• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 23 subscribers
  • Views 223 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.

LMX2571: Locking the PLL using a presaler of 4

Daviel Almonte
Expert 3526 points

Part Number: LMX2571

We cannot seem to get the PLL to lock when using prescaler 4 on both the board and the demo board. Setting it to use prescaler 2 everything works fine and it lock all across our band. Just wondering if there is something we are missing on why we can't get this to lock.

  • 0
    TI__Genius 11900 points

    Hello Daviel,

    Are you using TICSPRO to configure the device? If so you can export your configuration by going to File->Export Hex Registers so that we can check to make sure everything is fine. When you change the pre-scaler to x4, to maintain the same VCO frequency you also need to divide your N-Divider by 2. Otherwise the VCO frequency will go out of range. Alternatively the Fpd frequency must be divided by 2 using one the input path dividers. Whenever changes to the PLL are made FCAL_EN must be written to 1. This is also an important step that shouldn't be overlooked.

    Thanks,

    Vibhu