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DS90UB940-Q1: LOCK pin shows 0 (PLL is unlocked)

Guru 29720 points
Part Number: DS90UB940-Q1
Other Parts Discussed in Thread: DS90UB925Q-Q1,

Hi Team,

My customer is evaluating DS90UB940-Q1 with DS90UB925Q-Q1 and found sometimes LOCK pin of DS90UB940-Q1 shows 0 (PLL is unlocked).
Could you tell me the condition that LOCK pin shows 0?

My customer especially wants to know if there is the condition that the signal quality of FPD-LINKⅢ is no ploblem in this case.

Best Regards,
Yaita / Japan disty

  • Hello,
    Is the LOCK sometimes low or always low? If its static low, check if the clock/data/sync is present at the serializer input, cable is connected with correct polarity and if the differential signal is present at the deserializer input. If LOCK is toggling that can be caused by poor quality of PCLK input (too much jitter), power supply noise etc. You can also measure the serializer output and the CMLOUT eye on deserializer.