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LM331: please recommend a model of the operational amplifier

daohai wang
Prodigy 170 points
Part Number: LM331
Other Parts Discussed in Thread: LM321, LF356, LF411, TL071

LM331 (F to V). In the pdf of Fig. 19, the voltage output portion has an operational amplifier. Can recommend a model and wiring method?

I originally planned to use the LM321 for inverting input. The result failed (voltage is pulled low, output is abnormal). I do not know why.

thx..

  • 0
    Guru 140200 points
    Hi Wang,

    have you noticed that the LM331 in figure 19 of datasheet is powered by a unipolar supply voltage but the OPAmp is powered by a bipolar supply voltage?

    At the time when the datasheet was written the LF411 or LF356 were widely used. See figure 14 of datasheet. So, I would take an unipolar +15V supply voltage for the LM331 and a bipolar +/-15V supply voltage for the OPAmp. For the OPAmp I would take the TL071.

    Kai
  • 0 in reply to kai klaas69
    Prodigy 170 points

    thx.

    but +/- 15V maybe complex with my design.

    so i want 5V supply voltage. Can i use such like OPA320 ??

    Can this OPAmp be powered by a unipolar power supply(+5V)?

    be simple .no complex.

  • 0 in reply to daohai wang
    Guru 140200 points

    Hi Wang,

    you want something simple? Then use the "Simple Frequency-to-Voltage Converter" shown in figure 18 of datasheet. :-)

    You also might want to have a look into this appnote. There you will find some interesting single supply solutions:

    Kai

  • 0 in reply to kai klaas69
    TI__Genius 11135 points
    Wang

    We have not heard back from you so we will close this thread. Please reply if further discussion is needed.

    Thanks
    Dennis