Septimaeus@infosec.pub 4 days ago
Isn’t that nonconformant?
Not to my knowledge. It has always been optional.
Why? PPS offers the most granular realtime PD adjustments of not only voltage (in tiny 20mV steps) but also of current delivery (at I think 50mA increments but don’t quote me). This is why it’s typically required by manufacturers for their fastest device charging speeds. PPS allows the most precise matching of power delivery to what BMS reports cells can absorb with little to no onboard power conditioning and minimal waste heat. It’s a premium rating beyond standard compliance.
A potentially interesting follow-up question, however, would be whether the laptop’s mainboard PDO tells you the laptop supports PPS, even though the power brick doesn’t.
daveyOsborn@infosec.pub 4 days ago
I appreciate the link. I wanted to see what you saw, so I opened the ZIP file and it expands to 27 files. I believe the relevant file is
USB_PD_R3.2_V1.2_2026_05_20.pdf, page 42, which states:If it’s optional in rev. 3.2, I assume it’s optional in rev 3.0. I’m a bit astonished because PPS is probably the most signficant feature of rev.3. The industry is not competent enough to even tell consumers which rev a device conforms to. But if it did, typical Wikipedia-informed consumers who see PD “rev.3” advertised would naturally expect PPS. As you are correct that PPS is indeed optional, many consumers will get burnt by the misunderstanding.
What’s PDO?
The problem seems to be that a laptop could be designed to /need/ PPS, e.g. if the voltage it needs is well below 20v. While most PSUs do not advertise USB-PD 3(+) compliance, much less PPS.
Septimaeus@infosec.pub 3 days ago
Power Data Objects are sent by the device to the host (in this case your power supply) containing information about device capabilities and requirements.
This would be highly unusual, especially for a Dell workstation laptop. Some laptops can use PPS for better internal power efficiency and battery charging rate, but I know of none that require it. The feature is also leveraged far more often in small sealed devices where waste heat has basically nowhere to go, so if any device were to actually require it, I would look to small wearables. In fact, while I haven’t checked and don’t know, I’d wager many smart watch chargers are PPS enabled, which would explain their oversized connectors.