Reversed polarity on step-down regulators

Hi there,

I’m pretty new to electronics and have a basic question I could use some help with.

I’m powering a small Arduino project using batteries that range from 6 to 7.2 volts. Specifically I am delivering power to a Lolin D1 Mini through its 5 volt Vin pin. So I am looking at Pololu’s step-down regulators to make sure I don’t deliver too many volts when my batteries are freshly charged.

My concern is that when I program the D1 Mini via USB, the Vin pin gets powered, which means the regulator will have a positive voltage on its Vout pin. The regulator’s GND pin will be connected to the D1 Mini’s, but the regulator’s Vin pin will not be connected to anything because I won’t be using USB and the batteries at the same time. So I think essentially a circuit will be created with positive voltage applied to the regulator’s Vout and passing through to GND.

Is this something that could damage a D24V10F5? What about one like D24V22F5 that advertises reverse voltage protection?

Happy to provide any more information that may be useful…thank you!


The reverse voltage protection feature on our regulators protects the board in the event that the input power is connected with reversed polarity (i.e. connecting the negative lead on your power source to VIN and the positive lead to ground); it does not protect against power being applied to their output pins like you’re describing, and we do not characterize them for that. You can find some more information on the topic in this post by Jan.


Thank you for the clarification, that old post by Jan was very helpful.