I'm currently creating a small device to operate on a CR2032 battery when it is disconnected and a USB power when it is connected. I want the device to be powered by USB when it is connected, without any interruption in the power feed. So my question is: how to switch from battery to USB one the device is connected?
I thought to connect two diodes and a PNP transistor to turn the power based on the battery as soon as the USB is connected. But I wonder if this circuit consume many current when the USB is disconnected (consumption must be very low)?
If you have any solution which will consume less current please tell it to me !