3 ms·
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
by 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 agoNo, 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 agoWhat 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 agoYou 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 agoUnderstood 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.