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ISO1640: ISO1640

Part Number: ISO1640

Dear support,

I have red the datasheet of ISO1640 I2C driver and I get a question about the content of §8.3 of it (page 31/58):

Could you please provide me the frequency of the carrier used to transmit the data from the two sides of the driver?

Have you got any EMI measurement showing the radiation from this component (near fied or far field)?

Hope to get an answer from you.

Best regards.

Pierre Bruot

  • Hi Pierre,

    Welcome to TI E2E forum and thanks for showing interest in ISO1640.

    The frequency of the OOK carrier used in the device is 450MHz. This is the same carrier frequency used across many TI digital isolators which we have tested most of these devices for CISPR 32 and we do not see the 450MHz impacting the results for any of the devices.

    I hope that answers your question. If you see any concerns due to the frequency, please do let me know. Thanks.

    Koteshwar Rao

  • Hi Koteshwar,

    Thanks for this first answer.

    We do not have to comply with civil standard but military which are more severe.

    Have you got any EMC results that you can share with us?

    Do you get any document describing the test configuration and any recommandation to minimize the radiated disturbance coming from the component?

    Best regards.


  • Hi Pierre,

    Thanks for clarifying on your requirements. I am not familiar with the military standards and requirements and we have not tested ISO164x for such standards either.

    Please find below the radiated emissions test result of ISO1640 as per CISPR 32. I do not have a document describing the test setup but the test conditions are described in the below image stating that ISO1640 was tested by applying 400kbps clock signal on both SDA and SCL lines and a 1m cable was connected on Side2 lines (SDA2 and SCL2) of ISO1640 to replicate actual worst-case test conditions.

    As you can see, the device has no frequency components showing up in the spectrum. A few small spikes you see are not related to ISO164x and are probably due to some other component elsewhere.

    I do not have a dedicated document describing ways to minimize radiated emissions from ISO164x but the below application note on a different ISO device lists some of the methods that can be used to improve emissions for isolators. The methods described in this application note are equally applicable for ISO164x as well although we find them to be not necessary as we believe the device doesn't pose any emissions challenge.

    Low-Emission Designs With ISOW7841 Integrated Signal and Power Isolator (Rev. C)

    Let me know if you have any further questions, thanks.

    Koteshwar Rao

  • Hi Koteshwar,

    I'm surprised to not see on the plot a spike at carrier frequency (450 MHz). But it is a good surprise.

    We will expext to do some specific EMC test on our product as soon as it will be designed. If we get strange result I will contact you (could you please send me your email adress in rder to share with you the results?).

    In your last answer you are talking about an application note, which one is it?



  • Hi Pierre,

    Yes, the power level of internal carrier is significantly lower compared to a typical switching power supply. Hence, it doesn't cause any radiated emissions issue.

    Regarding the application note, sorry I missed to include link to the application note I was referring to. I have updated my previous post with the link now, you should see it now.

    Regarding future support, I would request you to reach out over E2E for fastest support. There are multiple people assigned to provide fastest support on E2E. If you have an information that you do not feel sharing publicly, then do let us know at that time and allow us to reach out to you on your email and one of us can write to you accordingly. Thanks.

    Koteshwar Rao