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DS90UB948-Q1: DS90UB948：How to perform the BIST

?? ??
Prodigy 140 points
Part Number: DS90UB948-Q1
Other Parts Discussed in Thread: ALP

Tool/software:

Hi,

We are using the DS90UB948 and DS90UB927 for communication. After reading the datasheet, I executed the BIST using the ALP tool following the steps below.

With a stable connection, there were 0 errors over 1000 seconds, while with an unstable connection, there were 255 errors over 40 seconds.

Given the extreme results, I am questioning whether the BIST method is correct. Are the steps correct?

Steps:
1. Write 0x00 to address 24h.
2. Write 0x03 to address 24h. *BIST starts
3. Write 0x00 to address 24h. *BIST ends
4. Read address 25h. *Check error count.

Best,

  • 0
    TI__Expert 3234 points

    Hi,

    Can you elaborate more on the conditions of the stable and unstable link? i.e what is the loss on the unstable link?

    I would expect the errors to increase in an unstable connection, the rate of error accumulation will depend on how unstable the link is - the results may only be extreme if the unstable connection is within our provided channel specification.

    ?? ?? said:
    Steps:
    1. Write 0x00 to address 24h.
    2. Write 0x03 to address 24h. *BIST starts
    3. Write 0x00 to address 24h. *BIST ends
    4. Read address 25h. *Check error count.

    Prior to startup, pin 16 must be strapped HIGH and pins 16,17,18 must be strapped low as specified by x948 datasheet shown below:

    Prior to the code sequence shown, you have to enable PORT1_SEL for the correct output port.

    Thanks,

    Ragav Subramanian

  • 0 in reply to Ragav Subramanian
    Prodigy 140 points

    Hi,

    I will send the MAP results for stable and unstable connections.

    Regarding the implementation method of BIST, the data sheet describes two methods: ① pin setting method and ② register setting method.
    *Refer to the image.
    Is this method acceptable for the register setting case?
    Steps:
    1. Write 0x00 to address 24h.
    2. Write 0x03 to address 24h. *BIST starts
    3. Write 0x00 to address 24h. *BIST ends
    4. Read address 25h. *Check error count.

    Since the MAP has been executed, I believe PORT1_SEL is functioning correctly.

    Best,