Want to make a 5V 5A USB-C PD power supply

[Alex_Baker]

Hello

For a project I am working on I want to power a raspberry pi 5 with a 4-cell lipo battery, since it is going on a drone. This problem has probably been solved before, but the issue with the Rpi 5 is that it wants to "handshake" over usb c with its power supply to see if it can get 5V at up to 5A, if it cannot it will complain and limit peripheral power, regardless of what power supply you have connected to the usb C port.

My goal is to find/build a real hardware solution to this(I know you can bypass the power supply detection in software, its not ideal). I started looking at a few USB C PD controller chips, but I quickly realized that I don't exactly know what I am looking at. Most of these chips are quite complicated, and all I want is a chip that can tell the Rpi that 5V 5A is available.

What would be the best starting point? are there cheap off-the-shelf solutions already that I can't find? There are tons of little USB C PD sink modules, but not any buck converters with a source controller built in.

TLDR: I want to build a buck converter with a USB C source controller in it. I can figure out the buck converter, I just need help with the USB C part.

[wasedadoc]

You CAN use a non-PD USB which delivers 5v 5A if you add a config line which tells the Pi5 that the PSU is indeed capable of that.

https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#differences-on-raspberry-pi-5

[Phil1977]

There are lots of PD-charger modules like the following available:

https://de.aliexpress.com/item/1005006482642562.html

The cheap ones are specified for 65W but usually overheat over 30W continuously. The problem for the Raspi may be that the cheap and small modules usually do not provide more than 3A of current, so the 5V/5A mode can not be chosen. As far as I know you need to use the heavier and more expensive 100W-modules if you want to get 5A current capability.

[Alex_Baker]

The cheap ones are specified for 65W but usually overheat over 30W continuously. The problem for the Raspi may be that the cheap and small modules usually do not provide more than 3A of current, so the 5V/5A mode can not be chosen. As far as I know you need to use the heavier and more expensive 100W-modules if you want to get 5A current capability.

Yes, this is the problem that I am noticing. The raspberry pi only needs up to 25W, but it only accepts 5V, thus needs 5 amps. It seems to be difficult to find anything that will do 5 amps. Even the power delivery controller chips have the current set at 3 amps default for the 5V PDO, so I would need to change the firmware default to 5 amps.

[Smokey]

There is a configuration option to have it stop complaining if it's not connected to a USB PD device.  This is what you need to do if you are powering the thing from the pin headers.  No PD supply needed.

gg.  wasedadoc beat me to it

[Phil1977]

If you need it to be USB PD powered you can try this device:

https://de.aliexpress.com/item/1005005281312049.html

Of course I can't guarantee because I don't know about different versions of this module. But the one I have delivers 5V 5A - only if you connect a cable with an e-marker chip for 100W operation.

[fchk]

For a project I am working on I want to power a raspberry pi 5 with a 4-cell lipo battery, since it is going on a drone. This problem has probably been solved before, but the issue with the Rpi 5 is that it wants to "handshake" over usb c with its power supply to see if it can get 5V at up to 5A, if it cannot it will complain and limit peripheral power, regardless of what power supply you have connected to the usb C port.

Your problem is that 5V 5A is non-standard.

According to the USB PD Spec R3.2 V1.0 Section 2.8 "Charging Models" you can only request 5A with 20V. For all other standard fixed voltages (5V, 9V, 15V - 12V is also non-standard) you can only request 3A.

A charger with Programmagle Power Suply (PPS) Charging mode may support 5A with 20V baseline voltage and a programmable output volt range of 5V to 21V, if using an electronically marked 5A cable. I guess this is what the Raspberry foundation is using.

You see Power Delivery is messy - 1113 pages long.

You are better off looking here and use this setting:
https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#PSU_MAX_CURRENT

[Phil1977]

It seems to be non-standard but not completely uncommon.

Most 100W-sources I had tested so far offer the 5A at lower voltages too.