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Original question:

TXS0108E: TXS0108E

TXS0108E: TXS0108E

Rajan Bedi
Expert 1595 points

Part Number: TXS0108E

Tool/software:

Adding an external 1K resistor to the B side raises VOH from 2.5V to 3V3 which is good, however, increases VOH from 20 mV to 0.71V, but the max. VIH is 0.5V: can you recommend another value of external-pull that will provide slightly less voltage increase please

Thank you

  • 0
    Expert 1595 points

    I have discovered the following:

    external 1k pull-up, VOH = 3.1V and VOL = 0.7V

    external 4.32k pull-up, VOH = 2.8V and VOL = 0.2V

    external 2.67k pull-up, VOH = 2.9V and VOL = 0.3V

  • 0
    TI__Mastermind 49091 points

    Hi Rajan,

    The observations you are seeing is in-line to the characteristics of the device. The use of the external pullups will help with VOH, but will cause VOL levels to shift up due to increase current sink back into driver side.

    Assuming A side driving into B side: VOL = VIL + IOL x RON, or in this case VOLB= VILA+ Ron x (VCCB/ (Rpu // Rpu,ext)).

    Note that the acceptable pullup sizing is dependent on the VIL/VIH of your devices at the I/Os interfaced with the TXS0108E.

    Regards, Jack