VB pin leakage current under

normal operation is negligible to allow a

resistance of 200kΩ to 1MΩ being used.

Thermal Protection

The MP2674 monitors its own die temperature

to prevent thermal failures. When the internal

temperature reaches 150°C, the internal N-

channel power MOSFET is turned off. The IC

does not resume operation until the internal

temperature drops below 110°C.

Warning Indication Output

indicates a LOW signal when any of the four

protection events happens.

1. Input over voltage

2. Battery over voltage

3. Output over current

4. Thermal protection

To pull the

F L T

pin voltage low when fault, a

recommended 10kΩ to 200kΩ resistor should

be used as the pull up resistor.