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Original question:

CC1310 24 MHz Crystal Specifications

CC1310: cc1310 24MHz crystal specification?

Brad Buike
Prodigy 110 points
Part Number: CC1310

Hi,

We need to specify a new 24MHz crystal for the cc1310 as the current one is on a long lead-time. Checking the 24MHz spec in the cc1310 datasheet, it does not mention the maximum frequency tolerance and frequency stability. Please can you let me know the maximum tolerance for those 2 parameters? We have a candidate but the tolerance is +-/ 25ppm and the stability is +/-50ppm.

Thanks,

Brad. 

  • 0
    TI__Mastermind 27145 points

    Hi,

    We used TSX-3225 24.0000MF15X-AC3 (CRYSTAL, 24MHz, -15PPM/DEGC/+15PPM/DEGC, -40DEGC/+85DEGC, SMD) from Epson on our reference design. You can use equivalent of it.

    Attached is the Epson Data sheet.

    FA-238V-24MHz_en.pdf

    Thanks,

    PM

  • 0 in reply to PM
    Prodigy 110 points

    Hi,

    Thanks for the suggested crystal, but this doesn't really help us. We still need to understand what will happen to the output if the frequency tolerance is +/- 15ppm and the frequency stability is +/- 50ppm?

    Thanks,

    Brad.

  • 0 in reply to Brad Buike
    TI__Mastermind 27145 points

    Hi,

    Frequency Tolerance (+/- 15ppm) means the maximum allowable Frequency deviation from the nominal frequency at an Ambient Temperature +25C.

    Freq Stability (+/- 50ppm)  means  the maximum allowable Frequency deviation from the nominal frequency over the operating Temperature range (-40 C tp +85C? - Specified by the Mfr).

    Any Frequency tolerance in the Crystal translates into the RF Frequency accuracy of the device.

    For example, +/- 15ppm means, it could be +15Hz / -15Hz for every 1MHz.

    For 900MHz RF Freq, 915*15 = 13725 Hz = 13.725KHz. So, the RF Freq could be any where from 915 MHz +/- 13.725 KHz. If you have the Crystals from different batches, then the Transmitter could be at 915 MHz+13.725KHz and the Receiver at 915MHz - 13.725KHz. That means the Transmitter and Receiver could be 27.45KHz from each other. If your Receiver Bandwidth is not wide enough to accommodate this frequency error then it will loose reception.

    You can calculate the same  to 50ppm. For 50ppm, the Transmitter and Receiver could be at 91.5KHz away to each other at 915MHz.

    Hope this helps for your understanding and selection of the crystal.

    Thanks,

    PM