We are currently verifying that our design meets the power up sequence per the reference manual. We are bypassing the internal DC/DC and all power rails come up in the correct sequence. However, we have an intermittent issue that occurs sometimes during a brief power cycle. The root cause appears to be the RT1176 "PMIC_ON_REQ" going low, about 5 mS after "VDD_SNVS_IN" goes high.
I can't seem to find anywhere in the reference manual that explains the cases when "PMIC_ON_REQ" would go low. There is one mention of when the "DCDC_IN" goes below 2.6V that will cause “PMIC_ON_REQ to go low. However, "PMIC_ON_REQ" still goes low and stays low even though “VDD_SNVS_IN” and “DCDC_IN” have remained stable throughout powerup.
