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CC1120: Using 38,4MHz TCXO for CC1120

Knud Tangsgaard
Prodigy 80 points
Part Number: CC1120
Other Parts Discussed in Thread: CC1125,

Hello

We are using CC1125 for 12,5kHz narrow band application at 869,212MHz (Social Care under EN300-220), and using a 38,4MHz TCXO clock.

Supply voltage= 3,3V

Have found that CC1120 is nearly identical to CC1125, but only specified to using 32MHz crystal.

 

We have tried to replace a CC1125 by CC1120, and did keep the 38,4MHz TCXO clock.

I seems to work fine Blush

Questions:

  1. For what reason are crystal frequency for CC1120 limited to 32MHz?
  2. What is the consequence of feeding a CC1120 by 38,4MHz from TCXO?

Regards Knud

  • 0
    Mastermind 6640 points

    The CC1120 is not designed for a 38.4 MHz TCXO. It's the ADC in the receive chain that sets this since the ADC will not be stable for all conditions with 38.4 MHz reference. On CC1125 it's an extra bit that makes it possible to reconfigure the ADC to be stable on both 32 MHz and 40 MHz.