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DS90UB927Q-Q1: [DS90UB927Q-Q1]

MJ Jeon
Genius 5240 points
Part Number: DS90UB927Q-Q1
Other Parts Discussed in Thread: DS90UB940N-Q1,

Hi, TI Support Team

Customers are developing applications using the following products and mass-producing them.

Deserializer: DS90UB940N-Q1

Serializer: DS90UB927Q-Q1

Serializer and deserializer are respectively mounted on different boards, and it is a concept in which two products are connected to receive video signals to complete one product.

During mass production, some products have defects that do not receive video signals properly. In this case, the signal input to the deserializer is checked as low.

1. Is there any problem with the compatibility between the serializer and the deserializer currently being used?

2. The figure below shows the top marking of the normal part (Serializer) and the defective part (Serializer). Is there any difference in the characteristics of serializer chip parts? (I think there should be no difference.)

[Top marking of the normal part (Serializer)]

[Top marking of the defective part (Serializer)]

Please let us know if there is anything necessary to check the bad symptoms.

Thanks.

Regards,

MJ

  • 0
    TI__Guru** 103215 points

    MJ,

    The 927 and 940 are fully compatible with eachother and the only difference between the top and bottom device is the date code for when they were produced. There should be no functional difference outside normal process variance. Can you please provide more detail on your situation? Is the failing device always failing or do you have an intermittent problem?

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Genius 5240 points

    Hi, Casey

    1. Even the 927 board with malfunctioning works normally when linked with the 928.
    When connected to our 940 SET, video input is not normally performed.
    (Our 940 SET works normally when connected to other 927 boards.)

    2. When connected to 940, the phenomenon is that Lock is high but PASS is low.

    3. When the 940 output clock is connected to a normal 927, a waveform of 60Hz is displayed, but when connected to an abnormal 927, it is displayed strangely.

    Thanks.

    Regards,

    MJ

  • 0 in reply to MJ Jeon
    TI__Guru** 103215 points

    Hello MJ,

    Can you share information about your design so we can trace down the problem? If you can share the schematics for both 927 and 940N, then we can review to see if there is any obvious reason for this type of behavior. Again, from the part markings alone these devices are the same; just produced in different lots so they would have normal variation of performance within the datasheet specifications. 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Genius 5240 points

    Hi, Casey

    Thanks for your supports.

    There is a history of reviewing the 940 circuit diagram before.

    However, in the case of the 927, it cannot be obtained because it is not a part directly developed by the customer.

    Is there a common, common defect cause that causes the above symptoms?

    In analyzing the cause of the failure, which part should I approach and proceed with debugging?

    Personal opinions are welcome, and any opinions on general matters are welcome.

    Any advice would be appreciated.

    Thanks.

    Best Regards,

    MJ

  • 0 in reply to MJ Jeon
    TI__Guru** 103215 points

    MJ,

    Problems such as this could be caused by a variety of different things but at the most basic level, incorrect HW implementation such as wrong decoupling caps on PLL pins, incorrect PDB sequence, incorrect AC coupling caps, incorrect mode strapping could cause issues which is why I wanted to look at the schematics. If the 927 side is not produced by the customer and they do not have information about the design, how can they conclude that the boards with the 927 that is failing don't have other differences beyond the 927 device itself. Did the design change? Did the source video going to the 927 change? What is the difference between those boards besides the 927 device?

    From the SW side, is there any init control to the 927 or 940 through I2C? Can you probe the two board's I2C busses to check if the traffic is the same? Can you check the PCLK rate to the 927 to compare one vs. the other? Can you check if video parameters being applied to the 927 are the same in both designs?

    Best Regards,

    Casey