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LMC555: Expected accuracy at longer time intervals

ReedKacz
Expert 3687 points

Part Number: LMC555

Hello,

I have a customer wanting to use a LMC555CMM/NOPB in order to have a one-shot timer with length no shorter than 8.13 seconds.

The datasheet specifies the LMC555 timer accuracy at only one set point (5V, 1.1ms set - 1.0ms min and 1.2ms max).

What can the timing accuracy be expected to be at lets say 8.66 second set point? 

Thanks,

Reed

  • 0
    TI__Guru**** 174826 points

    Reed,

    The accuracy will extrapolate to longer time. At longer time period the need to maintain supply voltage over the timing period becomes more significant. In the end, the main variance and drift will be the capacitor's capacitance.  For 8.13 seconds minimum, bump out the typical to longer time provided there is no maximum.

    With 8.66 seconds and assuming timer is only variable, expect less than +/-9%, 7.88s to 9.44s ; although that spec is pessimistic.