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DS90UB948-Q1: DESER 948 LOCK Pin Issue

Shubham Jagtap
Prodigy 110 points
Part Number: DS90UB948-Q1
Other Parts Discussed in Thread: DS90UB949A-Q1

we are working with DS90UB948-Q1 which is on our Board and DS90UB949A-Q1 ( Client Board).

 

We are facing one issue –

In normal operation – LOCK Pin drive high

In Blinking Condition - LOCK Pin is toggling from High to Low when there is Display Blinking Condition (BKLT Remain ON but display blink on TFT Display).

 

So we want to know, what is possible reason to happen this condition – is this pin is dependent on SER 947 condition?

Kind Regards,

Shubham 

  • 0
    Prodigy 110 points

    Hello Concern,

    Title name - Is got wrong - 

    it should be DS90UB948-Q1: DESER 948 Lock Pin Issue

  • 0 in reply to Shubham Jagtap
    TI__Guru** 103215 points

    Shubham,

    The LOCK signal indicates that the deserializer is able to identify the forward channel FPD-Link signal from the serializer (DS90UB949A-Q1 in this case). If the LOCK pin is toggling, that means that the deserializer has a weak/intermittent link with the remote SER which could be related to the serializer HW, deserializer HW, or the cable in-between the two. 

    Is this issue occurring on a specific set of HW? Or is it one set of HW that occasionally powers up with an issue? Have you tried swapping the cable in-between the SER/DES? What PCLK rate is being used here? 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Prodigy 110 points

    Hello Casey,

    Thanks for the info. Weak/Intermittent Link means - Physical Link or unstable video Input over link?

    This issue occurring on multiple HW.  PCLK Rate is 48MHz in our application.

    Kind Regards,
    Shubham 

  • 0 in reply to Shubham Jagtap
    TI__Guru** 103215 points

    Hello Shubham,

    LOCK is related to the data link between the SER/DES which includes video data, control/status data, GPIO, I2C, etc. 

    So you are saying this issue does not follow the cable if the cable is swapped out in the setup? What kind of cable/connector is being used here?

    If you would like further help on this I will likely need to look closer at the design and char data for the system here including both SER/DES. I would recommend to start by providing your schematics so we can review that and see if there are any obvious issues.

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    TI__Expert 5940 points

    Hello Casey,

    I have aligned with Shubham and his team: they are not comfortable with sharing their schematic on the public forum, so I will be continuing the discussion with you in private.

    Best regards, Antoine