[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 ...

USB 3.0 stepped power output up to 5V at 0.9A, giving us a more tolerable 4.5W. Some USB 3.0 ports that are designed for charging can supply 5V at 1.5A, or up to 7.5W. Though these numbers still ...

Also, why was the output 4.7-5V, and why did my scope say 5.5V ... Check out a much more thorough analysis of this and pretty much every USB power supply cube by [Ken Shirriff].

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 ...