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LM258: LM258 To be 20mA output

Alex Chen9
Expert 1075 points
Other Parts Discussed in Thread: LM258

HI Sir

I use the LM258 to be a 4-20mA Output, I find the output current from 20mA down to 19.985mA, it's out of spec,

do you have any suggestion? thanks

  • 0
    TI__Guru**** 157036 points
    Alex,

    Are you saying the current should be 20.000mA but is 19.985mA? That is a 0.075% error which is nothing. I'm impressed that it is that close.
    Perhaps, I am missing your point. I'll look at it again on Monday (US time).
  • 0
    Guru 140200 points
    Hi Alex,

    the deviation is less than 0.08% of full scale. Is this a problem?

    Kai
  • 0 in reply to kai klaas69
    TI__Guru**** 157036 points
    Alex,

    I took a second look like I said. The current can vary +/-100uA just from the +/-5mV input offset error range of the LM258 at 25C. More at potential input offset at temperature extremes . The accuracy of the resistors can also change the current.