Hello we've being using the E3827 on our own custom PCB for a while now and are nearly into production stage. We're seeing the following issue on about 10% of our prototype systems:
- The PMIC is providing all A Rails for G3 state. Regulation, noise and sequencing are all okay.
- The Intel’s PMC clock is running and PMC_SUSCLK[0] output is at 32.768KHz
- PMIC is waiting for SLP_S4_B to be asserted from the CPU however the CPU does not assert this line and the system is stuck and never goes into S4 state.
The only way we can fix this is to force low the PMC_PWRBTN (J26) signal on the Intel CPU for a second or so. This fix only needs to be done once, after this the intel will boot every time with no intervention.
There is no reference to the PMIC datasheet or the Intel datasheet to the PMC_PWRBTN signal during S4 transition.
Has anyone seen this problem before?
I could apply the above mentioned fix to the production FCT fixture but I would rather find the source of the problem.
Thanks is advance,
Erik