• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 2 answers
  • Subscribers 14 subscribers
  • Views 1066 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

THS8200-EP: Schematic design review

Lilian Chang
Intellectual 1555 points
Part Number: THS8200-EP
Other Parts Discussed in Thread: THS8200

Hi Team,

My customer will use THS8200 on board to convert BT.1120 to VGA. Could you please kindly help to review schematic design as attached?  Thank you.   

 Input signal : YCrCb 4:2:2 /16bit

Internal sync

  • 0
    TI__Guru 62930 points
    Lillian,
    I will review this and get back to you soon.
    Regards,
    Wade
  • 0 in reply to Wade Vonbergen
    TI__Guru 62930 points

    Lillian,

    Here are comments on schematic.

    Suggested to use pulldown resistors to bias unused data inputs to ground (RCR and unused bits of GY, BCB)

    Recommend reviewing layout document here:

    If using split plane, then AGND/GND_DLL should be filtered from DGND.

    It was also suggested that AC coupling to be used on outputs.  This is application specific.

    Passive reconstruction filters are okay, but better quality can be achieved (with higher cost) when using an active filter.

    May want to consider using level shifters on the H & V syncs, as these should technically be 5V outputs.  However most modern monitor work well with 3.3V outputs.

    BTW, the EP version of this device is moving to NRND status soon.  This is due to the lack of expertise remaining for this device within TI.

    Regards,

    Wade

  • 0 in reply to Wade Vonbergen
    TI__Intellectual 1555 points

    Hi Wade,

    Many thanks for your support!

    two questions:

    1.   May want to consider using level shifters on the H & V syncs, as these should technically be 5V outputs.  However most modern monitor work well with 3.3V outputs   -> You mean from our device, HS/VS_OUT signal level  is 5V?  

    2.   It was also suggested that AC coupling to be used on outputs.  -> Suggest add AC caps on RGB output, right?  What's the recommend AC cap value?

  • 0 in reply to Lilian Chang
    TI__Guru 62930 points
    Lilian,
    For number 1, yes that is correct. The THS8200 is a 3.3V device, and can only output 3.3V. The specification for on these signals calls for 5V. As mentioned, most hardware works well with 3.3V.

    I am trying to get clarification on number 2. I hope to be able to update this today.
    Regards,
    Wade
  • 0 in reply to Wade Vonbergen
    TI__Guru 62930 points
    Lilian,
    Apologize for the delay.
    With respect to the use of the AC coupling caps.
    The suggestion to use the AC caps was based on compatibility with older displays. Virtually all modern monitors have ac coupling and rebiasing built into the monitor. This for newer monitors, this ac coupling at the driver is not necessary.
    If customer will need to drive monitors that do not rebias to appropriate levels, then they would want to consider AC coupling.
    If they were to AC couple, common AC caps would be in the 330 to 470uF range.

    Regards,
    Wade