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navgh77's avatar
navgh77
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1 month ago

Stratix 10 FPGA Dev Kit VCCIO_FMC voltage issue

The FMC VCC IO voltage level is adjustable using a resistor on the board as shown below. The default is 1.8V and that works fine. When I depopulate the resistor (R468) to get 1.2V, the output voltage goes to 0V and the enable line for the DC-DC converter also goes low. Any idea what the reason for this is? And what is the fix?

 

 

 

Board Debug
Fpga Devkit

10 Replies

  • AqidAyman_Altera's avatar
    AqidAyman_Altera
    Icon for Regular Contributor rankRegular Contributor
    1 month ago

    Hi,

     

    Thank you for reaching out to us. I will help you with this.

    Can you confirm what the devkit OPN is for this case?

    • AqidAyman_Altera's avatar
      AqidAyman_Altera
      Icon for Regular Contributor rankRegular Contributor
      1 month ago

      As per my understanding, even the devkit supports adjustable voltage at VCCIO_FMCA, if you only depopulate R468 to “get 1.2 V,” the regulator’s selection network is left in an invalid state. The kit’s power sequencing/monitor circuitry then detects an under‑voltage/fault and pulls the converter enable (EN) low, so the rail collapses to 0 V. Can you try to follow the resistor settings in the user guide, which leave all of the resistors open to get 1.2V.

      Refer here:

      https://docs.altera.com/r/docs/683674/current/stratix-10-gx-fpga-development-kit-user-guide/default-switch-and-jumper-settings 

      • AqidAyman_Altera's avatar
        AqidAyman_Altera
        Icon for Regular Contributor rankRegular Contributor
        1 month ago

        Are you removing all the mentioned resistors, which are R460, R464 and R468? Based on my understanding, you depopulate R468 only.

        Correct me if I'm wrong.

         

        If you already done that, I suggest you below steps:

        1. Ensure R468 is removed and that R460 and R464 are not populated (verify no solder bridges). That yields 1.2 V per the user guide.
        2. Bring-up check
          • Power cycle the kit after changes.
          • Verify VADJ at the FMC test point and confirm the Power Good signal remains asserted.
          • Test without an FMC card first; then use only FMC cards that support 1.2 V VADJ.
  • navgh77's avatar
    navgh77
    Icon for New Contributor rankNew Contributor
    1 month ago

    What do you mean by "follow the resistor settings"? The user guide mentions not installing the 3 resistors should get you 1.2V output. Is there another resistor setting guide I should be following?