@brossingo It's unclear if you mean voltage supplied BY the device, or voltage supplied TO the device. If you're using USB, the voltage is obviously supplied by an external device (PC, power supply...) TO the device, and the device can't change that. If you want to use a different voltage, your probably want to use the battery connector instead, though it depends a lot on what actual voltage you can feed the device and a lot of other considerations. Could you give more details about what exactly you are trying to achieve?

@robert-hh good solution, thanks.