• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 54 subscribers
  • Views 162 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.

CC1311P3: Temperature Sensor and Temperature Compensation

David Paden
Expert 1915 points
Part Number: CC1311P3
Other Parts Discussed in Thread: CC1312PSIP

Tool/software:

Hello,

I am working on the CC1311P3 and starting to look into temperature stability.  When reading through the documentation, I got the sense that there is some sort of automatic temperature compensation happening in the RF driver.  However, I can't find clear evidence of this mentioned in the reference manual.  The 2 items that made me think there might be some temperature compensation are these:

Section 25.3.3.2.16 and 25.3.3.2.17: "Each time transmission of a packet begins, temperature compensation of the transmit power is done"

and

Section 25.3.3.2.20: "On reception, the radio CPU sets the bus request bit toward the PRCM to 1 if bSysBusNeeded is nonzero, or to 0 if bSysBusNeeded is zero. If bSysBusNeeded is nonzero, this indicates that the system bus stays awake even if the system goes to deep sleep, which must be done for the RF core to run and access the system side for one of the following reasons: • Any command structure, data structure, and so on, pointed to by a pointer sent to the RF core is placed in system RAM or flash. • The RF core must read the temperature because the TX power has a nonzero temperature coefficient. • The RF core must read the RTC to synchronize with the RAT during CMD_SYNC_STOP_RAT or CMD_SYNC_START_RAT."

Is the RF core automatically supposed to be handling the temperature compensation?  If so, are there any user requirements for it to work properly (user software requirements to enable the temperature sensor, for example)?  Or is the temperature compensation NOT automatic and must be handled by user software?

And a last question: Is there any any temperature compensation for the frequency synthesizer?  I don't see any text in the manual regarding frequency compensation.

  • 0
    TI__Genius 17865 points

    Hi,

    Yes, as you note in Section 25.3.3.2.16 and 25.3.3.2.17 there is basic temperature compensation of the transmit power. This is also described in Section 10 of SWRA640 (CC13xx/CC26xx Hardware Configuration and PCB Design Considerations): https://www.ti.com/lit/swra640 - the most important sentence of which for your question is:

    The temperature coefficient is applied to automatically compensate the IB setting based on the temperature readout of AON_BATMON_TEMP.

    Regarding the frequency synthesiser, for large shifts in temperature the synth has to be recalibrated using the CMD_FS command. This must be done by the user and is not done continuously during TX.

    The frequency tolerance over temperature of the HF crystal used will also have a large impact (and is consequently also dependent on HW) used - selecting the appropriate crystal for your specifications is important. I cannot comment on timelines or delivery commitments publicly, but a "Software TCXO" (SWTCXO) feature has been successfully implemented on the CC1312PSIP, and we are now investingating an implementation that customers can use on the CC131xRx/CC131xPx devices. If so, this will add an additionally degree of temperature-dependent frequency offset compensation. 

    Regards,

    Zack