LM2907/LM2917 - Maximum Frequency supported

Discussion in 'General Electronics Chat' started by deepika.r, Feb 4, 2016.

  1. deepika.r

    Thread Starter New Member

    Feb 2, 2016
    2
    0
    1. I have been trying to find out the maximum frequency LM2907/LM2917 can support. The datasheet does not mention the threshold but has been tested for linearity upto 10khz. Need to know if the IC supports upto 15khz.
    2. There is also an application for 'Changing Tachometer Gain Curve'. Any idea on how the slope can be shifted to measure frequency upto 15khz
    3. If any Simulation model is available, that would be helpful. the LTspice models already posted in this forum does not run simulation, supporting file missing.

    Thanks,
     
  2. Veracohr

    Well-Known Member

    Jan 3, 2011
    552
    76
    Equation 4 under "Applications Information".
     
  3. Bordodynov

    Active Member

    May 20, 2015
    643
    188
    You havean artificial problem.It is ridiculous to think that chip transistors operate up to 10kHz. Reduce capacity.Proportionally reducedoutput voltage.
    Datasheet --> Easy to Use; VOUT = fIN × VCC × R1 × C1
     
  4. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,508
    380
    hi deep,
    Unzip and try this zip file for 2907/2917, they do work OK.
    E
     
    deepika.r likes this.
  5. deepika.r

    Thread Starter New Member

    Feb 2, 2016
    2
    0
    Are you saying they cannot work greater than 10KHz?
    If they can, what is the the linearity error and the threshold of R1, C1 and C2, so it works satisfactorily? Datasheet says upto 10KHz error is 1% max.
     
  6. bertus

    Administrator

    Apr 5, 2008
    15,652
    2,348
    Hello,

    The datasheet tells you that C1 can have a minimum value of 500 pF.

    Bertus
     
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