• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 18 subscribers
  • Views 554 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Compiler/SN74HC14: SN74HC14

user6418993
Prodigy 10 points
Part Number: SN74HC14

Tool/software: TI C/C++ Compiler

Model :SN74HC14D, brand: TI, used for non-gate oscillator and liquid level detection on the luminescent chemical immunoanalyzer produced by our company, but the detection was not accurate recently. Internal electrical engineer preliminary analysis showed that the input capacitance of this chip exceeded 10pF.
Please assist in arranging analysis.Thank you!

  • 0
    TI__Guru* 96681 points

    Hello,

    Semiconductor devices vary from lot to lot due to process shifts in manufacturing, which is why our datasheets list minimum and maximum values rather than absolute values.

    In this case, the thresholds and input capacitance of the device will affect the oscillation frequency -- this is normal. If you want to maintain consistency in measurement, you would need two identical circuits built on the same board, one with the sensor attached and one without.  Comparing these two frequencies would give you the best results as it would take into account variations in the inverter.