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ISO6720: Downconverting digital signal with elevated ground

Part Number: ISO6720

I am in need of a solution to downconvert a digital signal from one voltage domain to another.  The input signal is a square wave with 1.8V pk-pk amplitude, but its ground reference (logic low) will be anywhere from 0V to 5.6V. (So the square wave could be from 0-1.8V or from 5.6V-7.4V when its ground is elevated.)  I need to convert this to a digital signal that is referenced to fixed system ground with a 3.3V pk-pk amplitude.  Will the ISO6720 solve my problem?  It's not clear from the datasheet if there are limits on the absolute voltages of GND0 and GND1, respectively.  Please let me know if my problem is not clear.

  • Hello,

    Thank you for your question. 

    From my understanding, you would like to convert your digital signal from one voltage to a different voltage, where the signal goes from 1.8V domain to 3.3V with a difference in ground being 5.6V-7.4V.

    Yes, the ISO6720 can work for your application

    Our digital isolator devices can be supplied voltages within the recommended operating conditions on both sides of the device. Since the isolation barrier separates the two sides, each side can be sourced independently with any voltage within recommended operating conditions. For more information on having different voltages on either side of a digital isolator, please checkout this FAQ:[FAQ] Can I power the two sides of a digital isolator with different voltages?

    Our digital isolators can also tolerate ground potential differences up to several thousand volts. Since your difference is 5.6-7.4V, the ISO6720 device should work for your application.

    Since the ground potential difference you require is low, I would also recommend our ISO652x family of functional isolators. This family of digital isolators is brand new and introduce functional isolation with lower cost as well. Please feel free to checkout the ISO652x devices here: ISO6521 data sheet, product information and support 

    Regards,
    Aaditya Vittal

  • Thank you so much for the answer and alternative part recommendation! 

  • Aaditya, it looks like the only product in the ISO652x family that is available is the ISO6521REUR which has default high outputs and one channel in each direction.  When will the ISO6520F be available in the VSON package?

  • Hi Matt, 

    Thank you for your question.

    Please give me some additional time to ask my team. I will get back to you as soon as I get a response.

    Regards,
    Aaditya Vittal

  • Hi Matt,

    Thank you for your patience.

    The ISO6520F should be available starting at the second half of this year.  As described on the first page on the datasheet, The information on the ISO6520F is subject to change as it has not been released yet.

    Regards,
    Aaditya Vittal