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LMK04832EVM: If LMK04832 can support modify the frequency but do not need sync

Yuxi Liu(Tony)
Expert 4370 points

Part Number: LMK04832EVM
Other Parts Discussed in Thread: LMK04832

Hi TIer

My customer using the LMK04832EVM to output 2ch 40MHz from 2 dividers , and then they want dynamically to modify the registers and set output 80MHz, but wants to maintain latency.

We use EVM test it and find:

  1. If SYNC is not used, the relative delay of the outputs of the two dividers will change (is this expected , I think) 
  2. The customer's dilemma is that sending SYNC will cause other output interruptions, so they don't want to use SYNC. 
  3. So the customer would like to know if there is a way to dynamically change the frequency but not using sync, like configuring a register at the same time? How do I get it on the EVM board? We tried the Write All Register button on TICS PRO, but the effect was the same.

Thank you very much.

 

  • 0
    TI__Mastermind 35040 points

    This is not possible with LMK04832 because the dividers are internally reset any time the registers controlling them are written, and the reset timing is a function of the (asynchronous) internal digital state machine clock. To my knowledge, there are no devices in our portfolio that are capable of switching a 40MHz clock to an 80MHz clock while maintaining the original phase relationship. However, you could emulate this effect with an externally-controlled analog mux or an RF relay, by switching back and forth between two phase-aligned clocks pre-synchronized at 40MHz and 80MHz.