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CC2642R-Q1: Inquiry about recommended 48MHz crystal

Part Number: CC2642R-Q1

Hello Experts,

Our customer selected NX2016SA(48MHz ,CL=7pF, ESR=80 ohm ) and they’re developing their module currently. Customer shared their module with crystal maker and they were requesting them to check if there were any problems or not. According to crystal maker’s comments, for Negative resistance (RN) parameter, they mentioned it did not meet this crystal’s requirement. This means, crystal maker mentioned, it seems that the negative resistance is recommended to be 300ohm or more when using this crystal. Therefore, customer is asking any advice/comments on this behavior to TI, and then, customer would like to know TI's recommended crystal parts name. Can I have any advice/comments on this, please ?

First of all, I shared the following documents.

“Crystal Oscillator and Crystal Selection for the CC26xx and CC13xx Wireless MCUs” ( )

I really appreciate your help.

Best regards,


  • HI Miyazaki-san,

    Tai'saw's TZ2365D is our recommended 48MHz crystal for this device. Regarding the negative resistance, we recommend that ESR is 3 time greater than the magnitude of the negative resistance. While a negative resistance of 260 to 280 technically meets this requirement with ESR = 80 a value of 300 would give enough margin to ensure functionality across temperature ranges and other environmental factors. See image below.

    Best regards,


  • Hi Bun san

    Thank you for answering.

    For this result, we used the recommended crystal: NX2016SA-48MHz-EXS00A-CS05517.
    The ESR of the crystal is 40Ω (maximum), so a stop of oscillation of 260Ω (temperature = 105°C) is six times.
    A crystal maker (NDK) has reported that 300Ω or more is desirable based on experience.

    But I think your results are good enough considering the temperature margin.

    I think it's okay if the oscillation stop resistance is at least 5 times the ESR.
    What do you think of this idea?

  • If that is the case, then 260 - 280 negative resistance should be sufficient. All is good. Is the manufacture quoting -300 ohms to be conservative or it is a yield issue or something else?


  • NDK requires a margin for results based on experience.

    The required value of 300 Ω is the result of their calculation based on their prediction of the market defect rate using their own calculation formula.

    NDK is asking whether it can be improved with the IC setting value (Cap-Array Delta).