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SN74LXC2T45: SN74LXC2T45

Chandran Panthalanickal
Prodigy 190 points
Part Number: SN74LXC2T45

We are using SN74LXC2T45.

I use only 1A and 1B 

Should I use pull down OR pull up resistor at 2A and 2B. If required, what is the recommended value ?

  • 0
    Guru 298660 points

    2A/B should be pulled down or grounded; see section 8.3.1.1 of the datasheet.

  • 0 in reply to Clemens Ladisch
    Prodigy 190 points

    I use 1A and 1 B for transmitting A to B.

    So, I permanently connect Dir(pin 5) to 5V using 5K resistor.

    In this case, I will connect 10k from 2A(pin 3) to Ground. Is this sufficient ? OR should I pull down 2B also. I believe that need not pull down 2B since it is always O/P. Please confirm.

    If I use 1A and 1B as receiver and transmitter by Dir control, then I need to pull down both 2A and 2B to ground. Please confirm

  • 0 in reply to Chandran Panthalanickal
    Guru 298660 points

    Inputs must not float, and the input buffers on both sides are always active. But an active output forces the input high or low. So pins that always are outputs indeed do not need a pull-down.