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LM2917-N: Design rules for a F/V converter

Andreas Rothe91
Prodigy 20 points
Part Number: LM2917-N


THIMC,

I want to convert a PWM signal (14Vpp  dc, duty Cycle 50%, 4kHz to 8kHz) into a PLC conform Signal 0-10V with the above mentioned F/V converter LM2917-N.

What are the resistor and Cap  values? Maybe an OPAmp for the output to amplify my Voltage ?

Your help is very much appreciated.

Regards

Andreas Rothe

  • 0
    TI__Guru* 93105 points

    Hello Andreas,

    Take a look at the AN-162 applications note. It has quite a bit of information about how to go about selecting the R and C values for the LM2907/LM2917. You will need to know what supply level you intend to power the tachometer with, how much ripple can be tolerated on the F/V output voltage, and a few other operating needs.

    If you still need assistance after reviewing the application note, let me know.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0 in reply to Thomas Kuehl
    Prodigy 20 points
    Mahlzeit!


    Hi Thomas,

    yes I did read the pdf and no I havent any clue whats going on in there.

    I have the power supply 24Vdc ( hope thats not too much for the LM2917) and I have the power to the tachometer as follows:

    14Vpp dc, duty Cycle 50%, 4kHz to 8kHz.

    I need a PLC conform output of 0-10V.

    Problem is that the PLC only got 1 high speed counter and I need 3. So I added an analogue input card.

    Regards

    Andy
  • 0 in reply to Andreas Rothe91
    TI__Guru* 93105 points

    Hello Andreas,

    The LM2917 can be applied with a 24 V supply. The absolute maximum supply rating is 28 V.

    Have you determined what pulse width you intend to etablish for the tachometer circuit?

    Regards, Thomas

    Precision Amplifiers Applications Engineering