Terminating an unused op-amp

Discussion in 'General Electronics Chat' started by TechnicaliTee, Oct 29, 2014.

  1. TechnicaliTee

    Thread Starter New Member

    Oct 18, 2013
    5
    0
    When using one of the two op-amps in a dual op-amp DIP (TLV2372), which is the best way to terminate inputs & output? Inputs tied together and then to GND or Vdd, and what of the output, tie that to GND or Vdd?
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Tie the two unused inputs to Vss (likely the most negative voltage), and let the output float.
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,797
    1,103
    Don't tie the output to GND or Vdd. That could cause excessive current flow.
    You could tie the output to the inverting input, and tie the non-inverting input to either rail. One rail might be better than the other in terms of standby current, depending on opamp topology (I haven't checked the TLV2372 spec).
     
  4. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,804
    832
    I tie the non-inverting to the center of a voltage divider consisting of two 100k resistors between the rails on an OP amp powered by a single sided supply. This was recommended practices on the LT datasheet.
     
  5. Lundwall_Paul

    Member

    Oct 18, 2011
    220
    19
    Just use pull down resistors on both in/out
     
  6. crutschow

    Expert

    Mar 14, 2008
    13,006
    3,232
    I would tie the output to the inverting input and ground the non-inverting input. That way the amp output isn't saturated, which could conceivably have some adverse effect on the other amp, and it requires no added parts.
     
  7. Lestraveled

    Well-Known Member

    May 19, 2014
    1,957
    1,215
    I agree with crutschow. Configure it as a voltage follower and ground the + input.
     
  8. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,804
    832
  9. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    After reading the TI app note referenced by djs, the advice should read: wire it as a voltage follower with inverting input tied to output, tie the non-inverting input to a (bypassed) dc voltage source greater than Vss and less than Vdd which is within the Common-Mode Range.
     
  10. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,031
    3,802
  11. TechnicaliTee

    Thread Starter New Member

    Oct 18, 2013
    5
    0
    Yes, I could have Googled (I did a little) and looked-up details but having dialog with all of you is much more fun. Thanks for all the helpful feedback (no pun intended). You're all terrific! I'm looking forward to our next exchange. Now it's time to go play with a cranky Agilent B1500A. Wish me luck! ...I may end-up needing a bigger hammer. :confused:
     
  12. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,648
    762
    Hey Techni, relax!

    The worst you could do is to get angry with any piece of gear...but if worst comes to worst I wonder if you could convince him to lend his hammer to you o_O
     
  13. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,648
    762
    As recommended by Walter Jung in one of his books.
     
Loading...