Other projects • Re: Alternate power source-100W USB-C connection

@jamesh:

Not me. I just have a better than average understanding of tech and the ability to read and understand datasheets and specs.

And an understanding of where the burden of proof lies.

I also find inaccurate information offered in the guise of "help" to be worse than useless.


@rin67630 :

1. This is no longer about the thread title. It's about your inaccurate statements and obvious misunderstandings.

2. [...] 10W (2A-5V), and would do that by increasing the output voltage above 5V up to 20V.

   That's incorrect. 15W not 10 and current can be increased to 5A at any voltage in the valid range. (and the latest spec allows more than 20v). Providing, of course, that source, sink, and cable(s) allow it.

3. Obviously the Raspberry Pi neither delivers the handshake, nor can deal with more than 5,5V.

   Incorrect conclusion. The handshake fails. Though you are correct that that the Pi cannot accepct more than 5v (+/- a few percent)

4. It probably just would crash.

   No it wouldn't. See viewtopic.php?t=377395#p2258337

5. The point was -and you confirmed it- that a raspberry Pi can not use more than 15W from a large PD power supply.
   So your offensive last sentence is just unapplicable.

   I didn't and it isn't: viewtopic.php?t=377395#p2258942

6. After all, why would RPL have added PD to the Pi 5 and produced a PSU with PD and that mode if the Pi doesn't use it?

   Has it? The RPI has a USB-C connector and cannot negociate anything above 5V. Calling that "PD" is an abuse.
   It just uses what a Power supply can deliver at 5V and if that Power supply is really PD compliant that's 15W.
   
   What RPI produces, which can supply more than 3A at 5V ist NOT PD compliant.

   That's just plain wrong:
   https://www.raspberrypi.com/products/raspberry-pi-5/
   https://www.raspberrypi.com/products/27w-power-supply/
   And the documents I linked to above.

7. Where in the PD specification does it say that ? Page number and section please .

   That's not what I meant

   It is what you said however.

8. , but every regular PD power supply will expect to deliver higher voltages as soon as more power is required.

   They don't expect anything. They advertise what the can supply and the sink picks one.

9. You can't put 5A on regular PD cables, they are not designed for that intensity.

   Doesn't apply when the PSU has a captive cable. But yes. That's why emarked cables exist and why PD is a negotiation betwen two or more devices.

10. Under the line it's simple. Most PD pover supplies will only work in a very limited way with a RPI 5.
    It's better not to use them.

    There is no problem using them. Just manage you expectations. 100W PDP does not mean 100W to every sink.

11. If a "large PD power supply" offers a 5A, 5V mode a Pi 5 will use it. ... so many PSUs of any wattage do not include it.

    Many? Which one -excepted the RPI's own one- does it too? Can you mention another one?
    Back to the threads title: Alternate power source-100W USB-C connection.That is the decisive point.

    I said "many" as I am not in the habbit of making unsupported sweeping generalisations. Plus saying "all" or "no" would most definitely be inaccurate. Persoanlly speaking, I don't have any non-RPL PD PSUs that suport 5A@5V but that by no means indicates that such things do not exist. "Absense of evidenve is not evidence of absence."
12. I'm guessing that you still haven't read and understood the documents I pointed you at.
13. Care to dig your hole any deeper?

Statistics: Posted by thagrol — Thu Oct 10, 2024 9:12 am

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