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LMV393-Q1: Window comparator in datasheet.

Taoufiq Bellamine
Prodigy 240 points
Part Number: LMV393-Q1

Hello,

I am using the LMV393LV as a window comparator. I looked at the schematic you had on the datasheet and it appears to me that the in+ and in- are flipped on the amps. Would you please confirm that it's a typo.

Below is a photo of the proposed schematic on the datasheet.

Thanks.

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  • 0
    TI__Mastermind 49946 points

    Hello Taufiq,

    Do not add an inversion due to the MOSFET. Some readers may assume an inversion. The MOSFETS were not intended to add an inversion, but show the open drain output stage (they are inside the "box"). We may need to clarify that...

    For each comparator, the output will go low when the negative input exceeds the positive input.

    So when VIN is 0V, the negative input of the lower comparator is at VTH- (+1.1V), and the positive input is 0V, so the output is low. The upper comparator has the positive input at VTH+ (+2.2V), and the negative input at 0V, so the output is high. Since the outputs are OR'ed, the resulting output is low (outside window).

    When VIN is 1.5V, the negative input of the lower comparator is at VTH- (+1.1V), and the positive input is +1.5V, so the output is now high. The upper comparator has the positive input at VTH+ (+2.2V), and the negative input at 1.5V, so the output is high. Since the outputs are OR'ed, the resulting output is high (inside window).

    When VIN is 2.5V, the negative input of the lower comparator is at VTH- (+1.1V), and the positive input is +2.5V, so the output is high. The upper comparator has the positive input at VTH+ (+2.2V), and the negative input at +2.5V, so the output is low. Since the outputs are OR'ed, the resulting output is low (outside window).

    So it is correct.