Please re-read what I wrote and you quoted. Clearly, the 1A6 requirement for downstream USB is a design goal.Err, no. Only if you want the full 1.6A (8W) for downstream bus powered USB devices. If you can work with 600mA (3W) or don't need the full 17W for the PI and HATS, 5v/3A (15W) is fine. FWIW, I've booted lightly loaded Pi5 off an 8W supply - the USB port of another Pi5.The Pi5 clearly needs more than 15W to implement its design goals with the available (affordable) silicon.
Of course, you can use any decent USB-PD supply if you are not exceeding the 3A it will provide, but also, of course, 3A (0A6 downstream) was not an adequate specification for use with an unspecified USB load. (Given the USB spec, I'm not sure that 1A6 across four downstream sockets is really suitable either, but that is a specified limit that most of us can work with.)
Yeah. you're right. I'm wrong. Sorry.
As for the USB spec, my understanding is that the onus is on the device to limit its current use (<=100mA until after enumeration and the host has said it's OK to draw more) not on the host to supply any particular amount beyond 100mA. But I could be wrong there too and things could have change since I last looked.
Statistics: Posted by thagrol — Thu Jan 02, 2025 9:35 pm
