USB-PD - Explaining the Power Standard in the Raspberry Pi 5

RE: USB-PD - Explaining the Power Standard in the Raspberry Pi 5

wolfgangfriedrich — Tue, 03 Oct 2023 12:04:39 GMT

Over at the UsbCHardware subreddit is a good discussion about the RPI 5 PD implementation.

Pi 5 - 5V5A?! : r/UsbCHardware (reddit.com)

- W.

RE: USB-PD - Explaining the Power Standard in the Raspberry Pi 5

DAB — Sat, 30 Sep 2023 20:38:20 GMT

Once I saw the USB C spec and its 1000 pages, I knew we were in for a flurry of interesting applications.

RE: USB-PD - Explaining the Power Standard in the Raspberry Pi 5

beacon_dave — Sat, 30 Sep 2023 12:40:48 GMT

One area that may be of a concern with this future is what happens when things go wrong.

How is your equipment warranty going to hold out when a fault or incompatibility damages your expensive device that you have just plugged in to recharge. If the manufacturer didn't supply the charger/PSU along with the appliance, then they are likely to just walk away (or rather charge you for an out of warranty repair/replacement).

Ever since the increase in house fires due to counterfeit phone chargers, fire authorities have been urging consumers to only use the manufacturer supplied charger for the device whilst insurance companies have been walking away. If manufacturers are no longer supplying the charger with the device, then this could be an issue, otherwise you end up back to a drawer full of (more expensive) chargers again.

RE: USB-PD - Explaining the Power Standard in the Raspberry Pi 5

beacon_dave — Sat, 30 Sep 2023 11:17:02 GMT

"...is a standardized protocol and specification..."

The wonderful thing about standards is that there are so many to choose from.

I suspect that the problem will now be how far manufacturers are going to deviate from the standardized specification.

If I understand this correctly then sinks are supposed to function correctly with a USB PD source of the PDP rating or higher (but may have a reduced functionality with lower PDP rating).

So if a sink is rated with a PDP of 27W then ideally it should function correctly with ANY source being supplied with a PDP of 27W or higher for a 'just works' scenario.

However, if you take a look at the likes of the R Pi 5, it looks like you could end up with reduced functionality with a source of PDP 27W (and even with 45W and 50W) as the USB PD standard only requires 3A at 5V (see below). For full functionality in this case, you would need to use a non standard source that can deliver >3A.

To play nice with the standard then the likes of the R Pi 5 would have needed to use 3A at 9V in which case ANY source with a PDP of 27W or higher would have been suitable for full functionality.

In a lot of cases it probably doesn't matter, not everyone will need 1.6A at the USB ports on their R Pi 5, or won't notice if their device took twice as long to recharge but if every manufacturer starts doing this sort of thing, then it kind of defeats the point of having the standard and you will likely end up with a drawer filled with various chargers, but this time with the same connector type.

https://usb.org/sites/default/files/D2T2-1%20-%20USB%20Power%20Delivery.pdf

RE: USB-PD - Explaining the Power Standard in the Raspberry Pi 5

balajivan1995 — Sat, 30 Sep 2023 07:58:36 GMT

Latest microcontroller dev kits and iPhone all comes with type c connection. For once I'm glad standardization worked well.

RE: USB-PD - Explaining the Power Standard in the Raspberry Pi 5

Gough Lui — Sat, 30 Sep 2023 03:53:48 GMT

I wouldn't say it's the future. It's more the "now". Most phones use USB-C PD, many laptops can also use USB-C PD as (should) all USB-C devices that need more than 5V.

- Gough

RE: USB-PD - Explaining the Power Standard in the Raspberry Pi 5

dougw — Sat, 30 Sep 2023 02:14:17 GMT

This trend to use USB for power delivery is definitely already starting.