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SN75DP130: Squelch release

F.N
Expert 8760 points
Part Number: SN75DP130

Hi team,

My customer evaluates SN75DP130 with the configration shown in the datasheet Figure 22
with Link Training enable in DP mode.

In customer's evaluation, output did not come out even if the amplitude recovered, after
the input amplitude of the device became 0 V and the output ceased to be output.

According to the datasheet Figure 18  Operating Modes Flow Diagram, when Squelch is released,
the mode transitions from output disable to active.

The customer want to know why the mode does not transition to Active. And the customer also
wants to know the presetting of the register which will make the mode transition to active
when amplitude recovers.

Please let me know.

Best regards,
Fumio Nakano

  • 0
    TI__Mastermind 19720 points
    The part might not be transitioning from output disable mode to active mode because the Squelch sensitivity is too high. The SQUELCH_SENSITIVITY register can be changed to the input level that you need to change the mode from output disable mode to active mode. the SQUELCH_ENABLE mode is the register to change to enable or disable squelch and is defaulted to enable the feature
  • 0 in reply to Michael.Walker
    TI__Expert 8760 points

    Hi Michael-San,

    Thank you for your prompt reply.

    Sorry for the unclear question. I will ask again.

    Customer evaluation register settings are below.

    ・DP mode

    ・Squelch is enable　(default).

    ・Squelch detection threshold is 80mV (default).

    VID is 600mV or 0V.

    Customer evaluation sequence and results are below.

    ①When VID is 600mV, SN75DP130 outputs video stream. (Active mode)

    ②When VID changes from 600 mV to 0 mV, the device stops outputting video stream. (goes to Output disable mode)

    ③When VID changes from 0 mV to 600 mV, the device still stops outputting video stream. (still in Output disable mode)

    The customer want to know why the mode does not transition from Output disable to Active even if VID changes

    from 0 mV to 600 mV.

    And the customer also wants to know the presetting of the register which will make the mode transition

    from Output disable to Active when amplitude recovers, in addition to the above settings.

    Please let me know.

    Best regards,
    Fumio Nakano

  • 0 in reply to F.N
    TI__Mastermind 19720 points
    What lanes are you changing from 0mV to 600mV the Squelch only looks at lane 0 to determine weather to go to the active mode. Also is HPD high the entire time that you are going from 0mV to 600mV?
    The register settings that you have above should be the correct registers to go from both active mode and output disable mode with the squelch event.
  • 0 in reply to Michael.Walker
    TI__Expert 8760 points
    Michael-San,

    Thank you for your reply.

    Sorry for the delay in response.
    I'm waiting for the customer reply.

    Best regards,
    Fumio Nakano
  • 0 in reply to F.N
    TI__Expert 8760 points
    Hi Michael-San,

    I appreciate your cooperation.

    I have not received the reply from the customer yet.
    I close this thread and will post as a new inquiry when I recieve the reply from the customer.
    Because I think your answer and comments are very helpful and the reply of the customer is too late.

    Thank you.

    Best regards,
    Fumio Nakano