Hi, I have been trying to design a custom power supply for USB PD Rev3 using the STUSB4761 negotiator IC that can potentially support the Pi 5 at 5V 5A. The goal is to integrate this into a compact battery-powered robotics application.
I was testing this out on a Pi 4, and I think I may have accidentally fried it. Or a part of it, at least. Please help me debug. I will provide any other information you ask for.
Here is the behavior of the Pi currently. When I plug in the official 15.3W adapter, the red LED (power) lights up and the green one (status/ACT) doesn't light up at all. The main Broadcom CPU chip begins to heat up, but isn't at burning levels. I cannot test with a monitor or such, because I do not have one and cannot get one, I always use a headless SSH setup.
Here's whatever I know and what all I've tried. Since I initially used a custom supply, and then tried to debug using the official supply, I will indicate with each bullet point which supply was used for that symptom.
I was testing this out on a Pi 4, and I think I may have accidentally fried it. Or a part of it, at least. Please help me debug. I will provide any other information you ask for.
Here is the behavior of the Pi currently. When I plug in the official 15.3W adapter, the red LED (power) lights up and the green one (status/ACT) doesn't light up at all. The main Broadcom CPU chip begins to heat up, but isn't at burning levels. I cannot test with a monitor or such, because I do not have one and cannot get one, I always use a headless SSH setup.
Here's whatever I know and what all I've tried. Since I initially used a custom supply, and then tried to debug using the official supply, I will indicate with each bullet point which supply was used for that symptom.
- [CUSTOM SUPPLY] I know for a fact that my main power supply never exceeded 5V05, I was monitoring this.
- [CUSTOM SUPPLY] during my initial test with my custom supply, the Pi power-cycled rapidly for a couple of seconds until I killed power manually. The problems started after this.
- [BOTH CASES] no external peripherals are connected to the Pi
- [OFFICIAL SUPPLY] I tested all the test points 1, 2, 3, 11, 13, 14, 15, and 34 with a multi-meter. They all seem to be at expected voltages. But idk about TP15 VDD\_CORE, and it reads about about 1V. Source schematic: https://datasheets.raspberrypi.com/rpi4 ... matics.pdf
- [OFFICIAL SUPPLY] the 5V and 3V3 GPIO power rails are at the correct voltage.
- [OFFICIAL SUPPLY] I have tried with and without an SD card (also, the same SD card is able to successfully boot a different Pi).
Statistics: Posted by eccentricOrange — Mon Jul 21, 2025 6:12 pm