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DM3730 unused cvideo pins

Jerome Schmidt
Prodigy 25 points
Other Parts Discussed in Thread: DM3730

This is a portion of text that comes from a "caution" box in section 7.2.3 of the DM3730 technical reference manual:

 "If the TV output is not used, the following configurations for the AVDACs pins must be applied:

- Configuration 1

  • cvideo1_out must be grounded.
  • cvideo1_vfb must be grounded.
  • cvideo2_out must be grounded.
  • cvideo2_vfb must be grounded.
  • cvideo1_rset must be grounded.
  • vdda_dac must be grounded.
  • vssa_dac must be grounded.

- Configuration 2

  • cvideo1_out must be floating, left unconnected.
  • cvideo1_vfb must be floating, left unconnected.
  • cvideo2_out must be floating, left unconnected.
  • cvideo2_vfb must be floating, left unconnected.
  • cvideo1_rset must be floating, left unconnected.
  • vdda_dac must be grounded.
  • vssa_dac must be grounded."

 Besides this caution statement, where are configuration 1 and configuration 2 defined?  Does it matter which one we choose?

  • 0
    TI__Guru*** 125430 points

    There's no register to configure which way you hooked it up.  It's simply 2 different terminations for unused TV DAC.  I recommend using Configuration 1 which matches the recommendation from the Schematic Review Checklist.

  • 0 in reply to Brad Griffis
    Prodigy 25 points

    So...  it sounds like we can leave them unconnected or grounded, but the preferred method is to ground them.  On this design we are choosing to ground them as you indicated, but there have been other designs that left them unconnected.  Do these other designs face any risks (power, EMI, etc.) by having them unconnected?  Thanks.

  • 0 in reply to Jerome Schmidt
    TI__Genius 16690 points

    If they are unconnected, the power consumption could be slightly higher as indicated in schematic checklist. Please make sure that the register setting recommendation in the schematic checklist is implemented in both designs.

     

    When the TV output is not required then the following configuration should be implemented in order to reduce the power consumption to its minimum value.

    The analog pins tv_vref, vssa_dac, VDDA_DAC, tv_out1/2 and tv_vfb1/2 should be grounded. (Signal names appear as CVIDEO1_OUT, CVIDEO1_VFB, CVIDEO2_OUT, CVIDEO2_VFB, CVIDEO1_RSET in TRM SPRUGN4M)

    To avoid internal current leakage, the following bits must be set to 0: DSS.DSS_CONTROL[5] DAC_POWERDN_BGZ DSS.VENC_OUTPUT_CONTROL[2:0] PRCM.CM_FCLKEN_DSS[2] EN_TV CONTROL.CONTROL_DEVCONF[18] TVOUTBYPASS