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TXS0108E: VCCA/VCCB/OE Question

Jerry Chu
Genius 4915 points
Part Number: TXS0108E

Hi Expert,

I connected VCCA and OE to 3.3V, connected VCCB to 5V. But in my application, the 3.3V will ramp up first. If necessary, the 5V will be ramp up by option.

The datasheet didn't recommend it. But datasheet first page also shows "No Power-Supply Sequencing Required – Either VCCA or VCCB Can Be Ramped First".

Do you think any risk for my application? Thanks!

BTW, the data direction is from 3.3V to 5V only.

  • 0
    TI__Guru* 97046 points
    Hi Jerry,
    Controlling the device as you described won't hurt the TXS0108E at all, but it could produce unexpected outputs because the I/Os are turned on with nothing driving the B-side control circuitry.

    I would recommend holding the OE pin LOW until the 5V supply is connected and stable. One method to do this would be to connect a 100kohm resistor from OE to ground, then short OE to VCCB. Note that the maximum input voltage on the OE pin is 5.5V according to the Recommended Operating Conditions table.