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DLP9500: Zener Diode on VOFF&VCC2

Uryyy
Expert 1770 points
Part Number: DLP9500
Other Parts Discussed in Thread: DLPA200

Hello,

Each schematics assigns zenner diode as below. However, the comment says both assignment is not correct. Can we remove D8 on DLPA side or D1 on DMD side?

  • 0
    TI__Expert 3700 points

    Hi Uryyy,

    The schematics that you attached are for two different voltage supplies. VOFF_1 and VCC2.

    The zener on VCC2 should be followed for the DMD board design.

    For the VOFF_1 supply, the schematic has a comment that a zener should be used on either the DMD or the controller board, but is not need on both boards.

    Please let us know if this is clear and answers your question.

    Thank you,

    Matt

  • 0 in reply to Matt Soucek
    Expert 1770 points

    Hi Matt,

    VCC2 on DMD board looks it comes from VOFF_1 on DLPC&DLPA board.

    Reagrds,

    Uryyy

  • 0 in reply to Uryyy
    TI__Expert 3700 points

    Hi Uryyy,

    I will check on this again tomorrow when we are in the office. Thanks for your analysis.

    Regards,

    Matt

  • 0 in reply to Matt Soucek
    Expert 1770 points

    Hi Matt,

    Thank you for your quick answer.

    Also, I believe VOFF_1 = VCC2 by DLPA200 datasheet.

    Regards,

    Uryyy

  • 0 in reply to Uryyy
    TI__Expert 3700 points

    Hi Uryyy,

    Thank you for your analysis!

    Yes, it looks like one zener is needed. On the controller board, the VOFF_1 from the DLPA200 is connected to the DMDVCC2 pins on the flex cables to the DMD board. There is then a circuit on DMDVCC2 that shows VCC2.

    The first schematic copy you sent is the VCC2 node with the zener.

    I haven't found an EVM board here in the lab but am still looking. My goal is to just double check your analysis and my review today.

    Regards,

    Matt

  • 0 in reply to Matt Soucek
    TI__Mastermind 43165 points

    I believe on our EVM the Zener is not populated on the controller board, but on the DMD board.  It does NOT need to be on both.

  • +1 in reply to Fizix
    TI__Mastermind 43165 points

    Urrry,

    I must correct my last posting on this.  I went to the lab and inspected a controller board and the controller board DOES have D8 installed.  There is no Zener on the DMD boards.

    We do recommend for production systems that a Zener be installed that is closer to VCC2 (=V offset).

    Here is a picture of D8 on the Controller board:

    Sorry for any confusion on this.

    Fizix