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F2808 Control Card Power issue.

Omer Peleg
Intellectual 640 points

Hi.  I've designed my own PCB that uses the F2808 Control Card.  I have a 2 internal power planes, GND, and 5V.  Each power pin from the DIMM connector goes straight to the power or GND plane.  When I apply 5V to the board, the controller works randomly.  I will either have problems when I power the board, or when I try to debug it with CS4.  However, if I lower my 5V supply to around 4V, I don't have any issues at all.  The only difference between my board and the evaluation boards is that I route the 5V pins directly to the power plane.

 

Any suggestions?

Thanks,

Omer Peleg

Data Technologies Inc.

  • 0
    Expert 2730 points

    Operating voltages for the F2808 are 3.3V for I/O supply and 1.8V for core supply and you will need both voltages. 5V is too much directly for the controller.

  • 0 in reply to JHi
    Intellectual 640 points

    I am using the F2808 Control Card.

  • 0 in reply to Omer Peleg
    Expert 2730 points

    I should have read your post more carefully. Here is a short check list:

    - Where do you power up your JTAG emulator and which emulator are you using?

    - Does the emulator require 5V or 3.3V?

    - Did you check for the short circuits between power pins ( #77, #02, #87, #92 and #96 in DIMM-100) and  normal I/O pins? Normal I/Os can't handle 5V.

    This 5V seems to be the problem if everything works when you lower your voltage to 4V. So you might have 5V where you should not have.

     

    JHi

     

  • 0 in reply to JHi
    Intellectual 640 points

    I am using the Blackhawk USB2000 emulator.  I believe it should handle 5V, but I had a difficult time verifying.   However I am still having issues without connecting the debugger.  I will check for shorts as you suggested, thanks.

    Omer

  • 0 in reply to Omer Peleg
    Intellectual 640 points

    Thanks for your help.  I seem to have found the problem.  I had an optoisolator for the spi interface (ADUM1401) that was powered to 5V.  Even though the SPI was disconnected I believe the floating signals caused 5V to go to the DSP.

     

    Thanks,

    Omer