[Paul] recently purchased an inexpensive USB power pack ... Now you can’t just hook up the 22 ohm resistor to a 5V power supply for the sake of keeping it on — that would draw 1.1watts ...

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 ...