PD Power supply on Rock 4B+

The website https://wiki.radxa.com/Rockpi4/hardware/powersupply provides some information about power supply compatibility on Rock 4.

So we bought the PD power supply PD451A USB-C PD 45W that supports these outputs: 5V/3A, 9V/3A, 12V/3A, 15V/3A, 20V/2.25A. Used USB-C cable is LogLink CUA0106 (USB-C 3.2 up to 100 W, 480 MBps data transfer).

The problem is when using this power supply our Rock 4B+ randomly reboots several times a day. We have several pieces of this power supply and it behaves the same for all of them. System is idle, CPU temp is below 40°C.

But when we connect the standard Raspberry Pi USB-C power supply (5V/3A) our Rock 4B+ runs without any reboot for the whole weekend, even under heavy load.

What can be the problem? Is there some important factor that we must take in account when selecting the correct power supply? Or is just Rock 4B+ unreliable board?

If rock 4B+ works well with Rpi USB-C supply(5V/3A),the hardware should be ok, I think
It’s most likely caused by the power supply. you can try another PD power supply

Yes, I understand. The problem is that it appears for two different pieces of the same power supply. So my question is if I should look for some specific parameter when selecting the correct power supply. We cannot buy 10 different brands to see if some of them works. And PD451A USB-C PD 45W(/65W) is the only PD-PSU provided by our local stock that provides Radxa boards.

We could also stay with RPi PSU but since we plan to use NVME disk we are not sure if 5V/3A will be enough (+ 4x USB cameras + DSI LCD).

5V / 3A is not enough for full load, can you try another model USB-C cable?

So I tried some random phone PD charger with the same USB-C cable and exactly the same specification (5V/3A, 9V/3A, 12V/3A, 15V/3A) and it ran over the night without any reboot. So the problem may be the PD451A itself. But how to find what’s wrong? Is it possible that it loses power for a second when different voltage is requested? Is it possible to check it somehow manually (e.g. some user command that requests different voltage)? Or the specific voltage is requested only once during the boot?

I think the power is not enough at the negotiate voltage when the load increase at some point. there is no more methods to check, you can monitor the voltage and current all the process using the PD451A to find the current’s change before the system reboot

Ok. What I don’t understand is that it happens even under zero load - just cleanly booted up system waiting at login prompt.

We bought Raspberry Pi 5 official power supply 27W (3A @ 9V, 2,25A @ 12V a 1,8A @ 15V) and it seems to work too. However, there is some weird problem when trying to debug over serial console. When UART2_TXD/UART2_RXD are connected the board does not start at all with any of these PD PSUs (PD451A, RPi 27W) but it starts correctly with standard RPi 5V/3A PSU. I will continue in the separate topic about the serial console problems.