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CC1310 with TXCO?

pixbroker
Genius 5820 points
Other Parts Discussed in Thread: CC1310, CC1350

Can CC1310 be used with a 24M HCOMOS output TCXO and powered from internal DCDC_SW? 

  • 0
    TI__Guru**** 317180 points
    As I have understood it powering the TCXO from DCDC_SW could cause issues when the chip is in one of the power save modes due how the internal power supply system is built.

    CC13xx can be clocked by a TCXO, the external clock must be connected to the X24M_P pin. X24M_N should be left unconnected. There are also some register settings required (I don't have the full overview here at the moment)
  • 0 in reply to TER
    Genius 5820 points
    Thanks for the info. The bit about not being able to use the internal DCDC is unfortunate but noted. Do you have any suggestions on how to intelligently power manager the TCXO? They usually draw ~2mA so one wouldn't want to have this on all the time. What is a good metric on when this needs to be powered and when it's ok to turn it off?
  • 0 in reply to pixbroker
    TI__Guru**** 317180 points
    One option could be to power the TCXO from a DIO and route a internal signal to the DIO to set it correctly. This is not something we have looked at in detail. This solution limits you to 3.3 V but it's a chance we can support 1.8 V in the future.
  • 0 in reply to TER
    Genius 5820 points
    I would be interested in more details about the "route a internal signal to the DIO to set it correctly". either powering from DIO directly or having DIO enable an external DCDC sounds ok. Thanks.
  • 0 in reply to pixbroker
    TI__Guru**** 317180 points
    Check the CC26xx TRM, the internal signals on CC13xx are the same. I think using a DIO could be a possibility but have not looked into the details. Using a DIO to enable a TCXO should be fairly straight forward since a xtal source is not needed to boot up and it should be possible to set the DIO before/ after starting/ stopping the RF code.
  • 0 in reply to TER
    Genius 5820 points

    TER,

    sorry, i have to follow up on this. Via our sales contact, we had placed the same question and got the following response:

    "Currently the software cannot support TCXO’s, the CC1350 does not support ultra-narrow band anyway so I am questioning the need for a TCXO I think a good XTAL could do the job just fine."

    Can you reconfirm that a TXCO can be used on RF_P as we discussed above?

  • 0 in reply to pixbroker
    Expert 1960 points
    Hello TER,
    We faced the same problem providing clock to CC1310. It is not clear if we can use external TCXO. What conditions are for powering TCXO by CC1310 using DCDC_SW or DIO (register settings, etc.)? Are any limitations if we power up TCXO from external, not controlled by CC1310 source? Do you have any Application notes?
    Thanks,
    Alex
  • 0 in reply to TER
    Expert 1960 points
    Hello TER,
    We faced the same problem providing clock to CC1310. It is not clear if we can use external TCXO. What conditions are for powering TCXO by CC1310 using DCDC_SW or DIO (register settings, etc.)? Are any limitations if we power up TCXO from external, not controlled by CC1310 source? Do you have any Application notes?
    Thanks,
    Alex
  • 0 in reply to Alex Strelbytskyy
    TI__Guru**** 317180 points
    Correction to my first post: The hardware on CC1310 is not designed for a TCXO meaning that the device doesn't have a built clock qualifier. CC1310 requires that the 24 MHz XTAL clock signal is stable when switching to it from the 24 MHz RCOSC signal. CC1310 has checks to ensure that the xtal is up and running before switching clock source but the chip has no mechanism to ensure that a TCXO signal is stable before switching. If the clock is not stable the device could be bricked. TCXOs may not have a stable clock signal when they are powered on.

    The short of it: We don't support TCXO on CC1310/ CC1350.