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LMK61E2: Synchronizing multiple LMK61E2

Part Number: LMK61E2
Other Parts Discussed in Thread: CDCE6214-Q1, LMK04832, LMK04808, CDCI6214

Hello,

I am considering using two LMK61E2 devices, but I was unable to find anything in regard to synchronizing multiple devices. Since there is no reference, it looks like this is not possible. Is it possible to use the OE pin (considering trace length,etc...)? Do you have a suggestion in regard to another device that can provide two outputs (looking to save power) while offering fractional PLL with a similar frequency output of the LMK61E2? Thanks!

Best Regards,

Dan

  • Hi Dan,

    I'll check with the designer whether or not OE pin resets the output divider. If it does, then theoretically it should work, but if OE pin only mutes the output, then it won't work. Typically the way we do this is to either use a SNYC pin, or use zero delay mode. Here's a draft version of appnote that explains this in detail: 6177.Multi LMK0482x SYNC, for customer, pre-release draft 2019-01-23.pdf

    Typically we recommend devices newer than LMK04808. LMK04832 is the most recommended. But those seem to be too complicated for your use case. CDCE6214-Q1 also supports both SYNC pin and zero delay mode, and it's small and cheap enough so you can take a look at that one.

    Regards,

    Hao

  • Hello Hao,

    Many thanks for suggesting the CDCE6214-Q1. This is a compelling product that may fit my needs. Do you know when this part is expected to be released? How would I go about ordering an EVM? I took a quick look at the CDCI6214 (since I don't require automotive qual). Do you think this would be a valid substitution?

    Please let me know when you find out about the LMK61E2 synchronization. Thanks!

    Best Regards,

    Dan

  • Hi Dan,

    Just confirmed with designer. OE pin only powers down the output buffer. It doesn't reset output divider so it won't work for output synchronization. CDCI6214 only supports integer mode and CDCE6214-Q1 has fractional PLL.

    The device will be fully released in about 2 weeks.

    Regards,

    Hao