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74LVC1G123

Sam Guo
Intellectual 380 points

 

Tolerance of 74LVC1G123DCTR

 

If I tune the RC values for 74LVC1G123DCTR one-shot to get a pulse of 400ns, I want to know the variance of the time if I install 10,000 pieces of 74LVC1G123DCTR chips on the same board. The acceptable value is between 380ns and 420ns. Does anyone know the timing error range for this one-shot?

 

Sam

  • 0
    Guru 243110 points

    Designing with the SN74LVC‍1G123 Monostable Multivibrator (SLVA720) says that the pulse length depends on the temperature and supply voltage, but the largest variations come from the tolerances of your R/C.

    It appears there are no numbers for the accuracy of the internal 0.63212 × VCC voltage threshold.

  • 0 in reply to Clemens Ladisch
    TI__Guru* 96591 points
    Hi Sam,
    In my tests, I have seen less than 1% variance from our device over temperature - when I exclude the resistor and capacitor from the test chamber. Unfortunately, I do not have test data across all possible process/voltage/temperature variations, so I cannot guarantee this for all situations.

    We typically tell people to only use these devices in situations where they need an approximate delay - for example when you want to reset a processor for "a few microseconds" an MMV is a good solution, or when a delay needs to be "at least" some value.

    In theory, if you can get great capacitors/resistors for the external timing circuit, then this part could maintain the timing you want. I would probably recommend going with a more precise technique for your application.