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LD39200PUR Reverse current protection not working as expected


We are using the LD39200PUR as a regulator to step 5V down to 4.3V for a battery based system.

The datasheet says the product incorporates reverse current protection to prevent current leaking from the output to the input but it is not functioning in the way I would expect.


On the input side we have a USB connection with 5V, on the output side we have either 4.3V regulated or the voltage of the battery (The system switches to battery power when the USB is removed).

When I remove the USB however, the voltage at the output pin is available on the input pin and I have been able to draw over 300mA from the input pin without issue. The section from the datasheet reads " Moreover it is used to avoid the reverse current to flow from the output pin to the input one, when other power supplies, providing a voltage higher than the input voltage, are connected to the output pin." In my case I have a power supply (battery) on the output pin, and nothing connected to the input pin so should satisfy the condition stated.


Is someone able to help me understand why the function is working as intended