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Original question:

LM10: Technical issues

LM10: Reference Output and Reference Feedback connections

Walter Cromer
Intellectual 255 points
Part Number: LM10

I have a similar question about the reference pins.  I am using the LM10CN/NOPB as a unity gain buffer amplifier between a high-impedance output sensor and our scope and lab DA system, which have an identical input impedance to our sensor.   This has worked very well until recently and now we are seeing some weird stuff with the system and I'm wondering if there may be some problems with the buffer amp circuit.   I am only using the op amp with inputs on pins and 2&3 and output on 6.  Vcc on 7 is 1.8V and pin 4, V- is at ground.

I've not connected any of the other pins to anything.  Should I?  Will Reference Output and Reference Feedback affect op amp "#1"?

Thanks!

WC

  • 0
    TI__Guru**** 152966 points

    Hello WC,

    LM10 is not high impedance input compared to modern op amps. LM10 input current is about -10nA. The unused reference feedback should float high, so reference output should be low. It would be best to connect pins 1 & 8 together, but it doesn't seem to be required. It don't expect reference section to affect the op amp.

  • 0 in reply to Ron Michallick
    Intellectual 255 points

    Thanks for your help!  I've used the LM10 so long without any issues that I didn't even look for ones with higher input impedance!   I'll be sure to review that before I make the next revision of this prototype.

    Walter