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LMH1218: Internal pull-up and pull-down values ​​for 4-level input configuration pins

Hayato Akuzawa
Prodigy 60 points
Part Number: LMH1218
Other Parts Discussed in Thread: LMH1219, LMH1219EVM

Tool/software:

Hello.
What are the internal pull-up and pull-down values and accuracies for the 4-level input configuration pins of the LMH1218?
Are they 30kΩ pull-ups and 60kΩ pull-downs as in the LMH1219?

  • 0
    TI__Genius 9209 points

    Hi Hayato-San,

    As is stated in the LMH1219EVM user's guide, the LMH1219 has the above 4-level input configuration, The configuration pins are set up the same way for the LMH1218.

    Best,

    Nick

  • 0 in reply to Nick Peabody
    Prodigy 60 points

    Hi Nick-san,

    Thank you for your reply.

    But, I would like to know the internal pull-up and pull-down values and accuracy of the 4-level input configuration pins.


    Background on this question.
    Our organization has placed restrictions on the resistor values that can be used on the board.
    This is to reduce the number of component types and reduce costs.
    Currently our available values are 1k, 10k, and 22kΩ.


    The level R setting is a 20kΩ pull-down, but I would like to consider whether the level R requirement can be met with 22kΩ instead of 10kΩ+10kΩ=20kΩ.
    (To make one pull down resistor).
    So I want to know the internal pull up and pull down resistor values and accuracy.

    Thanks,

  • +1 in reply to Hayato Akuzawa
    TI__Genius 9209 points

    Hi Hayato-San,

    I confirmed that the value for the pullup is 30k and the value of the pulldown is 60k ohms.

    Based on this information, we can determine if the 22kΩ resistor would be acceptable.

    Say we have a 2.5V power supply. This means that the threshold between 0 and R would be 0.5 V and the threshold between R and F would be 1.25 V. As long as we fall between these two voltages, then the pin level will be R. When adding a 20 kΩ to ground, we can determine the voltage at the output based on adding a resistor in parallel with the 60 kΩ pull-down resistor, and this would give 0.83 V at the output.

    By the same calculation with a 22 kΩ resistor, the voltage would be approximately 0.87 V. This voltage falls well within the threshold for the R level, and therefore would be acceptable.

    Best Regards,

    Nick