• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 20 subscribers
  • Views 817 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMX2594: lock detect during automatic ramp

AY
Prodigy 180 points
Part Number: LMX2594


Hi,

I am using the following setting for check PLL lock detect:

MUXOUT_LD_SEL = Lock Detect

LD_TYPE = Vtune and VCOCal

It seems to work well when I was testing it for a fixed frequency where the signal when low (indicating 'Cal') to high (indicating 'locked'). However this is not the case when I am using running an automatic ramp. The signal seems to stay low all the time.

I would like to have a 'flag' out from the PLL to indicate the automatic ramp is started after writing the RAMP_EN bit. Is it possible with LMX2594?

Thanks. 

  • 0
    TI__Mastermind 28031 points
    Hi,

    If you set LD_TYPE = VCOCal, you can see if and when the VCO is calibrating. However, if you set Vtune and VCOCal, I don't know if this is really a reliable thing to ask as the VCO is not always in lock. I know we call it "Vtune", but it's really not based on the tuning votlage, but more the phase detector, so I could see why this is low.

    I don't see really any elegant way to do this.

    Regards,
    Dean