I am using the BD9C401EFJ for 9V to 5V conversion (with enable pin pulled high). So - input = 9V and output = 5V.

I was just doing some experiments and saw that when I give no input, and I give 5V at the output side pin, strangely I am getting 5V on the input section. I thought that reverse flow of the current is not possible in a DC-DC regulator.


Generally reverse current can flow in this sort of circuit. Consider the block diagram from the datasheet:

The p-channel MOSFET will have 0V on the gate when input voltage is applied, so VIN and OUTPUT will be connected directly together. If it was a discrete MOSFET there would also be a body diode in parallel.

enter image description here

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.