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ISO1541

mario soccini
Intellectual 730 points
Other Parts Discussed in Thread: ISO1541

Hi.

I want to build a multidrop i2c isolated bus using ISO1541.

I have a micro master  and 8 micro slave.

I need to do a Read/Write operation.

Is the schematic in attached correct ?

What about speed if the maximum distance is  1 meter ?

Thanks.

Mario.

  • 0
    TI__Guru 55815 points
    Hi Mario,

    Could you please also share us pull-up resistor and VCC1 / VCC2 values? Speed depends on many factors including and not limited to cable type / quality, bus capacitance, pull-up resistor value & error recovery protocol used. With a bus capacitance of less than 400pF and pull-up of 2.2kΩ or less, 100kbps is generally achievable over 1m distance.

    Regards,
    Koteshwar Rao
  • 0 in reply to Koteshwar Rao
    Intellectual 730 points

    Thank you Rao.

    I still haven't chosen the value resistor.Before i wanted to know if the schematic (new) is correct.

    Vcc1=3.3V Vcc2=5V Vcc3=5V.  2.2K on Vcc2 side can be ok ?

    Maybe the problem could be the cable (20cm) between the board master and the board slave (8 circuit in the same board).

    However i can lower the speed... (about 38400).

    Regards.

    Mario.

  • 0 in reply to mario soccini
    TI__Guru 55815 points

    Hi Mario,

    You will need to add pull-up resistors on side 2 of slaves as well, as shown in Figure 25 of datasheet. Otherwise everything else looks fine.

    Best Regards,

    Koteshwar Rao