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TPS543820: Spread spectrum sync

Massimo Spadoni
Prodigy 30 points
Part Number: TPS543820

Hello team,

we are using the TPS543820 in a RF application.

Please, the device can be synchronized with an external Spread spectrum frequency clock?

If yes, which are the key parameters to keep in mind?

Any suggestion about a possible clock source device would be welcome.

Thank you

Kind regards

Massimo

  • 0
    TI__Mastermind 18370 points

    Hello Massimo,

    I have not tried to synchronize TPS543820 with an external Spread spectrum frequency clock before.
    TPS543820 is built to have low EMI using a butterfly construction, so the EMI emissions should be low even without dithering.

    But here are a few things about synchronizing with external clock that you should have in mind.

    1) TPS543820 can follow the frequency of an external clock only if the external frequency is close (within +/-20%) to the configured switching frequency (by Rfsel).
         Since the EMI measured in 10 KHz window, this (+/-20%) should be good enough in order to provide you with enough of peak attenuation db by dithering.

    2) TPS543820 follows the external clock frequency after 4 consecutive periods of the external clock. This seems to be fast enough in order to dither the ext. clk. frequency with a         25 KHz rate in order to avoid audible noise.

    3) The duty cycle of the external clock can be in range of 20% to 80%, but not narrower/wider.

    Hope this helps.

    Regards,

    Yitzhak Bolurian

  • 0 in reply to Yitzhak Bolurian
    Prodigy 30 points

    Hello Yitzhak,

    thank you for the quick and detailed reply, as it doesn't seem incompatible, we will check it on the next design phase.

    Kind regards

    Massimo