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LMX2491: How do i feed start and stop frequency of sawtooth continuous ramp

Alok Sahu
Prodigy 230 points
Part Number: LMX2491
Other Parts Discussed in Thread: TICSPRO-SW

I have a custom board of LMX2491. I have difficulty in understanding what register value should i feed for RAMP_CMP0 and RAMP_LIMIT_LOW and RAMP_LIMIT_HIGH. I have read the datasheets. I have understood to enable the ramp, have to select RAMP_CLK, I have RAMP_PM_EN = 0, configured RAMP0_INC, RAMP0_LEN, RAMP0_NEXT = 0 (Ramp 0), RAMP0_NEXT_TRIG = 0 (Next Ramp starts immediately) but unable to understand how to feed the start and/or stop frequency.

Help in this regard is appreciated.

Thanks,

Alok

  • 0
    TI__Mastermind 27911 points

    Alok,

    I highly encourage you to try our TICSPro software and the LMX2491 Ramp GUI that does all these calculations for you.  It is available at ti.com/tool/ticspro-sw

    The starting frequency is based on the VCO frequency when ramping is disabled.  Then if you take RAMP0_INC and RAMP0_LEN, the ending frequency is implied by the change in frequency.  The TICSPro software calculates this for you.

    Regards,

    Dean