LMV7235, LMV7239, LMV7239-Q1

SNOS532N – SEPTEMBER 2000 – REVISED APRIL 2015

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8 Detailed Description

8.1 Overview

The LMV7235, LMV7239 and LMV7239-Q1 are ultra low power, low voltage, 75-ns comparators. They are

guaranteed to operate over the full supply voltage range of 2.7 V to 5.5 V. These devices achieve a 75-ns

propagation delay while consuming only 65 µA of supply current at 5 V.

The LMV7235, LMV7239 and LMV7239-Q1 have a greater than rail-to-rail common mode voltage range. The

input common mode voltage range extends 200 mV below ground and 200 mV above supply, allowing both

ground and supply sensing.

8.2 Functional Block Diagram

Simplified Schematic of LMV7239

8.3 Feature Description

8.3.1 Input Stage

The LMV7235, LMV7239 and LMV7239-Q1 are rail-to-rail input and output. The typical input common mode

voltage range of

−0.2 V below the ground to 0.2 V above the supply. The LMV7235, LMV7239 and LMV7239-Q1

use a complimentary PNP and NPN input stage in which the PNP stage senses common mode voltage near V

−

common mode limit, the parasitic PN junction formed by the substrate and the base of the PNP will turn on

resulting in an increase of input bias current.

If one of the inputs goes above the positive common mode limit, the output will still maintain the correct logic

level as long as the other input stays within the common mode range. However, the propagation delay will

increase. When both inputs are outside the common mode voltage range, current saturation occurs in the input

stage, and the output becomes unpredictable.

The propagation delay does not increase significantly with large differential input voltages. However, large

differential voltages greater than the supply voltage should be avoided to prevent damage to the input stage.

8.3.2 Output Stage, LMV7239 and LMV7239-Q1

ground, causing high output sinking or sourcing current during the transition.

10

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Product Folder Links: LMV7235 LMV7239 LMV7239-Q1