MCP73831- Voltage Showing on VDD Pin When the Part is Not Being Powered Intentionally

Voltage on the STAT pin is causing a voltage to be present on the VDD pin, even when no power is applied to the device intentionally. Why does this happen?

This condition can put the device out of specification. It might be likely that MCP73831 is being back-biased through the body-diode on the high-side FET connected to the STAT pin.

Example Circuit Description:
The STAT output of MCP73831 device is connected to the MCLR pin of a 12F1572 device. Note that the MCLR function of the 12F1572 is disabled and the MCLR pin is internally pulled up to the VDD supply of the device(12F1572). With this configuration and the fact the MCP73831 STAT pin has a high-side driver (not included with the MCP73832), if the power is removed from the MCP73831 device while the PIC® is still powered, you could have a current path from the VDD of the PIC back to the VDD of the MCP73831.

The current path would be from the VDD of the PIC through the internal pull-up on the MCLR pin, through the body-diode of the high-side FET of the STAT pin, back to the VDD. This current path could cause the VDD of the MCP73831 to rise and cause inadvertent operation. The result is the voltage you see across the VDD and GND pins of the MCP73831 device.

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