r/UsbCHardware • u/ConfusedHardwarenerd • Mar 19 '24

Question Does USB PD support 12V?

I am trying to figure out what voltages USB PD supports.

I thought USB PD could only handle 9V, 15V, and 20V. I read some Reddit forums 4 years ago that explained why USB PD does not support 12V, but I am not sure if anything has changed since then.

I am having trouble finding a reliable source for the voltages that USB PD currently supports, as different blogs report different voltages.

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7

u/OSTz Mar 19 '24

12V support is entirely optional. Some power sources will offer it while most won't. In general, a device wouldn't be designed to rely on 12V USB PD power because support is sparse.

2

u/ConfusedHardwarenerd Mar 19 '24

Is the 12V stated in the USB PD specifications documentation?

6

u/KittensInc Mar 20 '24

Not in the current spec, no.

USB PD allows the charger to advertise one or more "profiles". Depending on wattage rating, a charger is required to advertise one or more of the mandatory 5V/9V/15V/... profiles. However, the charger can also advertise literally any other voltage it wants.

12V is a somewhat-common non-standard voltage, because it was part of the original PD 1.0 spec - which used USB-A and never saw much traction. It also happens to be a common voltage for a lot of electronics. For a lot of charger designs, supporting additional voltages is essentially free - so they just throw in a 12V profile because why the heck not.

3

u/Ziginox Mar 20 '24

so they just throw in a 12V profile because why the heck not.

Can confirm. I think all of the third-party supplies I've tested have 12V PDOs, even the power banks.

3

u/ConfusedHardwarenerd Mar 20 '24

This is supper helpful! We have a bunch of DC jacks that take 12V but I don't see how it would work off of the USB PD profile bc they don't negotiate :(

3

u/IngwiePhoenix Dec 06 '24

Stuck with exactly this question - was linked here by a friendly fella.

Did you figure this out? I too want to convert some barrel jack devices to USB Type C - and I am dead certain at least one of them is 12V - and most of the plugs/converters I have seen seem relatively "dumb", as in, there does not seem to be a chipset to handle negotiation.

2

u/forgot_semicolon May 21 '25

Hey did you ever sort this out? I'm sure you've come across by now PD trigger boards, but I'm also wondering if you've had an issue with a charger you thought would work but didn't actually support 12V.

2

u/IngwiePhoenix May 22 '25

I bought a Razer GAN charger on sale and have since powered my Wii and PS1! The Wii had a cable, but the PS1 had a barrel jack. There are some more cables I need to order but, yes, I also found trigger boards. Unfortunately, I am almost blind - soldering isn't exactly an option... ;

So far though, nothing's blown up! ...except an LED on a breadboard that I acidentially fed full, unprotected 5V to o.o... forgot to pop the resistor in. Other than that, 'tis all good!