Power supply for the rockpi

None of the newer USB C PD rev 2.0/3.0 have 12v rails only rev1.0 devices have.

5, 9, 15, 20v will be negotiated by the device.

There is absolutely no advantage to use a usb-c PD device unless you are sharing it amongst various devices that may change in voltage input range.
None at all if its going to be static for powering a RockPi4 unless you like that type of “wall charger”.

Also the regulation and efficiency on a computer power supply is likely to be much better and a gold (87 -90% efficiency) rated up to about 600 watt can be got for the price of the PSU you posted.

I read the PD specs for one of my projects, PD 2.0/3.0 didn’t completely drop 12V rail but made it optional, so there are new PD adapters still have it, e.g. the RavPower GAN 61W I posted above provides 12V rail. I used blank switch insert and PD adapters made some "wall outlet"s too. It’s such a relief when you have any charger in house charges any device you have.

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You can argue that one with wikipedia and the specs, not me.


No need to argue, it’s the specs. 12V is optional, but it’s supported by many vendors. In PD 2.0/3.0 specs (page 558):

In addition to the voltages and currents specified in Section 10.2.2, a Source that is optimized for use with a specific Sink or a specific class of Sinks May Optionally supply additional voltages and increased currents. See Section 10.2 for the rules that Shall apply to Optional

There are several times the specs use the optional 12V PDO as example (page 124 Higher Capability):

than vSafe5V (e.g. 12V) to provide full functionality, then the Higher Capability bit Shall be set.

Many major PD chip vendors support 12V PDO in their 2.0/3.0 compliant controllers, e.g. TI TPS65982

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You can not advise and forward an optional 12v that isn’t a fixed rail and dynamic on host negotiation and current usage.
Its fine for plugging into devices that allow variable voltage input like the RockPi4 but to use with devices expecting fixed rails, I am going to advise don’t do it.
If its a static fixed 12v it will work perfectly with the RockPi4 and also any device not PD expecting a fixed 12v rail.
People can not be purchasing devices on the off chance 12v is optionally offered and even then can not be sure it will remain static as voltage with PD is dynamically negotiated.
Also on page 588 where is 12V mentioned?

Glad to see that the two most helpful members (to me) have gotten together.:clap:
Great debate!
Once @stuartiannaylor receives his Rock Pi 4B, I’m sure that the two of you will be able to collaborate on an awesome dst.
I’ll be watching with the popcorn. :eyes:

But, while the two of you are on the subject, I would like your opinions on using the following for a solar charged UPS for the Rock Pi4B:

Dunno as most (I tinks) powerbanks can not charge when being used or vice versa and for some that puts a mocker on things.
But if that don’t bother and you are just going to switch over as the sun goes down then why not.

If you are solar and have battery storage you could just run from battery with the on board buck via standard solar gear.

PS it turned up and playing at the moment.

Thanks for the quick feedback. It’s description claims to be capable of charging while being used, so I’m hoping to use it instead of a battery (with or w/o solar charging).

Admittedly, its pricey. But, looks to me as though it covers all of the points we have been discussing.

PS. I’ll leave the two of you alone so as not to interrupt your fun.:sunglasses:

Didn’t look at the price but if it has that tick box that was the only drawback I could think of.
You can do the math on 50000maH with an approx watts, what you using for a screen?

Normally a TV screen, but VNC over wiffy while being on solar.