About Rset value for LTC1799

Can I use LTC1799 as below for reduce Jitter?

 Voltage Supply:5V

 Pin 4:Floating

 Rset:2.4k Ohm

 

 Fmo:4.17MHz

 

Why is Rset minimum 5k Ohm at ELECTRICAL CHARACTERISTICS?

Best Regards,

  • 0
    •  Analog Employees 
    on Jun 8, 2021 5:35 PM

    This will not work for multiple reasons. First, the minimum Rset resistor is 5k. Smaller than 5k will result in internal currents running too high and saturating some internal nodes. Second, this would require the internal VCO to operate at 41.7MHz well beyond its 33MHz limit. Please note that these silicon oscillator parts are not particularly low jitter. They are fine for clocking switching regulators, switched capacitor filters and many digital systems, but they are not really even close to the jitter obtainable from a standard crystal oscillator. You could consider trying an LTC6905 running at divide by 4 giving 41.7MHz and then following this with discreate digital divide by 10 circuit. This would have lower jitter, but still not close to a crystal oscillator.