I have tried to connect to the device via the SPI bus but it does not appear to be communicating. I have isolated the regulator and used a 0.9V bench supply and the board is pulling about 250mA on the 0.9V rail which seems reasonable.
I'm at a bit of a loss and need to understand why the regulator will turn itself off.
Any help appreciated.
Hello @Ad13 ,
We are sorry for late response.
It looks from your description that this issue related to stability issue.
Could you please provide EM2130 schematic and Vout waveform during the startup issue.
Please probe Vout, PVIN, VDD33 and VCC pins and proved the startup waveform.
Also if the PMBUS lines is busy or VCC is off, you can't communicate with the part.