Granted, you could just wire the power supply to be on all the time, but it is nice to be able to turn everything off. The plan was to use the always-on 5V standby rail to drive a pair of relays.

A computer power supply converts AC into multiple DC voltages. For example, 12 volts is commonly used for drives, while 3.3v and 5v are used by the chips and other motherboard components.

This handshaking approach supports voltage steps at 5V, 9V, 15V, 20V, and beyond for power outputs ranging from 0.5W to 240W. The newer USB Power Delivery Programmable Power Supply (USB PD PPS ...

The library's GPI is a highly configurable general-purpose input cell which features three selectable input modes, three selectable resistive termination options, and a wide supply range. The ...