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ISOW7841: What are the internal switching frequency

Part Number: ISOW7841

We have a noise sensitive system and need to know what the internal switching frequency of the power supply and the OOSK carrier to make sure its out of band.

I assume the oscillator is always running even when there is a zero on the inputs?

thanks

tim

  • Hi Tim,

    Thank you for posting on E2E.  Minimizing emissions when designing with the ISOW7841 can be achieved by using techniques in the app report here. The device's internal oscillator is always on, but it only transmits across the isolation barrier when input signals are in the non-failsafe state; for the ISOW7841_, it's when inputs are low.

    Our ISOW expert will follow up soon with information on the internal frequencies. Have a good evening!


    Best,
    Manuel Chavez

  • Hi Tim,

    Hopefully all is well today. The ISOW78xx OOK carrier frequency is ~450MHz and the DC/DC converter switching frequency is ~60MHz. This device uses spread spectrum modulation to spread both of these frequencies into a band instead of single frequencies. This technique helps reduce emissions although the OOK carrier frequency strength is negligible on overall emissions compared to the DC/DC converter switching frequency.

    Please let me know if there is more information we can provide!


    Thank you for your time,
    Manuel Chavez
  • thanks,  This helps a lot.

    tim