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Original question:

TINA/Spice/LMC6762: Voltage input violation

TINA/Spice/LMC6762: Supply rail domain question

Andras Magyar
Prodigy 40 points
Part Number: LMC6762
Other Parts Discussed in Thread: TINA-TI, LM311,

Tool/software: TINA-TI or Spice Models

Hi,

I have a design with this comparator and I used a +5V and -5V voltages for supply the rails. I think as long as the differential maximum 16V is not violated I can used this device with negative voltage as well. Am I right?

  • 0
    TI__Mastermind 25010 points

    Andras

    You are correct. Split supplies are allowed.  I just want to make sure that you are aware that the output of the comparator will also switch between your split supply rails of +/-5V.  So output high will be +5V and output low will be -5V since the output stage is push-pull.

    Chuck

  • 0 in reply to Chuck Sins
    Prodigy 40 points

    That's for sure Chuck, that is why I implemented a fet at its output to level shift to 0-5V the comparision.

    Thanks,

    Andras

  • 0 in reply to Andras Magyar
    TI__Mastermind 25010 points
    Andras
    thanks for the response. I assume that you selected the LMC6762 for it's low power and operating voltage range, but I wanted to mention another very old part that solves this dilemma of level shifting in one part. Are you familiar with the LM311 family where the output transistor's collector and emitter are both bonded out. Now your power supply can be +/-5V and the output can swing from 0 to 5V. Pretty cool but at a higher quiescent current for sure.
    www.ti.com/.../lm311.pdf
    Chuck