• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 2 answers
  • Subscribers 14 subscribers
  • Views 283 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ISO7842: High-Speed Uni-Directional support bi-directional/I2C-interface feasibility discuss

Neil Chen
Prodigy 120 points

Part Number: ISO7842
Other Parts Discussed in Thread: ISO7742

Hi Sir, 

Current, my project will plan to find bi-directional isolator and support I2C interface, cross review design forum and get this one schematic be reference as picture. 

image.png

It look like can using High-Speed isolator of TI product to easily achieve, but have an one question to asking after review datasheet: 

whatever ISO7742 or ISO7842 chips solution, the feature information mentioned signaling rate can reach to 100M-bps but possibly can up to 1M-bps in low-power mode. 

=> if my design adopted I2C interface which necessary support 100K-/400K-/1M-Hz multi-modes, does this one reference schematic can following to execute? My understand is possible "No", do you agree?! 

image.png

Plz confirm and many tks!

By Neil

  • 0
    TI__Mastermind 21745 points

    Hi Neil,

    Please give us an extra day to review and respond.

    Regards,
    Aaditya

  • 0 in reply to Aaditya V.
    Prodigy 120 points

    Hi Additya, 

    Sure, keep waiting for your update on next coming days. 

    By Neil

  • 0 in reply to Neil Chen
    TI__Mastermind 21745 points

    Hi Neil,

    Thanks for your patience.

    The ISO7772/ISO7842 in an I2C application will have a difference in the signal data rate capability. Since there is a loop back in the circuit design, the data rate would have a certain delay (double the propagation delay) causing there to be a slower data rate.

    Regards,
    Aaditya

  • 0 in reply to Aaditya V.
    Prodigy 120 points

    Hi Adaitya, 

    following your reponse, I think the ISO7742/ISO7842 solution to implement relative I2C application case, the isolator actual data rate level should reply on external circuit to achieve? for example, this one promise the propagation delay specification right? But, the system-level bit rate need check external side to make a final decision. 

    Above my observe, it's right? if have any mis-understand, plz help to explain more details, tks again! 

    Neil

  • 0 in reply to Neil Chen
    TI__Mastermind 21745 points

    Hi Neil,

    Neil Chen said:
    the isolator actual data rate level should reply on external circuit to achieve?

    Yes, but this depends. Since the I2C external circuit setup involved 2 channels in which the signal is looped back. When this loop back occurs, the propagation delay is technically doubled causing the over data rate to be reduced. 

    Neil Chen said:
    But, the system-level bit rate need check external side to make a final decision. 

    Yes, your understanding here is correct. the system level data rate would be helpful in understanding how much data rate you need. Since the digital isolator data rate is relatively high, the slight reduction of this due to the loop back signal may be less of a concern if the system-level data rate is low.

    Regards,
    Aaditya