I am using EM2130L929QI to provide 0.9V core voltage for Cyclone 10GX FPGA. The device is turning off after between 2 and 45 seconds. I have another 2130 on the board providing 3.3V and it is working ok. The only difference between the 2 being the voltage output resistors.
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 ben supply and 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 ,
Since the part able to boot for some short time, that's mean there is a fault triggered.
So could you please share your schematic for EM2130_0.9V rail and also please provide a waveform for Vout during the fault.
Also the rail could shutdown if you are using a sequencer to control the on/off sequence and that controller bring the rail off.
So please also probe CTRL signal too incase that signal pull down after the power on.
Probably you are not able to communicate with the regulator through PMBUS if the bus is busy or the 5VCC is off.
I think I have found my problems. Firstly the RTUNE resistor was changed to 1K5 from 6K04 and the output of the regulator is stable for much longer.
I have 2 devices side by side (one for 0V9 and another for 3V3) and if I disable the 3V3 regulator the 0V9 device works perfectly and is stable and continuous. Long story short it looks like the 3V3 regulator is causing ground instability issues on the 0V9 reg. and I think the 0V9 was shutting down because of this.
Unfortunately it means a re-spin.
Hello @Ad13 ,
I am sorry, but could you please help to share a waveform for the issue, maybe we could fix the issue without re-spin the board.
Please help to share 0.9V and 3.3V regulators schematics for review.