I have a framework Laptop 13, with the official 60W charger, I’ve been using it to test USB-PD trigger boards, and realized that it refuses to output 12V. When I try to select 12V, it outputs 9V, but I can select the 15V and 20V settings, which work fine. When testing the same USB-PD trigger board on a variety of other chargers, they’re all capable of outputting 12V. I wonder if this is just some technical limitation of the 60W charger, or if there’s something else going on here?
I will just use other chargers for my projects going forward, but I’d still like to know whether this is just a limitation of the charger, or something else is going on. I guess the Laptop never uses 12V for charging, but it still seems weird that only 12V is missing.
12V PDO was a profile along time ago, but that was basically thrown out of the PD standard before we even got USB-C. So its a legacy and deprecated profile that is completely optional and not recommended for USB-C chargers to support. Very few devices use it, as they cannot rely on any charger actually supporting it. Only 5V, 9V 15V and 20V are official PDOs of up to 100W PD chargers.
The FW 60W charger hence does not support a 12V profile and does so completely in accordance with the PD specifications.
But since the FW charger does support PPS, any device can just request an arbitrary voltage between 3.3V and 21V and the charger will supply it. I guess your trigger boards don’t support any of the advanced PD features, simply blindly request the legacy 12V profiles and fallback on requesting completely different voltages if that is not available. So this is much more about your trigger boards and how those don’t do anything safe (i.e. don’t connect power if its not what the user configured).
@Ray519 Thanks for the answer, I pulled another, larger/more expensive trigger board out, and it does manage to get 12V from the Framework charger, which aligns with what you’ve said. Seems like the smaller, cheaper trigger boards are gonna be a bit more hit-and-miss with what chargers they can get 12V from.
Thanks again for the quick response, it’s exactly what I wanted to know.
Framework should list all voltage/current specification on the product description page, not just “generic”
An ultra-high-efficiency 60W charger using GaN technology to stay cool and compact. The included detachable USB-C and AC cables make it easy to adapt to your needs.
It was not. But USB started designing the PD standard originally for USB-A.
That was PD version 1.x. It never made it into actual products before they had that change of heart, dropped all USB-A support, replaced with USB-C and replaced 12V with 15V. That is why 12V is so legacy. It was already removed before the first versions we ever saw in the wild (PD 2.0 and onwards).
Just that PD technically allows you to declare any voltage in those profiles, it just would be a non-standard one that likely no device other than your own would use.
Nintendo Switch 1 is like one of the examples of a device actually using 12V PD in some cases.
USB-PD without the extra USB-C-only CC pins would be something substantially different from USB-PD as we know it now. I didn’t realise it even existed.
Don’t know. But I imagine once you defined 20V, 5A and 3A as your limits, 15V probably allows for a more sane intermediate step (i.e. mandatory from 27W up to 45W, when 20V also become mandatory. For 12V you would reach the upper end at 36W with the same 3A limit, which hardly sounds worthwhile).
Edit: They also apparently had not defined 9V as an intermediate step, back when 12V was still it (so it was 5V, 12V, 20V and they changed it to 5V, 9V, 15V and 20V). Presumably on input from manufacturers.
And its close enough to 12V that it should be easy for hardware originally designed for 12V to be easily modified to make it work.
Also, there are very few things that run on those voltages directly. Its just a common intermediate level between external power supplies and internal power circuitry.
But if you consider you need to design all the port, electronics for USB-C and PD handling, stepping voltage down from a different voltage is like the simplest thing you need to do. So probably not much interest in using that. Especially vs. 19-20V on which almost any notebook run on, which were prime candidates since USB-C is already designed for PCs.
Thanks for your information. From I understanding the 12V, 24V etc is more from industries that many have currents of 10A, 20A, 30A etc, so they are not the same type of devices that common USB port powers. Thus, PD “split” the 12V into 9V and 15V to give more steps