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LTC6954 Minimum Input Frequency

Hello,

I'm trying to sync a 0.4Hz signal (200ms pulse width), that's why I'm interested in the minimum input frequency of the LTC6954.

Since there is no minimum value given in the datasheet, I assume, it will work with 0.4 Hz on the inputs (IN+, IN-) as well as 200ms pulsewidth on the sync input.

Is this assumption correct?

  • It can work on IN+/-, if you your input signal has reasonably fast rise and fall times.  For instance, a sine wave would be too slow through the hysteresis region of the input and cause some false toggling.  You'll probably need to DC couple rather than AC couple with that slow of signal.

    Sync requires >= 1ms pulse per the datasheet.  Let me get back with you as you may need several input cycles to synchronize the outputs.  What divide settings were you planning on use?  I'll need this to discuss with our designers.

  • Thanks for the quick response!

    In this application, there is no need for frequency division, so it would be 1. The edges of the 0.4 Hz signal should be sufficiently fast.

  • You're welcome.  Thanks for considering our parts!

    In divide 1 mode, there is not a need to synchronize the LTC6954 dividers for phase alignment.  All the outputs will be in phase with a /1 setting.