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TXS0104E: Drive capability of Port B

Lindsey Fike
Intellectual 2200 points
Part Number: TXS0104E
Other Parts Discussed in Thread: SN74LVC06A, SN74LVC3G06

A customer has TXS0104ERGYR on their board, and they have a couple of LED’s on it’s port B, which is powered by 3.3V.

If a Port B output pin is high, what is the drive capability of that pin (when operating at 3.3V)?

I do note that TX0104ERGYR datasheet shows an absolute max continuous current of 50mA, but I don’t see a typical operating max current spec’d out.  (And I’m not sure if chip is designed to last with a continuous load of say 10mA or not.)

  • 0
    TI__Mastermind 43480 points

    Hey Lindsey,

    This device provides no drive of its own and won't be able to drive LEDs. The only DC drive is provided by the internal pull-up:

    I recommend using a buffer for this. Are they shifting up from a lower voltage?

  • +1
    Guru 259890 points

    As with many other logic devices, the current is specified in the test condition for VOH; it's 20 µA.

    If possible, change the board so that the LEDs are driven by the cathode, i.e., switched to ground. Please note that the TXS is a passive switch; the low-level drive strength at the B output is that of the device that is driving the A input. If the device on the A side does not have enough drive strength, replace the TXS with a buffer with overvoltage-tolerant open-drain outputs, e.g., SN74LVC3G06, SN74LVC06A, or similar.