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by ilyt 1108 days ago
There is, just not for "AC wall voltage". It could simply drop the voltage and expect the other device to say start limiting current when it goes 5% or more below nominal voltage. Akin to how MPPT works on solar chargers

It "just" requires both sides to support that. Which won't happen as we already have USB-C if you want to negotiate the power usage.
1 comments
rektide 1108 days ago
We could invent other signaling strategies too. Maybe we lower the voltage by 5% as a "low" signal. Now we can yell at the device in binary, and more explicitly spell out the conditions.

Maybe the source sends S-O-S in Morse code. Maybe it sends a requested max power.

We can invent signalling strategies to communicate yes. EV chargers use HomePlug Green for example to commitcate. This could be consumerized & put into all devices, used to perform negotiations. https://en.m.wikipedia.org/wiki/HomePlug

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ilyt 1108 days ago
If we wanted to go entirely analog just simple CV/CC on the power source side (meaning "keep constant voltage up till max amps, then start dropping voltage) + MPPT-like controller on the sink is enough. That's easy enough to be done on off-the shelf chips.

>We can invent signalling strategies to communicate yes. EV chargers use HomePlug Green for example to commitcate. This could be consumerized & put into all devices, used to perform negotiations. https://en.m.wikipedia.org/wiki/HomePlug

I'm kinda surprised that's relatively rare approach, in-band communication like that saves 2 wires so would technically allow USB-C to get extra 20% power boost over same connector. I think I saw it used in some solar stuff to coordinated various devices of same manufacturer.

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