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ISOW7841: Isolation of DAC and ADC for medical devices

Benyuan Liu
Intellectual 595 points
Part Number: ISOW7841
Other Parts Discussed in Thread: ADS9120, DAC3171, ISO7841, MUX36S16

Hi, I want to design an IEC 60601 compatible isolation solution for a medical device. This device requires generating

  • 0
    Intellectual 595 points
    (I do not know why the full content can not be displayed, so I post them below)

    Hi, I want to design an IEC 60601 compatible isolation solution for a medical device. This device requires generating <2MHz waveform using DAC (DAC3171) and sample using 2 16bit ADC (ADS9120). However, the pin count needed to be isolated is around 40 pins and the power on the analog side is around 1W. Can I use ISO7841 or multiple ISO784x to do the Isolation ? and how could I design the powering circuit for DAC and ADC that meets the needs of IEC 60601?

    Thanks!
  • 0 in reply to Benyuan Liu
    TI__Intellectual 2900 points
    Hi,

    Both ISO784x (Reinforced Digital Isolator) and ISOW784x (Reinforced Digital Isolator with Integrated Power) are IEC 60601 End equipment standard approved.
    From your query it looks like the system has 40 channels which need to be isolated is that correct? Could you please confirm?
    Multiple ISO784x devices can be used in parallel to isolate all the required channels.

    Regards,
    Anand Reghunathan
  • 0 in reply to Anand Reghunathan
    Intellectual 595 points
    Thanks for your reply!

    Yes, DAC3171 has approximately 20 pins to be isolated, two ADS9120 have 10 pins to be isolated, two MUX36S16 have 12 pins to be isolated.

    The channels (20 + 10 + 12 = 42) to be isolated is a little bit too much (isn't it?), this is what I am concerned that ISOW784x and ISO784x can be used in this applications ? It may take too much board area.

    Besides the large amount of channels to be isolated, the power consumption on the Isolated side is another concern. DAC3171, ADS9120, and multiple (around 24) Op-Amps, Can these devices be powered using ISOW784x?

    I calculated the power required on the Isolated side, it is around 700mW totally. With a budget of 80%, the conservative power consumption may be ~1W. What make it worse is that, the power rails on the isolated side includes +-5V, +-12V, 3.3V and 1.8VA, which can only be generated from the output of ISOW784x and require multiple LDOs, consequently consumes more power.

    liu.
  • 0 in reply to Benyuan Liu
    TI__Intellectual 2900 points

    Hi Liu,

    A small correction to my previous reply. ISO784x is approved for IEC60601 and ISOW784x is going through the certification process and should be done in another 4 to 5 months.

    Can you please share your email ID?
    I can discuss over email with you to understand the system better and suggest the best fitting solution.

    Regards,
    Anand Reghunathan

  • 0 in reply to Anand Reghunathan
    TI__Intellectual 2900 points
    This thread has been closed over email.

    Regards,
    Anand Reghunathan