LM139: Input voltage range limitations not in PSpice model

John Vedder

Prodigy 50 points

Part Number: LM139

The App Note SNOAA35 does an excellent job of describing the input voltage limitations of the LM139A.

I downloaded the PSpice model from the LM139A page, but it does not exhibit these limitations.

Does anyone know of a Spice model for the LM139 that does?

Thanks,
-John

over 3 years ago

0 Paul Grohe over 3 years ago

TI__Mastermind 49966 points

Hello John,

The model, like the LM139 itself, is simple.

What exactly are you trying to model? What are you expecting to see?

0 John Vedder over 3 years ago in reply to Paul Grohe

Prodigy 50 points

The App Note states that if both inputs exceed the upper input voltage range, the comparator operation ceases and the output goes low.

For the LM139, this should happen if both inputs are above (Vcc - 1V). The spice models for some other comparators (for example, LT1017) show this behavior.

Thanks,
-John

0 Chuck Sins over 3 years ago in reply to John Vedder

TI__Mastermind 23425 points

John

you are correct, the model is not accurately showing what the comparator does when both inputs are outside the range.

attached is a TINA model for LM139 that has this modeled correctly.

when both inputs are greater than VCC - 1.5V, the output will go low. The model is for 25C analysis, that is why it is not set to VCC-2V.

ChuckLM139.TSC

0 Joe Vanacore over 3 years ago in reply to Chuck Sins

TI__Genius 10545 points

Hi John,

Since there haven't been any replies to this thread, I will assume we have answered your questions. If you have any further questions, please respond to this thread or open another.

Thanks,

Joe

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LM139: Input voltage range limitations not in PSpice model