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LMR23630: Sync pin behavior on fixed-frequency versions

Andrew Berry
Prodigy 50 points
Part Number: LMR23630

On the fixed frequency versions, can the En/Sync pin be used to override the default fixed 400kHz switching frequency and run the part at ~2MHz?  The datasheet doesn't explicitly indicate one way or the other.  Nothing in the text that I can find says that this isn't possible, but I don't want to assume!

  • 0
    TI__Mastermind 25590 points

    Andrew,

    Section 8.3.4 of the datasheet details the EN/SYNC behavior and Section 7.7 of the datasheet states TSYNC_MIN (Minimum sync clock ON-time and OFF-time) of 100ns typical. So 2MHz is definitely possible.

    -Sam

  • 0 in reply to Samuel Jaffe
    Prodigy 50 points

    I saw that, but, while it does not imply that you can't  run the fixed versions at 2.1MHz via the Sync pin, it also doesn't necessarily mean that you can (since obviously min on/off times at the sync input are are only one possible limiting factor on frequency).  

    Also, interestingly, the Webench configurator allows a user frequency of up to 2.1MHz on the adjustable parts, but allows a Sync frequency of only up to 1.2MHz, but on both the adjustable and the non-adjustable parts (which directly contradicts the datasheet at least where the adjustable parts are concerned, which says they can sync up to 2.2MHz). The max sync frequency I guess is simply wrong in Webench.  The fact that Webench allows the fixed parts to be Sync'ed up to the same frequency as the adjustable parts is encouraging, but it would still be better if the datasheet explicitly stated the functional range of the sync pin on the fixed parts rather than simply implying it.

  • 0 in reply to Andrew Berry
    TI__Mastermind 25590 points
    Andrew,

    Thanks for pointing this out. I'll get in touch with the WEBENCH team to clear this up.

    Thanks again,
    -Sam
  • 0 in reply to Samuel Jaffe
    TI__Mastermind 25590 points
    Andrew,

    We have fixed this internally. It will reflect online after our next refresh (a couple weeks). Thanks again for pointing this out.

    -Sam