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TRF7960A Minimum Crystal Requirements (>± 20 ppm )

Prad1
Genius 3825 points
Other Parts Discussed in Thread: TRF7960A

Hi,

Regarding the TRF7960A Crystal Requirements.
According to the datasheet we understood that the Frequency tolerance should be
±20ppm for the full operating range.

Our customer is using clock oscillator and because of the
current availability issue, they are not able to find oscillator with ±20ppm tolerance.

Instead they are using oscillator ±25ppm tolerance.

Could please let us know what could be the consequences if we
use ±25ppm clock with TRF7960A? Should we use only ±20ppm clock?

Best Regards
Prad

  • 0
    TI__Mastermind 38620 points

    Hi Prad,

    The crystal frequency is what is used to generate the carrier.  The ISO and EMC specifications say that the carrier must be 13.56MHz, +/-7kHz.  This means the range is from 13.567MHz to 13.553MHz.  This equates to a much larger ppm rating of ~516.  Handy calculator below.

    http://www.jittertime.com/resources/ppmcalc.shtml

    We indicate 20ppm as a recomendation in the datasheet to ensure a high quality product with no issues.  The +/- 25ppm oscillator should work fine, but they should verify their design to be sure that the frequency variation will never deviate greater than +/-7kHz over both temperature and time.

       

  • 0 in reply to Eddie LaCost
    Genius 3825 points

    Hi Eddie,

    Thank you so much.
    Actually we found that,in Japan RF Regulation it should be less than 50ppm.
    We have requested the customer to use the clock near to the datasheet spec.

    Best Regards
    Prad