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P82B96: General question - I2C as a local bus to expand IOs by using the I2C buffer

Ernest Yong
Expert 4315 points
Part Number: P82B96

Tool/software:

Hi Team,

My customers are trying to use I2C as a local bus to expand IOs by using the I2C buffer to boost the range (up to 3m) and improve the noise suppression.

These modules being part of their security system will be used in the relatively noisy environment in a metal enclosure,

This solution’s benefit is making the expansion module MCUless to reduce the firmware development effort and easy for production. how do you think of this solution?

Appreciate your opinion and suggestion for the best approach.

Best Regards,

Ernest

  • 0
    Guru 271610 points

    I²C was designed for on-board communication; single-ended signals are not very noise resistant.

    The P82B96 allows to use more current one the T/R lines, which might help. But if the environment is too noisey, you would need robustness by using a differential protocol like LVDS or RS-422; you'd have to add such transceivers behind the P82B96.

  • 0
    TI__Mastermind 29123 points

    Hi Ernest,

    Clemens brought up some good points about the P82B96. 

    The bus extender was meant to do just that for the I2C protocol, but does not do too well with noisy environments. 

    CAN/RS422/RS485 etc. or any differential protocol would be more suitable for this type of environment. 

    If the customer is looking for simple bus extension because of the current drive of the P82B96, then this would be the device to use, up to 4000pF drive on the buffered side. 

    Regards,

    Tyler