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TXS0102: I2C signal can't turn low

Hardy Xue
Expert 3640 points
Part Number: TXS0102

Hi Team,

Customer use the TXS0102 for I2C bus communication between 3.3V to 1.8 V but they find out the output of 1.8 can’t turn low. After they had added Rpd around 100K ohm, the output seems is normal. Customer want to know the theory why output of TXS0102 needs to be added Rpd to decrease VOH/VOL?

Best regards,

Hardy

  • 0
    TI__Guru* 97046 points

    Hi Hardy,

    The TXS0102 has been used in many thousands of I2C applications without any problems, so I'm not sure why you're running into issues. To explain the theory behind the issue, I would need a circuit to analyze.

    Can you provide a full schematic, including any external or internal pull-up/pull-down resistors used and details regarding the drivers on each device (ie I_OL and V_OL spec -- or a part number & datasheet)?

  • 0 in reply to Emrys Maier
    TI__Expert 3640 points

    Hi Emrys,

    Sorry for late replay.

    Unfortunately, customer cannot provide schematic. Or could you simply explain why output of TXS0102 needs to be added Rpd to decrease VOH/VOL?

    I see that there is defined VOH and VOL value on datasheet. 

    Best regards,

    Hardy

  • 0 in reply to Hardy Xue
    TI__Guru* 97046 points

    Hi Hardy,
    It doesn't need a pull-down resistor to reduce the VOH and VOL, but adding a pull-down resistor will reduce VOH and VOL. The statement in the datasheet is a caution against doing that.