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LM339: Pullup Resistor Design Method of LM339

Part Number: LM339

Tool/software:

Hi Team,

Customer is ask for the pullup resistor design method of LM339, I find below spec in the datasheet, could you please help me further understand how to use the IO, IOH-LKG, IOL? And what's the test condition meaning of IOL, what's the VOL and VID means? Thanks a lot!

BRs,

Francis

  • Hello Francis,

    Please see section 6 and 6.2 of the LM339 family application note:

     Application Design Guidelines for LM339, LM393, TL331 Family Comparators

    VID is the input differential drive voltage - so -1V is applied between the inputs to force the output low (output transistor conducting).

    The output is forced low and sinking 4mA, and the resulting voltage across the low output is VOL (the "Y" axis in the following graph):

    The more current sunk (IOL), the greater the voltage across the output (VOL).

    IOL-LKG is how much current is "leaking" when the output is high (not conducting). So there can be a few nA flowing to GND when the output is high. Normally you do not need to worry about this current, except if you use very high value (>10M) pull-up resistors.