09-15-2020 06:16 AM
during a measurement with the ZCU111 evaluation board in the lab 2 of the power LEDs stopped glowing:
the VCCINT_IO_BRAM_PS_SDFEC and the and VADJ_FMC. I measured the voltages and got 0.001V and 0.1V, respectively.
During the measurement I had connected an external custom board to the LPAF connectors for the ADCs/DACs.
I am trying to locate the error and have considered the following options:
A short circuit on the external Board; ESD damage; a software/configuration problem; ...?
From what I saw in the ZCU111 schematic, these voltages are not available on the LPAF connectors, which makes me think that the external board could not be the cause? Furthermore, these voltages come from two different PMICs. All other voltages coming from these two PMICs are correct.
Unfortunately I cannot connect to the board anymore over Ethernet or via UART, switching power on/off does not help.
Any suggestions on how to debug/locate the error? Are these voltages dependent on each other?
09-28-2020 01:31 AM
Vadj should be 1.8V if no daughter card mounted on LPAF connector. So if you see 0V in this case, Vadj output should have something wrong with it.
As for VCCINT_IO_BRAM_PS_SDFEC , this power rail should be 0.85V at any time. Have you ever touch the power IC that output these two power rails? Is there any overheat?
10-08-2020 02:14 AM
Hello @zhendon , I haven't touched anything, and the U53 PMIC chip is actually on the bottom side of the board. The board was on an ESD mat during the measurements. I bought an Infineon USB005 cable to check if it is a programming fault in the PMICs and the U53 Chip (responsible for VCCINT_IO_BRAM_PS_SDFEC) is giving an overcurrent protection (OCP) error. I removed the inductor (L22) after the powerstage chip in order not to damage the FPGA and still the PMIC is giving an OCP error. Then we replaced the powerstage U54 (TDA21240) because it seemed to be the problem. With the new powerstage and L22 removed, the PMIC is still giving the same error. I resetted the error register of the chip but the OCP error appears again.
Based on my understanding, there should not be any current flowing when L22 is removed, which would mean that the PMIC is the problem? However I saw this post: https://forums.xilinx.com/t5/Xilinx-Evaluation-Boards/Power-supplies-of-ZCU111-malfunctioning/m-p/1150410/highlight/true#M29242 and it seems like swapping out the PMIC is also not necessarily going to help?
Can it be that the instability issue from https://www.xilinx.com/support/answers/71901.html caused a failure in this PMIC - Powerstage chain due to a higher current consumption?