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LMX2581: partial power down mode

Lilian Chang
Intellectual 1555 points
Part Number: LMX2581

Hi Team,

When out of the partial power down mode, if it is necessary  to program R0 again to activate the frequency calibration? 

When out of the partial power down mode, frequency keep the same as before, do they still need to program R0?

My customer found it can lock without any SPI writes only CE pin control, is that make sense?

Thank you.    

 

  • 0
    TI__Mastermind 28011 points
    Lilian,

    According to the datasheet, R0 should be reprogrammed.

    That being said, we are being conservative in saying this. The VCO should retain its calibration information and therefore lock. However, there could be other things that might cause issues. For instance, if you use a fraction of 1000000/4000000, you might find the fractional spurs are nice, but if you toggle CE pin, you could create a mess of fractional spurs. Also, we are not sure about the automute feature of the lock detect.

    So this should work, but just be aware that this can potentially cause some issues with some of the features like lock detect and also cause fractional spurs (but not if you are not in fractional mode).

    REgards,
    Dean
    Regards,
    Dean