@CentyLab well done! This project looks great and is certainly something that is of interest to a lot of people. I have been dreaming of/working towards the same goal of a compact usb-c powered variable power supply since the 240W announcement was made. My approach eventually deviated from PPS all together for one simple reason. Many usb-c power supplies do not implement it and I wanted a solution that could be helpful to as many people as possible. USB standards are complicated enough and it seems counterintuitive to select your phone charger or power bank based on the trigger you will use it with. Especially since most people who want to use a trigger board already own their usb-c supplies. I eventually settled on a buck converter approach in order to make a single design more compatible with more power supplies. I am currently preparing the design of the buck converter stage for a world with 48V supplies while I wait for more capable usb-c sink controller ICs to finally hit the market. In case you're interested: https://oshwlab.com/tuege/main-pcb (not complete quite yet). I can see however how people with PPS supplies would tend towards a simpler trigger design such as this one so once again, well done and thanks for sharing your design!

Hi Tuege,

Thank you for your comment. PPS is not as hard to find as you might think as Anker and Ugreen are supporting it for most of their charger now. Your method would be a universal approach for all USB PD, also at a higher amperage. I am very interested in your implementation of voltage and current control.

My original goal is to have a whole prototype lab that can fit inside your backpack.  You have a USB-C soldering iron, hot plate, and now power supply. One other reason that I am going in this direction is the existence of some Chinese modules that have built-in voltage control, current control, and also a big screen. Analog is not my strong suit and it is hard to compete with those Chinese modules.

Awesome project! It's perfect for something I'm working on, but was wondering if you have published the Kicad symbol and footprint anywhere?

I imagine I could mostly get away with using a generic Pi Pico footprint, but if there's significant changes anywhere it would be good to design my board with those in mind. Thanks!

Hi Patrick. It will work as it was designed with nearly exact dimensions and hole spacing as the Pico. It just doesn't have the castellated hole due to a major increase in cost. May I also ask what would be your application for this board?

Thanks for the response! My project is a USB C cable/power supply tester, that I'm hoping to use both for testing USB PD support (hence the use of your board), and also testing which USB C pins are populated in the cables (using two other USB C ports). I'm designing the board so it can also potentially be usable as a USB C power supply in the future as well.

I was also wondering, do you have any of the version 1.1 boards left? I'm worried that all my indicator LEDs (the design currently has 24 of them) may approach the 200mA limit of the voltage regulator in the version 1.2 design. 

Hi Patrick,

Unfortunately, we don't have any packaged V1.1. Would it be possible to limit the current to your LED, maybe running them at 5mA each?

Yeah, I can do that, I was just worried that might harm their visibility and/or make it more limiting for future uses of the board. I was thinking I might add a jumper to allow using VBUS instead of the regulated 3.3V for other components in case that becomes necessary. For my current project that'll be 5 volts, and not harmful to any other components, though of course that means I can't request higher PD voltages as needed. 

First at all, great project.

I've got some use cases i would use this hardware. What kind of PD source did you use for the serial example? I didnt get it working with serial AND power at the same time. With external powersupply i cant connect to PC (connector is pluged in the Power supply).

With connection to PC i didnt find a PD source wich would output power AND establish the serial connection.

Did you use different pins for serial?

Hi ManiSW,

Please check this one out: https://hackaday.io/project/192576/log/226908-enable-serial-debugging-on-picopd

Aah, i see. Second or splitter cable 👍 Thanks for the explanation.

This is some impressive work. In the meantime the S variant of AP33772S has been released. Looking at the datasheet they are pin compatible. Can you see any major hurdles apart from updating the library to support the AVS functionality?

Hi Guus, we didn't even know the AP33772S existed. Thank you for letting us know. The structure of the register should be similar but we first need to get our hand on one of the chips to test it out.

Hi Guus. Seem like the IC is only available in large reels in Summer. Lead time is a bit crazy. We will keep an eye on it.

Great! It's not so strange since PD3.1 power supplies are only just coming out. Looking forward to hearing from you again.

There seems to be an evaluation board out for this IC now. Should be in stock at Digikey in a little while: https://www.diodes.com/assets/Evaluation-Boards/AP33772S-Sink-Controller-EVB-User-Guide.pdf

Hi Guus, 

We might not wait for the AP33772S version as it is still very hard to get with long lead time. We are working on getting the code running for another IC to support 28V.

Hi AP33772S is now available at Mouser. If it helps I can pledge for 10 prototypes of picoPD with this version on board.

Hi Guus, we are currently working on the PicoPD Pro that ultilize this IC. We are expecting to launch this in 2 months after the code and higher voltage hardware has been tested.

Hi Guus,

We are working on the PicoPD Pro. We are finding differences to the order version that we will have to accommodated for. We are at evaluation board + code development stage.

Alright, we got a circuit working up to 28V. Testing up to 48V is hard as there are no such charger available. Due to the circuit required to operate at 48V, we cant fit it in Pico form factor, and must be a breakout board. However, support only up to 28V doesn't require much additional component.

This would be very interesting for industrial applications which run on 24V. Would be amazing to get 24V directly out of a USB-C supply. Let me know when you have this ready to go an I'll purchase a bunch right away.

Getting 24V directly out is possible. https://www.ti.com/lit/ml/slyp853/slyp853.pdf?ts=1725027002514&ref_url=https%253A%252F%252Fwww.google.com%252F

In the AVS, we should be able to request from 15V to 28V with 100mV step without current limit. Please let me know which form factor are you thinking of. With RP2040 microcontroller, or just a breakout board?

Hi. Having the rp2040 onboard would allow me to add a small screen and some buttons quickly. So that would be ideal.

Hi Guus, I just want to let you know the PicoPD Pro is released. More hardware documentation will be provided in the next couple of days.

Great! On my way to order some

Thanks for doing all this! Made implementing PD into my own project infinitely easier than I expected when setting out <3

This is a really cool project, and pretty close to what i want.  Two questions:

1) How hard would it be to use a potentiometer to change the request voltage?
2) can this handle a full 3 amps at the voltages?

1) Wiring is as easy as using a ADC Pin on the PicoPD and then changing the programming to scale the potentiometer to the pps range (0-20V) you could use two pots and do both voltage and current. i am working on this now but am waiting on a small 1.3" screen to show values as i need a small variable supply for field tests and i may use an encoder instead of a pot.

2) Being Fully PD3.0 Compliant the PicoPD can run upto  20V/5A (100W)

I will post my project once it is complete.

Hi Corhen. Please check out this example project https://hackaday.io/page/21022-variable-power-supply-with-usb-c-pps-picopd

I'd love to see this in format as those small PD decoy modules you can buy!
I wonder in theory how small this could get if was pre-programmed for a fixed voltage.

That is a good challenge. I might have to make them one sided to save cost. Are you thinking of decoy with PPS? Small but programable?

For non PPS, Adafruit just release a board that you can set voltage with solder bridge. But pps allow you to pull 5A at "any voltage"

Yes, PPS would be sick in that format, even if it's a set voltage. This would change everything when it comes to wall chargers and old/new electronics! 

Honestly, I would love to see something similar to the fpx PD trigger board, but with PPS (and EPR/AVS would be awesome, so maybe based on AP33772S)

Hi Jacobsson,

FYI, I am making a small trigger board that do exactly what you said. Aim to release in 3 weeks. I will create a project page soon

Please notify me when it's due! I love this ❤️

@jacobsson I just created a new project. I am a bit busy with work but the prototype is working. Please find the project here https://hackaday.io/project/193933-ppstrigger-board

Sounds good! Thank you

Is there a possibility of supporting PD3.1 in a future revision?

We do have PD3.1 (up to 48V) development in the pipe line. The silicon is a bit more difficult to source so we might have to gauge demand, and might even do a group buy.

i came across this chip it supports 3.1 and does not need alot of external components. i might do some design work if i get the time. HUSB238A

https://www.hynetek.com/uploadfiles/site/219/news/24322c00-2276-4d74-98db-c74432318210.pdf

@Nick Cook Hi, you have stumbled on the same IC as us. Same problem, we all need free time from daily job :(

@CentyLab I am not sure whether the HUSB238A would really work for pd3.1 up to 48V. The issue that I keep finding with ICs is that while in theory they support pd3.1, they connect to VBUS to verify that the voltage is correct and these sense pins tend to have too low absolute maximum voltage ratings in order to use them for a proper 48V setup.

@Tuege Neumann, Oh you are right. HUSB238A only supports up to 28V. Also just no higher than a 28V charger yet.

@CentyLab Good news though! I just investigated how the Framework 16 can offer charging up to 180W (with 240W charging being announced) and found out that they are using the CCG8DF IC by Infineon. Now this IC is theoretically also only rated up to 28V but one single line in the datasheet alludes to the fact that it can be used for higher power applications: "Note: Contact the Infineon local support team for application diagrams for any EPR designs with >= 28 V support." This is an option because this IC does not use a sense pin as previously mentioned and it does not need to be powered by the built in converter that is connected to VBUS. Instead it can be power through the VSYS power rail at 2.8 V to 5.5V which means that as long as there is an external converter that can handle the entire power range and provide either a 3.3V or 5V power rail (depending on your preference), the sink controller doesn't need to interfere with VBUS at all except through a load switch and therefore doesn't need to be rated for these higher voltages.

EDIT: Nevermind, unfortunately I just found out that the IC is only available on demand and is not stocked anywhere.

If you want to go the firmware way, there is a possible method right now. You can use a micro-controller that has built-in USB-PD CC PHY like CH32X035, then you can request anything without sensing the VBUS. If you want to check, you can always add a voltage divider or through another power control IC (current sensor ....)