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My Philips Hue light strip 30W / 12V power supply died, and I'm looking to replace it. The OEM replacement is big and heavy; meanwhile there are GaN-based USB-C wall plugs, that can deliver 30W / 12V, and that are available in very small form factor.

Is it possible to use one of these small computer charger USB-C adapters to power a 12V LED strip? And if so - how do I bridge from the USB-C to a constant 12V? I see one PCB that does the negotiation but it uses a pushbutton so every time it powers on I would have to select manually - in this scenario I need something that wakes up and immediately negotiates 12V continuous delivery.

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    \$\begingroup\$ Might be easier to just have a 12V 30W power supply. The USB-C chargers may not be intended for continuous 30W delivery as they might be intended for occasionally charging a phone. And if they are really small and cheap, the factory may have skimped on insulation and other safety and reliability aspects, while Philips would not. \$\endgroup\$
    – Justme
    Jun 21, 2022 at 20:13
  • \$\begingroup\$ 30W over USB-C means you'll be at 15V at least, so you'll need a 30W+ DC-DC converter in there as well as the power negotiation circuitry. \$\endgroup\$
    – vir
    Jun 21, 2022 at 20:36
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    \$\begingroup\$ you can get 12v fixed output triggers like the button-based one you found, keep looking. That said, they do often output 5v for a moment or two during startup (maybe up to ~800ms), which likely isn't an issue for dumb LEDs but might cause a problem with "smart strips". you could put something in front of it that doesn't close until the voltage is above 10v or something. heck, maybe just a 12v relay would suffice as the initial 5v "boot" period won't flip the armature. \$\endgroup\$
    – dandavis
    Jun 21, 2022 at 21:03
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    \$\begingroup\$ Thanks for these - a few notes: 1. The USB-C I have supports 12v x 2.5a so no stepdown required. 2. The reason I'm looking to use this USB-C is because they are now available in such small form factor. I suspect the GaN technology will eventually be used for LED drivers but I haven't been able to find one yet? \$\endgroup\$
    – Spencer Greene
    Jun 21, 2022 at 23:04

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The device you're describing is called "USB trigger" or "USB power decoy" - a small, low-cost, USB device that does nothing else but negotiate voltage.

The pushbutton-configurable one you've found are rarer and more expensive, intended for tinkering rather than permanent operation. You'll need a fixed 12V flavor.

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A quick search on Amazon yields this 12V 30W LED power supply. For only $15, why not? I would definitely consider replacing your power supply with something at least advertised as doing exactly what you want. You could run into issues with trying to get a constant 30W output from a USB-C charger. I could be wrong, but they probably are not designed (for the most part) to give the full 30W constantly. I imagine you would end up having to add a few more components (like a DC-DC converter as @vir said) to get the USB-C to work for your application.

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  • \$\begingroup\$ Thanks - that is a good option but it is still 7" x 1" x 0.75", and I've got a relatively small space. This USB-C plug measures 1" x 1" x 1.5" so if I can get it to work - even with an external adapter - it could be a win. \$\endgroup\$
    – Spencer Greene
    Jun 21, 2022 at 23:13

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