0
\$\begingroup\$

I have designed a simple PCB circuit board that is powered by either the 5V from a USB, or if a battery is plugged in, powered from a 3.3V and 5V regulator. I am no expert in electronics, but have attached my schematic below. enter image description here

I realized that if I remove and short D1 from the circuit and have it powered by USB, the 5V power from the USB will travel backwards through the 5V regulator and power the 3.3V regulator.

The regulators I am using are the LM1085ISX and the data sheet is attached. Datasheet. On page 12 of the datasheet it says that is has protection diodes that should prevent this reverse voltage, so I am a little confused as to why this is happening.

I know this probably isn't the ideal situation, but is it okay to have this reverse voltage flowing through the regulator, could it possibly damage it?

\$\endgroup\$

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.