Hi,
We are working on PCBA bring up. Two of the prototypes were damaged after a few power cycles. They have the same problem -- PMIC damage (PCA9450BHNY).
1. I measured the "resistances to GND" for each power rail, and noticed the VDD_SOC to GND was only 2ohm (damaged board).
2. For good boards, the VDD_SOC to GND were 50ohm ~ 70ohm. However, values for other power rails were around 1Kohm.
3. VDD_SOC to GND resistance on bare board was normal.
If the 50~70 ohm value is not correct, what could be the possible reason?
We are using "nano" processor, but still connected the K12, K13, L11, L13, M13, M14, N11 to VDD_SOC (like reference design).
Design guide recommended to tie MIPI-CSI to GND if unused. Should I connect them direct to GND or through a resistor?
Thanks.
We made 5 sample boards. 2 of them have PMIC damaged. However, VDD_SOC to GND resistance values are in the same range for good boards. I removed the damaged PMIC, measured again and still get similar value.