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LM311: lm311 circuit consulting

TTG tt
Prodigy 160 points
Part Number: LM311
Other Parts Discussed in Thread: TL331, TL331B, TLV1701

Dear team, my circuit is as follows. The circuit input is normal. The power supply is normal. The circuit has no signal output.。

The input pulse signal is about 200mv. Comparison setting is about 160mV。

  • 0
    Guru 140200 points

    Hi TTG,

    the input and output pins of EL816 opto are swapped. And the output terminal of circuit sits at the wrong place. Have a look into the datasheet of EL816.

    Kai

  • 0 in reply to kai klaas69
    TI__Mastermind 24520 points

    Thanks Kai, good catch.  

    We will hold the post open for a while while the customer corrects the circuit configuration.

    Chuck

  • 0 in reply to kai klaas69
    TI__Guru 53846 points

    Hello TTG,

    Agreed about the opto-isolator. You need to "flip horizontally", and the "ValueAct" output needs to come off pin 1 of the isolator, not GND.

    However, you are violating the LM311 input voltage range as it is NOT a ground-sensing device.

    The valid input range for your circuit is +0.5V to +22.8V. Your maximum input voltage is 0 to 0.2V. While it may "seem" to work now, you will run into issues over temperature and possibly across lots.

    I would recommend the TL331, TL331B or TLV1701, though they are slightly slower. If you can run off a lower supply voltage (<5V), then there are more options.