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TPS23861EVM-612: function of sn74lvc1g07dckt on EVM board

Part Number: TPS23861EVM-612
Other Parts Discussed in Thread: ISO1540

What is the function of sn74lvc1g07dckt  for this configuration on TPS23861EVM-612. What will happen if I directly connect SDA and SDAO? If I don't use a isolation on i2c bus, is it still needed? BTW, this picture is from TPS23861EVM-612 official schematic.

  • Hi Andrew,

    Isolation is not a hard requirement for I2C to work and you can drive the I2C lines directly; however, for safety of the host (laptop for example) from getting damaged, it is recommended to use isolation.

    The digital isolator used is not an open drain output. So the rails may fight each other if you directly connect the outputs together, therefore a open drain buffer is used to pull down on the SDA line.

    For this type of configuration SDAO and SDAI cannot be connected together and must follow what is used on the EVM. If it's desired to connector SDAI and SDAO together, you should use a bidirectional I2C isolator like ISO1540.

    https://www.ti.com/product/ISO1540