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VCORE and VYS not coming up

Question asked by Ashwat Amirthalingam on May 29, 2019
Latest reply on Jun 12, 2019 by G.w. Sun



I have 2/30 boards with the PF1510 with the following symptom:



-> VCORE and VSYS do not come up.


I measure the following voltages on those boards:
VIN = 5V, LDO2P7 = 2.7V and VCOREDIG = 1.48V


According to the above startup sequence, VCOREDIG and VCORE should come up before VYS. However, the Internal Block Diagram indicates that the VCORE and VDIG are derived from LDOs supplied by VSYS. 


This implies that the VCORE and VDIG voltages should come up after VSYS. 


Please help me understand the following:

1. What does the startup sequence indicate?

2. Why is the VCORE not coming up on the two defective boards? What is this symptomatic of? There is no obvious short circuit on any of these rails.

3. VIN_VALID is a register. What is BGOK?



Thanks for you help,

Ashwat Amirthalingam