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TaeHoLee's avatar
TaeHoLee
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2 years ago

Cyclone V device difference between 5CEBA7F23C7 and 5CEFA7F23I7

I programmed using the Cyclone V device, 5CEBA7F23C7, and it operated normally. I changed the device to 5CEFA7F23I7, confirmed pin-to-pin compatibility, and didn't use HMC. Instead, I implemented the memory controller in software. There were no circuit changes.

I recompiled the program for 5CEFA7F23I7 after changing only the device, and the FPGA was programmed. When the FPGA was empty, the impedance measured around 90 ohms, but with the code, it dropped to 3 ohms.
Even after deleting the code and overlaying with an empty project, the impedance does not return.
The functionality is normal, but the lower impedance results in more heat compared to the commercial-grade device.

Is it normal for the impedance to measure low? Would raising the core impedance resolve the heating issue? Can the impedance be increased? Generally, does an industrial-grade device produce more heat than a commercial-grade one?
Fpga Devkit

7 Replies

  • TaeHoLee's avatar
    TaeHoLee
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    2 years ago
    The mentioned impedance is for the 3.3V. The main voltage for the core is 1.1V, and the 3.3V is supplied to the FPGA's 3.3V BANK for IO and oscillator initiation, only used for JTAG.

    Please help this novice. Thank you.
  • FvM's avatar
    FvM
    Icon for Super Contributor rankSuper Contributor
    2 years ago

    Hi,

    presume you measured "impedance" with a multimeter. The measurement doesn't mean much because I/V characteristic of supply rails is highly non-linear. Initial current at low voltage ("impedance") also depends on residual charge on internal nodes.

    The only reliable information for power consumption is actual supply current. You also need to assure that the design doesn't involve floating inputs without termination.

    Regards
    Frank

    • TaeHoLee's avatar
      TaeHoLee
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      2 years ago
      Impedance-related response is appreciated. However, I'm curious about your thoughts on the device generating heat while pulling a significant current yet still operating normally.
  • NurAiman_M_Intel's avatar
    NurAiman_M_Intel
    Icon for Super Contributor rankSuper Contributor
    2 years ago

    Hi,


    • What pin that you are measuring?
    • You said that you changed the device from 5CEBA7F23C7 to 5CEFA7F23I7, did you also change the board?
    • If you are using the same board, did you re-solder or solder the board/device when changing the device? It could be the board issue.

    Regards,

    AIman


    • TaeHoLee's avatar
      TaeHoLee
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      2 years ago
      Hello,

      The board used was originally designed for the 5CEBA7F23C7 chip, and then multiple boards were created by maintaining the same circuit and layout while replacing the chip with 5CEFA7F23I7.
      Is it correct to understand that, generally, when you change only the device on the same board, there are no issues with heat or current?

      Thank you.
  • NurAiman_M_Intel's avatar
    NurAiman_M_Intel
    Icon for Super Contributor rankSuper Contributor
    2 years ago

    Hi,


    To make my understanding clear, there is no solder or resolder occur on the same board? Meaning you did not resolder device 5CEBA7F23C7 then solder 5CEFA7F23I7 to replace the 1st device? You just created multiple boards by maintaining the same circuit and layout and directly replace with 5CEFA7F23I7?


    I saw my colleague are also supporting you with the same issue in https://community.intel.com/t5/Programmable-Devices/Cyclone-V-Pulling-excessive-current-at-3-3V/m-p/1561447 ? Is it Ok if i close this thread and you can continue to get support from my colleague in the other thread?


    Regards,

    Aiman