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ISO7763: ISO7763 Reduce Propagation Delay Time

Blindu Marcel
Intellectual 280 points
Part Number: ISO7763
Other Parts Discussed in Thread: ISO7631FM, ISO7640FM, ISO7641FM

Hi all,

We design system with 4 ADC AD7768-1 and with the ISO7763 digital isolator for SPI.

And we have realized that with 15MHz SPI frequency the microcontroller does not interpret the data (MISO) correctly due to the "Propagation delay time".

Any other digital isolators that have less propagation delay time or other technique to reduce this time in order to be able to increase the SPI clock?

Best regards

  • 0
    TI__Genius 14410 points

    Hello,

    Thank you for your question. Is 6 channels a requirement for your system? The ISO7763 has the lowest propagation delay of our 6 channel digital isolators. If 6 channels is not a hard requirement, the ISO7631FM, ISO7640FM, or ISO7641FM may be good options with lower propagation delays of 7ns (typical). However, please note that these are older devices with lower isolation ratings so please make sure to verify what level of isolation is required for your system before moving to an alternative part.

    Delays from cables and other devices in the system can also impact the achievable SPI speeds. Possible solutions, in addition to the isolator propagation speed, is using devices that read data on both the falling and rising edges of the clock as well as looping the clock back to the MCU so the MCU is able to quantify and compensate for the round trip delay.

    Regards,
    Darrah