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DS90UB960-Q1: 960/953 can't LOCK at power up

Betty Guo
Expert 7300 points
Part Number: DS90UB960-Q1

Hi team,

customer use 960 with 2*953. they found sometimes, one PORT of 953 can't LOCK with 960. they also use external POC circuit to power supply, the issue is still remain.

this is dump reg of 960, first is normal reg value, the second is can't LOCK reg value. I also attached customer schematic, can you help to check it? thanks.

ds90ub960原理图.pdf

  • 0
    TI__Genius 11340 points

    Hi Betty,

    It looks like you have initially lock but the lock was lost during the operation? If you repeatedly read reg 0x4D, do you see lock restoring and dropping again?

    Can you run the margin analysis tool? You can refer this app note for more details: 

    Best,

    Jiashow

  • 0 in reply to Jiashow Ho
    TI__Expert 7300 points

    Hi Jiashow,

    yes, it is locked initially, then LOCK lost. but during this time, the software didn't do any action to 960.

    1 pcs 960 pair 2*953, only one PORT occur lock lost, for example PORT2. another ports, such as PORT3, the LOCK status also be change, but never lost.

    after lock lost, repeat read 0x4D, the lock lost status can't be clear.

  • 0 in reply to Betty Guo
    TI__Genius 11340 points

    Hi Betty,

    Based on my understanding, after lock is lost it is never recovered? Are you seeing this issue occurring always on one specific port?

    If this is the case, can you check the PoC power and probe the 953 power pins to make sure the 953 is powered?

  • 0 in reply to Jiashow Ho
    TI__Expert 7300 points

    Hi Jiashow,

    yes, if LOCK is lost it never recovered. customer have test can make sure the POC power and power supply is OK.

    in addtional, when the device unlock, they reset 960, the 953 and 960 can transmit normally. can you comment what's the reason?

    below is power up sequence:

    1. first power up 3.3V, waite 400ms, power up 1.8V, then power up 1.1V. PDB is high.

    2. then, pull down PDB  2~3ms, configure 960.

  • 0 in reply to Betty Guo
    TI__Genius 11340 points

    Hi Betty,

    Even when the PoC is okay, are the individual rails to the 953 okay too?

    For the power up sequence, do PDB come up after all the other supplies are stable? And PDB was pulled-down and then pulled-up again?

    Best,

    Jiashow