Dear support team,
I am using EM2130L/H to generate 0.9 V and 3.3 V for a Cyclone 10 GX FPGA. And I am having some issues.
I have tested two boards. On the first board, EM2130L outputs 0 V, and its 3.3V output of the internal LDO (Pin 16) is 0 V. EM2130H outputs 0.78 V, and its 3.3V output of the internal LDO is 4.3 V.
On the second board, the output 0.9 V of EM2130L is good, but the 3.3 V output of EM2130H is about 2.04 V. The 3.3V output of the internal LDO (Pin 16) is OK.
I copied the design of the Cyclone 10 GX Development Kit Board (Schematic available at https://www.intel.com/content/dam/altera-www/global/en_US/support/boards-kits/cyclone10/c10gx-dev-ki...). I attached the schematic of my design (only EM2130 part).
The CTRL pin of both EM2130L/H is connected to the output of a power sequencing chip (LM3881) and is verified to be high (2.76 V). For EM2130L RTUNE resistor (R55), I do not have a 6.04 kohm resistor, so I use a 6.20 kohm instead. For EM2130H, for the first board, RTUNE is 0.390 kohm, while on the second board, I try 0.390 khm and 0 kohm, but the output is the same (2.04 V).
I have a few questions.
Hello Andy Liu,
I am sorry for late response.
Since 0.9V design works in one of your board, probably there is no design issue.
It looks the issue maybe be a soldering issue since one of the board shows VDD33 voltage is 4.3V.
Also to confirm if we don't have stability issue, please disable the remote sensing by unmount R60 and R62 and change Rtune to 0R (the loop is not optimized)
Please probe Vout, PVIN, VCC, and CTRL signals of regulator and share the scope waveforms.
If you have the capability to communicate with the regulator using the GUI through the PMBUS, so we can check if there is any fault that triggered during the startup.