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LMK61E2 - dynamically changing frequency via I2C

Manuele Rusci
Prodigy 10 points

Other Parts Discussed in Thread: LMK61E2

Hi E2E,

I'm pointing to the LMK61E2 oscillator to feed a digital processor circuit (equipped with LVDS clock pad). My intention is to dynamically varying the oscillator output frequency via I2C by using an external microcontroller. From the datasheet, it is not clear to me what is the correct procedure to achieve my scope when the oscillator is in integer mode. Could you please provide me some indications?

For now, I'm doing the following steps:
1. Setting the dividers OUTDIV e NDIV
2. Enable frequency calibration , by asserting bit 1 of R10
3. Waiting lock by checking bit [1:0] of R66
Is it wrong ?

  • 0
    TI__Expert 4415 points

    Hi Manuele,

    Yes, your procedure is correct. You do not need to run frequency calibration after changing these settings.

    Also, updating OUTDIV should not cause the PLL to lose lock as the output divider is after the VCO output.

    Regards,

    -Tim