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SN74LVT245B: Pull up resistor for SN74LVT245B?

shanthi s
Intellectual 420 points
Part Number: SN74LVT245B

Hi,

I want to add pull up resistor in the input side for 5volt.

Can you please help me to select a pull up resistor value limit?

Thank you in advance.

  • 0
    Guru 243680 points

    The datasheet mentions a theoretical maximum leakage current of 20 µA, so to prevent the voltage drop over the resistor from becoming too large, it must be less than 85 kΩ. (See Choosing an Appropriate Pull-up/Pull-down Resistor (SLVA485).)

    If the pull-up resistor is only a fallback for when the actual signal source is not present or not yet powered up, then you don't need to go lower. Use a common value like 68 kΩ or 47 kΩ.

    But if you are using an open-drain output to drive the signals, then it might be necessary to use a lower value, depending on what frequency you need to achieve.

  • 0 in reply to Clemens Ladisch
    Intellectual 420 points
    Hi Guru,

    Thanks for the quick response.

    I am not using a high impedance state.

    I have choosed 10Kohm pull up resistor (5v source) at the input side.