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OPA548: Does output current limit drift with aging?

Jeff Sasao
Prodigy 10 points
Part Number: OPA548

Using the OPA548 and trying to determine if a set current limit output will drift with aging.  I understand the limit is set via an external resistor and that resistor can drift over time causing the current limit to change.  But does the internal current limit circuity of the op amp have any drift potential with aging?  If it does, is there a chart showing what the expected drift could be over a 25 year period?

  • 0
    TI__Guru 67761 points

    All life tests, including OPA548, are conducted for an equivalent of 10 years (87,600 hours) of constant operation at 25 deg C so any specification above 10 years is not guaranteed. The maximum life-time shift of any parameter expressed as an absolute number, like Ilim, may be up to +/-10% of its maximum specified initial error but most shifts are much lower than that.  Since max/min Ilim is not specified in the datasheet, its maximum Ilim life-time error may be up to 10% greater than the actual error initially measured. The shift may also be approximated by the square-root function of time - see below.

    Having said that, since at 25 deg C most IC’s can last far longer than 10 years, for as long as the part continues to work the long-term shift should continue to follow square-root function equation, which means after 25 year the max shift could be no more than: +/-10%*sq-rt(25/10) = +/-15.8% of actual error initially measured.

    Of course, all of the above considerations do NOT include shift caused by the long-term change of the value of an external resistor, Rcl.