The Pi itself can do that.Interesting that nowhere in the specs does it mention the 5v@3A https://datasheets.raspberrypi.com/powe ... -brief.pdf
It doesn't.
USB PD defaults to supplying 3A@5V unless both source and sink support it and negotiate something else.
All USB PD capable PSUs work this way.
It is a USB C thing (USB A doesn't have PD) but you'll only ever see a single voltage output at a time. (Well not quite, one of the CC pins is used to supply a small fixed voltage to allow PD negotiation before the main supply is configured. The other is used for the negotiation.)
Interesting indeed.
AIUI (and I may very well be wrong) that's what the PD spec says. I also recall a post from an RPL engineer on here saying 3A@5V is what happens with the official PSU when the sink doesn't do PD or doesn't want 5A@5V (or one of the other modes). Sorry I don't have the link to hand so may have misremembered.
Seemed a bit silly to me at the time given that everything is designed/rated for 5A and outside of a dead short devices only draw what they need.
Anyone got access to something that can sniff the PD negotiations and report back?
It's in the docs and someone made a script to decipher it.
I can't remember if they made the script available OR who it was..
usbpd_power_data_objects
Statistics: Posted by bensimmo — Sat Dec 20, 2025 9:56 pm