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> I couldn't find a USB-C SATA adaptor that used PD to power the disk Would this even be possible? I assume some devices can do PD both ways (for charging and

> I couldn't find a USB-C SATA adaptor that used PD to power the disk Would this even be possible? I assume some devices can do PD both ways (for charging and as a source). But if that’s even possible, I’d imagine it to be rare. I’d love to know the case from someone who knows more.

seba_dos1 4y ago
That sounds just like the simplest case of a PD-powered peripheral. Why would you even ask if it's possible? The problem is that not many USB-C data ports do PD, and even when they do, they may not necessarily provide the voltage required by such disk.
- mbreese 4y ago
  I mainly think of PD ports in reference to charging, not data. I know dock PD ports do both, so I know data+PD is possible, but can my laptop's USB-C port support PD in both directions (charging and powering a peripheral)?. That's my main question -- most of my exposure to PD is with charging only... not powering peripherals. I know I can charge my phone with my laptop, but I've never looked to see how fast it is charging. And more importantly, what do available chips support? How easy is it to get chips that support PD + data? This isn't my area of expertise, so I was hoping someone would be able to say -- Yes, it's possible, I do this all the time. Or -- it's theoretically possible, but not widely supported, so no one does it.
  - seba_dos1 4y ago
    > but can my laptop's USB-C port support PD in both directions (charging and powering a peripheral)?. Two of the USB-C ports of my Dell XPS 13 9380 provide 5A/3A over PD, and the third one provides 5A/1.5A. All of them can negotiate both sink and source PD contracts. If your laptop can be charged via USB-C port and you can attach peripherals to the same port, it's almost certain that it can negotiate a source PD contract as well. That doesn't automatically mean you'll get more than 5V though, so such PD port may still be useless for powering a disk drive enclosure without additional voltage regulation.
    - Kirby64 4y ago
      I'm assuming you mean 5V/3A and 5V/1.5A. If so, that is explicitly NOT PD. USB-C supports 3A and 1.5A purely by setting resistor values on the CC pins, and does not require the BMC PD negotiation protocol. Many PD controllers support this for 'sourcing' (5V/1.5A or 5V/3A) natively, since it's a common use case for laptops.
      - seba_dos1 4y ago
        No, this is 5V/3A and 5V/1.5A as communicated via PD 3.0. In this case you can achieve the same result without PD (well, almost - you still need it for role swap), but that's not what I was talking about.
        Kirby64 4y ago
        What scenario would your laptop be providing power (being the source), while simultaneously being the receiver of data (data sink)? Not sure I see the use case for that, regardless of whether you can achieve 5V/3A over PD.
        seba_dos1 4y ago
        You need PD for power role swap, for example when (un)plugging a power supply to already connected USB-C hub. You also need PD for alt-mode negotiation. You can negotiate a 5V/3A contract to, let's say, power a DisplayPort/HDMI dongle - that won't work by simply signaling 1.5A or 3A with a resistor.
        Kirby64 4y ago
        Understood you need PD for alt modes, that's a given. I never thought about the scenario where you have a powered USB hub and you switch from powering it via a brick to powering it via your laptop... interesting, and actually very reasonable scenario. I guess given you have PD already built-in, it's not too hard to integrate that functionality either.
pestatije 4y ago
Wouldn't a powered USB hub do this?
OJFord 4y ago
Someone else brought that up, I don't really know, but my phone says it's 'charging rapidly' if I plug it into my laptop, so I just assumed it'd be possible.
derkades 4y ago
Newer phones and laptops can do PD both ways. It's a weird feeling at first to charge a laptop from a mobile phone, but it works!
sowbug 4y ago
You might be misunderstanding the idea. "used PD to power the disk" means the adapter used PD to obtain electricity, and then used that electricity to power the disk drive via the drive's normal power terminal. The disk drive still wouldn't know anything about USB Power Delivery.

seba_dos1 4y ago

That sounds just like the simplest case of a PD-powered peripheral. Why would you even ask if it's possible? The problem is that not many USB-C data ports do PD, and even when they do, they may not necessarily provide the voltage required by such disk.

mbreese 4y ago
I mainly think of PD ports in reference to charging, not data. I know dock PD ports do both, so I know data+PD is possible, but can my laptop's USB-C port support PD in both directions (charging and powering a peripheral)?. That's my main question -- most of my exposure to PD is with charging only... not powering peripherals. I know I can charge my phone with my laptop, but I've never looked to see how fast it is charging. And more importantly, what do available chips support? How easy is it to get chips that support PD + data? This isn't my area of expertise, so I was hoping someone would be able to say -- Yes, it's possible, I do this all the time. Or -- it's theoretically possible, but not widely supported, so no one does it.
- seba_dos1 4y ago
  > but can my laptop's USB-C port support PD in both directions (charging and powering a peripheral)?. Two of the USB-C ports of my Dell XPS 13 9380 provide 5A/3A over PD, and the third one provides 5A/1.5A. All of them can negotiate both sink and source PD contracts. If your laptop can be charged via USB-C port and you can attach peripherals to the same port, it's almost certain that it can negotiate a source PD contract as well. That doesn't automatically mean you'll get more than 5V though, so such PD port may still be useless for powering a disk drive enclosure without additional voltage regulation.
  - Kirby64 4y ago
    I'm assuming you mean 5V/3A and 5V/1.5A. If so, that is explicitly NOT PD. USB-C supports 3A and 1.5A purely by setting resistor values on the CC pins, and does not require the BMC PD negotiation protocol. Many PD controllers support this for 'sourcing' (5V/1.5A or 5V/3A) natively, since it's a common use case for laptops.
    - seba_dos1 4y ago
      No, this is 5V/3A and 5V/1.5A as communicated via PD 3.0. In this case you can achieve the same result without PD (well, almost - you still need it for role swap), but that's not what I was talking about.
      - Kirby64 4y ago
        What scenario would your laptop be providing power (being the source), while simultaneously being the receiver of data (data sink)? Not sure I see the use case for that, regardless of whether you can achieve 5V/3A over PD.
        seba_dos1 4y ago
        You need PD for power role swap, for example when (un)plugging a power supply to already connected USB-C hub. You also need PD for alt-mode negotiation. You can negotiate a 5V/3A contract to, let's say, power a DisplayPort/HDMI dongle - that won't work by simply signaling 1.5A or 3A with a resistor.
        Kirby64 4y ago
        Understood you need PD for alt modes, that's a given. I never thought about the scenario where you have a powered USB hub and you switch from powering it via a brick to powering it via your laptop... interesting, and actually very reasonable scenario. I guess given you have PD already built-in, it's not too hard to integrate that functionality either.

pestatije 4y ago

Wouldn't a powered USB hub do this?

OJFord 4y ago

Someone else brought that up, I don't really know, but my phone says it's 'charging rapidly' if I plug it into my laptop, so I just assumed it'd be possible.

derkades 4y ago

Newer phones and laptops can do PD both ways. It's a weird feeling at first to charge a laptop from a mobile phone, but it works!

sowbug 4y ago

You might be misunderstanding the idea. "used PD to power the disk" means the adapter used PD to obtain electricity, and then used that electricity to power the disk drive via the drive's normal power terminal. The disk drive still wouldn't know anything about USB Power Delivery.