Ok, many comments here but so far I haven't got much further in my understanding of the problem.
@Jamesh, thank you for your comment but if it is just the I2C communication with the PMIC that fails I do not understand why the CPU gets very hot. Could you, or your colleagues, provide me with a replacement PMIC (I believe this is a non-standard part)? If so, I can replace and see whether it indeed is (just) this chip that is failing. Could be worth a try.
I am open to the fact that it could be my power supply that is failing and generating an abnormally high voltage in some situation. But it is not very likely. And I have shown that it sits nicely at 5.1V when loaded.
I have also shown that it goes a little further up, towards 5.7V, for a few ms, when cold-started by connecting to mains, but I very much doubt that this is destroying the RPi's. If it is then I think it would be a severe design issue with the RPi itself. And it has been mentioned here that there haven't been many reports about destroyed RPi 5's which speaks against it being so extremely sensitive on the supply line. (Just imagine what a little ESD could raise the voltage to, even on a low impedance supply node!)
Furthermore, more than one commentator has advised me not to use anything but the official RPi power supply. In response to this I would like to say that being limited to using only the official power supply makes the RPi much less attractive as a computer board for embedded applications. In many cases one wants to use a 5V power rail generated from a common supply for other equipment or even generated from a battery and a buck/boost regulator. In addition, the use of a USB connector for supply makes it easy to use whatever supply is available and if this was not the intention I think there should instead be a non-standard connector.
By the way, I cannot even find a spec of what voltages the RPi 5 should be supplied with. Just the commonly mentioned very imprecise value 5V.
And the official power supply, which is marketed as "an ideal power supply for Raspberry Pi 5" (and not as something that is mandatory to use) is rated just "Output voltage: 5.1V" without any min, max, or other details.
@Jamesh, thank you for your comment but if it is just the I2C communication with the PMIC that fails I do not understand why the CPU gets very hot. Could you, or your colleagues, provide me with a replacement PMIC (I believe this is a non-standard part)? If so, I can replace and see whether it indeed is (just) this chip that is failing. Could be worth a try.
I am open to the fact that it could be my power supply that is failing and generating an abnormally high voltage in some situation. But it is not very likely. And I have shown that it sits nicely at 5.1V when loaded.
I have also shown that it goes a little further up, towards 5.7V, for a few ms, when cold-started by connecting to mains, but I very much doubt that this is destroying the RPi's. If it is then I think it would be a severe design issue with the RPi itself. And it has been mentioned here that there haven't been many reports about destroyed RPi 5's which speaks against it being so extremely sensitive on the supply line. (Just imagine what a little ESD could raise the voltage to, even on a low impedance supply node!)
Furthermore, more than one commentator has advised me not to use anything but the official RPi power supply. In response to this I would like to say that being limited to using only the official power supply makes the RPi much less attractive as a computer board for embedded applications. In many cases one wants to use a 5V power rail generated from a common supply for other equipment or even generated from a battery and a buck/boost regulator. In addition, the use of a USB connector for supply makes it easy to use whatever supply is available and if this was not the intention I think there should instead be a non-standard connector.
By the way, I cannot even find a spec of what voltages the RPi 5 should be supplied with. Just the commonly mentioned very imprecise value 5V.
And the official power supply, which is marketed as "an ideal power supply for Raspberry Pi 5" (and not as something that is mandatory to use) is rated just "Output voltage: 5.1V" without any min, max, or other details.
Statistics: Posted by sm6vfz — Mon Jul 29, 2024 3:52 pm