Do many desktop and laptop computers provide 10W or more over USB?

Question

As far as I understand, USB defines two additional power-related standards - Battery Charging and Power Delivery. Both of these allow for current above the standard 500mA with 5V, and PD offers higher voltage too.

What I couldn't find is how often these standards are implemented in laptops and desktop PCs, and how these trends have changed over the years. Manufacturers don't seem to mention it in specs either.

Are there any statistics or at least anecdotal info available about this?

Answer 1

In most mainstream desktop PC, especially in DYI sector, USB port power is simply derived from main PSU, from its +5VSB (STANDBY) voltage. The power distribution is fairly simple, all ports are "ganged" with resettable fuses (polyfuses), one, or per port basis. In this case the power is limited by PSU capability of +5VSB rail, which must be above 2A per ATX12V standard. Since the +5VSB rail is also responsible for functionality of power on-off buttons and sleep functions of PCs, overloading USB can have consequences.

In more reputable PC the USB ports might have controlled high-side power switches with current cut-off limit. The ports are usually paired, so the provider capability is about twice the USB standard. Still the power is limited by PSU. In most cases the VBUS power stays up when PC is turned to sleep/hibernate, so keyboard or mouse will be able to wake it up.

Laptops are more sophisticated devices. In the portable space they tend to limit the VBUS with better restrictions. To avoid accidental battery drainage in case of USB device misbehaving in terms of low-power management laptops use so-called "cold SUSPEND" when off, as opposite to "hot SUSPEND" as in regular desktop PC, although some laptops provide at least one "charging port" with usually undisclosed charger signature.

The more sophisticated Battery Charging (BC), Power Deliver (and some other "quick charging" schemas) are usually off-sourced to various docking stations. BC is largely dead, and PD is just taking off. Some docking devices offer a more sophisticated approach, by sequentially trying different port signatures (apple, China/DCP, BC1.2, boit sure about QCOMM QC), but it is a tricky deal. Type-C together with PD are supposed to take over all this, but...