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Original question:

TLK2711-SP: Power-On Reset

TLK2711-SP: Follow-on Questions to TLK2711-SP Power-On Reset post

Michael Koval1
Prodigy 10 points
Part Number: TLK2711-SP
References:

  1. TLK2711 Serdes EVM Kit Setup and Usage - User's Guide (Link on TI website is https://www.ti.com/lit/ug/sglu001a/sglu001a.pdf?ts=1612823303889&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252FTLK2711EVM-CVAL)
  2. Reference figure below showing planned use of TLK2711.


In Mark Philip Felipe's original posting (Question #2) he asked:
If the Power-On Reset is properly executed, is it still possible for the receiver circuit to arrive in this failed state?
Nasser Mohammadi Answered:  Yes. However, to get around this for sure, LCKREFN and LOOPEN need to be de-asserted at least 1ms (however, TI suggest 2ms to provide margin) after stable power.
I have a FOLLOW-ON Question to Question #2: 
Given the planned use of TLK2711 (See Figure above), AND assuming there is NO active data present at RX+/RX-, will the de-assertion of both LCKREFN and LOOPEN (as prescribed by Nasser above) still result in a successful power up (i.e. WITHOUT internal contention).
Also, in Mark Philip Felipe's original posting (Question #3) he asked:
Is there a way to monitor status such that one can confirm that the TLK2711-SP is NOT in this failed state?
Nasser Mohammadi Answered: LCKREFN and LOOPEN de-asserted plus pulses on RXN/P.
Again, I have a FOLLOW-ON Question to Question #3:
Again, assume the planned use of TLK2711 is as shown in the above figure, with valid data at RXN/P and both LCKREFN and LOOPEN de-asserted, is there a pin(s) on the TLK2711-SP that may be monitored that will tell me that the TLK2711-SP IS or IS NOT in this failed state?
Thank you for your help on this.
  • 0
    TI__Guru* 93670 points

    Hi Michael,

    I believe the issue is that device receiver needs to see data transitions during power up. This can be accomplished - during power on reset - either through activating LOOPEN or if there is activity on receiver while LOOPEN is not asserted. Now getting back to the usage model you noted:

    1). Given LCKREFN and LOOPEN are not asserted AND there is no active data on RX+/RX- this may not result in successful power up. This is because device needs data transitions to get the PLL up and running.

    2).  With valid data on RXN/P and de-assertion of the LOOPEN and LCKREFN, transitions on stable RXCLK would indicate normal operating mode.

    Regards,, Nasser