General discussion • Re: Raspberry Pi5 USB-C PD

Has anybody tried to power the Pi-5 with a "third party" power supply which supports PD? And could those chargers actually supply the 5 amps that the Pi-5 needs? The question is, can the Pi-5 and a third party PD supported power delivery system actually "negotiate and agree" upon what they Pi-5 is asking for. Or does it even ask for it?

The Pi 5 does not "ask" as it is the sink. The source offers (advertises) available modes and the sink selects from the offered modes. As for this functioning, connect a Pi 5 to the official adaptor and note that the USB-PD negotiation results in 5V@5A. Plug the official power supply into something which perfers one of the higher voltage modes and note that tah da it gets the higher voltage mode. Liz recently mentioned that she charges her MacBook with the official power supply, but she might just be part of the conspiracy, as an insider and all that. Plug it into a dumb (standard USB) device and observe that it gets 5V@3V.

This does rest on believing that the USB-PD compliance stamped on the power supply and claimed by RPL is really a thing and that you can trust the claims made by the second higher voltage loving test sink. Maybe it is all alien mind control...

Alternatively don the oh so shiney protective headgear and offer alternate "theories".

I do not understand the reason for your cynicism. In any case, basically, because the 5volt-5amp, even though a PD mode, is an odd one, "most of" the PD supplies in the market does not actually support it. That is what i was trying to understand.

Sorry, it was perhaps in the way I read your question... Perhaps RPL should have been clearer that they made the following choices:

* to support an alternate and little used USB-PD voltage mode in their USB-PD source
* to not accept higher voltage modes, which means almost all other USB-PD sources will end up supplying 5v@3A

It has been confirmed that:

* the Pi 5 works just fine with the official supply
* it does negotiate and select the 5v@5A mode
* said supply works just fine with other USB-PD sinks
* the Pi 5 plays nicely with other USB-PD sources, and yes some exists with the 5v@5A mode
* they are following the USB-PD spec (which is freely available to download and read)

They have commented on why they decided to support the 5v@5A mode (they needed more power) and why they did not support the higher voltage mode (more cost, complexity, thermal issues, board real estate).

It is just that the same issue keeps churning and churning.

The options are simple:

* buy the official USB-PD supply (and it will just work)
* provide 5v@5A either via the USB C port or the appropriate GPIO pins, and set the over ride (and it will just work)
* use the quality 5v@3A Pi 4B USB C supply (and it will just work for most use cases)
* do something else and it may work

If you want to better understand USB-PD read the copious documentation available on it, including the official spec which is available for free download from https://www.usb.org/document-library/usb-power-delivery.

No Illuminati, free masons, or chickens were harmed in the creation of this post.

Statistics: Posted by bjtheone — Sun Apr 07, 2024 8:31 pm

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