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Pdsink: USB Power Delivery Sink library for embedded devices

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49 points zdw | 1 comments | 07 Dec 25 04:14 UTC | HN request time: 0.195s | source
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avidiax ◴[12 Dec 25 01:45 UTC] No.46239925[source]▶
I looked at adding USB-PD as a replacement for a 12V barrel-plug power supply in a recent project.

One big issue that came up (and killed the idea) is that if you are not battery powered, then putting a USB-C power input on your device that will only work if you can negotiate 12V+ with adequate current will just cause confusion. In my case, I don't think I could even boot to an error message on 5V.

Phones and the like don't have this issue, since they are still usable (charging slowly) on 5V, but can make use of higher voltages and currents to charge faster.

So I guess my question for the implementer is how booting & negotiating on 5V and then accepting higher voltage is likely to work in practice.

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1. rcxdude ◴[12 Dec 25 11:47 UTC] No.46243234[source]▶
The other issue with USB PD without a battery is that most chargers with multiple ports will drop the connection and renegotiate if any of the ports are plugged or unplugged (whether they need to in order to supply the new device or not).

(Relatedly, there's an empty niche in the market for a USB-C power bank that can act as a UPS: able to charge and discharge at the same time without interrupting the discharge port when the charge port is disconnected)