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SN74LXC1T45-Q1: Data Pin Pull Down

Lucas Wolter
Genius 17545 points
Part Number: SN74LXC1T45-Q1
Other Parts Discussed in Thread: AVCLVCDIRCNTRL-EVM,

Hi,

In my current design I have a 3.3V source connected to VCCA and a voltage divider network connected to A that's roughly 3.3V. What is the pull down resistance on pin A during operation?

In the datasheet I see in section 8.3.1 that the worst case resistance is calculated with max input voltage and max input leakage current, so from here I calculated it should be 3.25MOhm. But I also saw in section 8.3.1.1 that the I/O pins have a 100k pull down during disabling. Does pin A still have this 100k PD during operation, or does it change to 3.25MOhm? Will I need to consider this internal pull down when calculating resistor values for my voltage divider?

Additionally, can the SN74LXC1T45-Q1 be used with AVCLVCDIRCNTRL-EVM board?

Best,

Lucas

  • +1
    TI__Expert 7900 points

    Hello Lucas,

    The 100kΩ is only on for a short period during disabling and not when the device is operating normally. You are correct in saying the worse case resistance is 3.25MΩ however if you are using pull-ups we suggest not going above 15kΩ.

    Yes, LXC1T45 can be used with the AVCLVCDIRCNTRL-EVM but only with the DCK package.

    Regards,

    Josh