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Original question:

LMX2594: ramp generation

LMX2594: Phase synchronous ramping and calibration question

Bruce Frantz
Prodigy 80 points
Part Number: LMX2594

Is it possible to have phase synchronous ramping of multiple LMX2594s?  

What happens when multiple devices are ramping together and the ramp cannot be done calibration free?  Is all of the calibration guaranteed at the same time, in lock step?  What happens to the output during cal?

  • 0
    TI__Mastermind 27981 points

    1537.LMX2594 Calibration Free Ramping.pdfBruce,

    In general, during the ramping, the output is slewing and therefore you can not assume that two devices that are ramping at the same time will be phase coherent.

    You can force the calibration to take a certain time and to happen at certain intervals, but if this interval is too low,  or hte time is too short, then the VCO will calibrate as long as it needs to and as often as it needs to.  The attached document discusses how often the ramp needs to calibrate.

    There is the OUT_FORCE bit that forces the output to be on during calibration (otherwise it turns off).  However, for frequency ramping, you need to have OUT_FORCE=1, so the output will be always on.

    Regards,

    Dean