TLC081 - problem with SPICE model from TI

Discussion in 'General Electronics Chat' started by eblc1388, Oct 21, 2011.

  1. eblc1388

    Thread Starter Senior Member

    Nov 28, 2008
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    I wanted to use a single supply opamp to sense near 0V(as a replacement for LM324) so I downloaded the data sheet and SPICE model of TLC081 from TI.

    It is stated in the data sheet that the common mode voltage of TLC08x includes 0V so I'm just checking how it performs via simulation in the configuration of a voltage follower with gain. The simulation result does not corresponds to what I am expecting.

    It must be a bad Spice model from TI or compatibility of models in LTSpice then. The circuit and model is attached if you want to have a go.

    So, have anyone ever used the TLC08x for sensing signal down to 0V?

    [​IMG]
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Gee, it's almost like that's a model for a completely different IC.

    If you give it a negative supply of -1.2v, it cleans up quite a bit - but you shouldn't have to do that.

    Input offset is ~5.1 to 5.2mV; it's supposed to be ~60uV according to page 1 of the datasheet - but then later in the detailed specs, input offset can be 390uV (typ) to 1400uV, 1900uV, or 2000uV depending on A or no rev model and temp - I'm not crazy about the way that was spec'd.

    Something tells me that the documentation and model for this part were a rush job.

    However, it may be that the model works properly in Tina-TI - which I don't have installed.

    [eta]
    Out of curiousity, I installed Tina-TI 9 freshly downloaded from TI's site - wouldn't you know it; the TLC081 model was not included with the Tina-TI library!
     
    Last edited: Oct 21, 2011
  3. eblc1388

    Thread Starter Senior Member

    Nov 28, 2008
    1,542
    102
    Thanks Sgt for going into such trouble.

    There is something not quite right there. The TLC082 is advertised elsewhere on the internet as having maximum offset voltage of 1.9mV instead of 60uV mentioned in the data sheet. Looks like the data sheet was produced ahead of the actual manufacturing or maybe someone clever has taken two sets of offset voltage at various conditions and then done an average on it.

    Let's hope that someone has actually used the TLC082 and can report whether its input did work at GND or not.
     
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