Trying to get LM311 comparator into LTspice

[24vtingle]

Hi,
I have made the symbol, with correct numbering as per subckt file.
I then pasted the subckt file into the LTspice schem.
I then right clicked the symbol and made "prefix" be "x" and "value" be "LM311".

However, it still doesnt work , as attached.

I got the subckt file from ti.com

LM311 data sheet, product information and support | TI.com

TI’s LM311 is a High Speed, 30V, Differential Comparator With Strobes. Find parameters, ordering and quality information

www.ti.com

 

[FvM]

To get an idea if I don't have Ltspice at hand right now, what's observed error?

 

[24vtingle]

Thanks, the output is not right....i have 2.5V into (-), and am hitting (+) with a 0v,5v square wave and i am just getting weird spikes on the output with a 2.5V.
level.
...Aaah...maybe i have gone outside the common mode range for inputs...just tried square wave 2v to 3v and its working. Sorry.

Even so, wow, i didnt realise LM311 was that useless as not to be able to accept a 0v,5v square wave input?

LM311 data sheet, product information and support | TI.com

TI’s LM311 is a High Speed, 30V, Differential Comparator With Strobes. Find parameters, ordering and quality information

www.ti.com

 

[dick_freebird]

Supplies and ICMR?

 

[24vtingle]

Thanks, looks like it yes.

 

[D.A.(Tony)Stewart]

Why not attenuate the input?

 

[FvM]

The waveforms produced by post #1 simulation circuit are completely implausible and are unlikely representing LM311 real behaviour. In earlier years, TI published a different macromodel which generates different behaviour.

It's no true transistor level model, therefore it can't prove that LM311 is free of phase reversal, but I'm rather sure that it is.

* http://focus.ti.com/docs/prod/folders/print/lm311.html
* LM311 VOLTAGE COMPARATOR "MACROMODEL" SUBCIRCUIT
* CREATED USING PARTS VERSION 4.03 ON 03/07/90 AT 08:15
* REV (N/A)
* CONNECTIONS:   NON-INVERTING INPUT
*                | INVERTING INPUT
*                | | POSITIVE POWER SUPPLY
*                | | | NEGATIVE POWER SUPPLY
*                | | | | OPEN COLLECTOR OUTPUT
*                | | | | | OUTPUT GROUND
*                | | | | | |
.SUBCKT LM311    1 2 3 4 5 6
*
  F1    9  3 V1 1
  IEE   3  7 DC 100.0E-6
  VI1  21  1 DC .45
  VI2  22  2 DC .45
  Q1    9 21  7 QIN
  Q2    8 22  7 QIN
  Q3    9  8  4 QMO
  Q4    8  8  4 QMI
.MODEL QIN PNP(IS=800.0E-18 BF=500)
.MODEL QMI NPN(IS=800.0E-18 BF=1002)
.MODEL QMO NPN(IS=800.0E-18 BF=1000 CJC=1E-15 TR=102.5E-9)
  E1   10  6  9  4  1
  V1   10 11 DC 0
  Q5    5 11  6 QOC
.MODEL QOC NPN(IS=800.0E-18 BF=103.5E3 CJC=1E-15 TF=11.60E-12 TR=48.19E-9)
  DP    4  3 DX
  RP    3  4 6.667E3
.MODEL DX  D(IS=800.0E-18)
*
.ENDS

 

[danadakk]

LM311 Datasheet on phase reversal :

Last bullet inferring phase reversal could occur ? Or at very least undefined results.

Some additional info attached.

 

[FvM]

Last bullet inferring phase reversal could occur ? Or at very least undefined results.

Thanks, thus reading the datasheet supersedes the whole thread. It clarifies that post #1 circuit (inv. input biased to Vcc/2) works as expected and Ltspice simulation with new model is wrong. Probably it's not suited for Ltspice.

 

[danadakk]

Increasingly seems to me models are not well implemented nor do we know
how to make that judgment, other than throw the dice, and see if there is
loose confirmation with benchwork.

As a profession we should demand better, after all the designers have those
tools now to accurately predict performance based on process parameters
and architecture and layout and....

Love to see a modeling expert write a paper to help train us to spot deficiencies
and model completeness, sigh.....

 

[dick_freebird]

Problem would be a nonproblem if true design
netlists were released, But the vendor is IP-jealous
and feels the need to abstract the model into a
behavioral and then neglect much actual behavior
in the name of expedience.

That op amp probably has less than 50 transistors
and solving it in full detail is not that painful on
modern CPUs. So fat that you could measure
geometries on an optical microscope and get
reasonable device values.

But that is never the plan going in - just shop the
catalog and take your fake version. With all the
usual warranty (i.e. hahahahaha).