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CD40106B: Regarding adjustable threshold voltage of CD40106B

Part Number: CD40106B
Other Parts Discussed in Thread: LM339

hello,

In the datasheet, i am not able to find out whether the threshold voltage ( VT+ and VT-) of IC CD40106B are adjustable or not. If yes, then please let me know how could i do that. If no, will you please suggest me another Hex Schmitt trigger IC (either inverting or non-inverting) with adjustable threshold voltages.

Thanks

  • Hello,
    Schmitt-trigger buffers do not have adjustable threshold voltages -- ever. At least, I have never seen one that does, and I've been TI's logic expert for about 4 years now.

    In order to change the thresholds, you would have to use a comparator and design the feedback circuit yourself. If you are interested in taking that route, I would recommend opening a new post with a comparator part number (for example, LM339) so the comparator team is notified; I'm sure they could help you out with the correct circuit.
  • Thankyou for this clarification. One more thing that i would like to ask, can i use the same IC to obtain a glitch free output? The glitch peak to peak voltage is around 10V
  • Regardless of the supply voltage, a "glitch" at the input of 10V will switch the output. The minimum hysteresis of the CD40106B (operating at 15-V supply) is 1.6 V. This value is the maximum noise value that will be suppressed by the Schmitt-trigger input. Any input variation larger than 1.6V could cause a "glitch"

    If your input "glitch" lasts for 1ps, the device won't have time to switch at all and it won't make a difference.

    If you were to provide some details I could give a better answer....
  • Hi Ishank,

    can you specify your regular signal? Is it the "glitch", or is the "glitch" noise which you want to suppress?

    Kai
  • Hello sir,

    The voltage level of the input signal comming from the external world is around 12V peak to peak of pulse width 10usec. Yes,  these glitches are the noise signal in the input having a voltage level up to 10V which I want to suppress so that the output level will not change.  Please tell me the way to overcome this problem.

    Thanku

  • Hi Ishank,

    not knowing more about your application, I would recommend to introduce some low pass filtering to filter out these nasty glitches.

    What is your regular signal (amplitude, frequency, waveform, etc.)? Can you show a scope plot of your regular sgnal and the glitch?

    Kai