LMV331M5XSLASHNOPB datasheet(10/38 Pages) TI1

10 / 38 page

LMV331-N, LMV339-N, LMV393-N

SNOS018H – AUGUST 1999 – REVISED DECEMBER 2014

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8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

8.1.1 Basic Comparator

The comparator compares the input voltage (VIN) at the non-inverting pin to the reference voltage (VREF) at the

inverting pin. If VIN is less than VREF, the output voltage (VO) is at the saturation voltage. On the other hand, if VIN

is greater than VREF, the output voltage (VO) is at VCC.

Figure 10. Basic Comparator

8.1.2 Comparator With Hysteresis

The basic comparator configuration may oscillate or produce a noisy output if the applied differential input

voltage is near the comparator's offset voltage. This usually happens when the input signal is moving very slowly

across the switching threshold of the comparator. This problem can be prevented by the addition of hysteresis or

positive feedback.

8.1.2.1 Inverting Comparator With Hysteresis

The inverting comparator with hysteresis requires a three resistor network that are referenced to the supply

voltage VCC of the comparator. When Vin at the inverting input is less than Va, the voltage at the non-inverting

node of the comparator (Vin < Va), the output voltage is high (for simplicity assume VO switches as high as VCC).

The three network resistors can be represented as R1//R3 in series with R2. The lower input trip voltage Va1 is

defined as:

(1)

When Vin is greater than Va (Vin > Va), the output voltage is low very close to ground. In this case the three

network resistors can be presented as R2//R3 in series with R1. The upper trip voltage Va2 is defined as:

(2)

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