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ISO1540-Q1: SMBus and I2C Application

Part Number: ISO1540-Q1
Other Parts Discussed in Thread: TCA9517A, ISO1541, ISO1540, BQ40Z50

Hello Support team:

I met SMBus programming issue cause by noise or longer communication line.

Project diagram as below;

1. The host system(MCU) SMBus + ISO1540Q1/ISO1541Q1 + the programming MCU (SMBus). Is it good solution for avoid noisy? 

2. The host system(MCU) SMBus +TCA9517A (level shift)+ ISO1540Q1/ISO1541Q1 + the programming MCU (SMBus). 

Which solution is good?

I think the item 1 is good?  item 2 TCA9517A not good?

  • Hi Mike,

    Thank you for reaching us for suggestion to improve noise performance of the system.
    If the issue caused is due to common-mode noise due to longer communication cable on I2C bus then yes, using ISO1540/ISO1541 would help you eliminate the noise and support higher error free communication range.

    For noise improvement, both options should work equally the same. The level translator is needed only if host MCU logic thresholds are not compatible with ISO154x logic thresholds otherwise, the level translator is not required.

    Please do share both MCU part numbers so that I can check if there is any issue in interfacing them directly to ISO154x. Thank you.

    Koteshwar Rao
  • Hello Koteshwar:

    Thank you for your support quickly!

    The host MCU is TI MSP430 5501;

    Slave MCU is BQ40z50.

  • Hi Mike,

    I looked at the datasheet of both devices, you do not need any level translator and can interface ISO1540/ISO1541 directly to both the devices. Thank you.

    Koteshwar Rao
  • Yes, Sir!

    You’re right!

    It’s match my application project and view point.

    I greatly appreciate your great support!

    If met any other questions, I will notice to you on the first time.

    See you E2E forum later.

    Thanks again!