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LM2904: LM2904 max output current

Vladimir Naumenkov
Expert 2970 points
Part Number: LM2904
Other Parts Discussed in Thread: TLV9002,

I'd like to use LM2904D with linear optocoupler. Please, see my circuit in attach. I need 12 mA output  current (marked "IF" on the circuit)  , temperature from minus 40 to plus 50 C. Can I set 12 mA output current for LM2904D?

TIA

Sincerely,

Vladimir Naumenkov

www.agat.by  

LOC series AN-107.pdf3580.LM2904D circuit.docx

  • 0
    Guru 140200 points

    Hi Vladimir,

    you might also want to have a look at this appnote:

    appnote50.pdf

    Kai

  • 0 in reply to kai klaas69
    Expert 2970 points
    Dear Kai, thank you
    Generally speaking, the circuit using LM2904D and LOC110 works quite well for me too - I have already tested it. Just doubt the output current of LM2904D. I would not want to use an expensive amplifier.
  • 0 in reply to Vladimir Naumenkov
    TI__Mastermind 30600 points
    A newer (and also cheap) op-amp that you could look at is the TLV9002. It will support 12mA output current and doesn't have some of the other quirks that come with using the LM2904. The LM2904 can provide 12mA output current but you will also take a significant hit on the output swing.

    Best,
    Paul
  • 0 in reply to Paul Goedeke
    Expert 2970 points

    Dear Paul, thank you
    Please, report, what max output current I can use for LM2904D in this application? No more than 10 mA? Or do you still not recommend to apply LM2904D here?  I use DC signal only. To be honest, I always thought, that LM2904 is very good amplifier!  But, apparently, I'm outdated with LM2904 !

  • 0 in reply to Vladimir Naumenkov
    Guru 140200 points
    Hi Vladimir,

    the LM2904 IS a very good OPAmp, but it's a dino...

    According to figure 8 of datasheet the maximum output voltage at 10mA source current is 3.5V typically, when using a supply voltage of 5V.

    Kai
  • 0 in reply to kai klaas69
    TI__Mastermind 30600 points
    Hi Vladimir,

    The LM2904 will be able to provide 12mA output current, but you will have to see if the output swing limitation is too much for your application and there may be some concerns over temperature as well.

    From your schematic, it looks like you're sourcing current, which is the better direction to have the LM2904 provide current. The sink characteristic is a little worse. I would also recommend that you take a look at this app note which describes some of the quirks of this part:
    www.ti.com/.../getliterature.tsp

    Best,
    Paul
  • 0 in reply to Paul Goedeke
    Expert 2970 points

    Dear Paul,
    Dear Kai!
    Thank you.

    Output voltage of LM2904D will be no more than 3V in my case. The output current will be no more than 10 mA.

    Sincerely,
    Vladimir Naumenkov
    www.agat.by