7 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, as well as validating and testing their design

implementation to confirm system functionality.

7.1 Application Information

LMV34x devices have rail-to-rail output and input range from ground to VCC – 1V. CMOS inputs provide very

low input current. Shutdown capability is an option in dual amplifier version. Operation from 2.5V to 5.5V is

possible.

7.2 Typical Application

A typical application for an operational amplifier in an inverting amplifier. This amplifier takes a positive voltage

on the input, and makes it a negative voltage of the same magnitude. In the same manner, it also makes

negative voltages positive.

Vsup+

+

VOUT

RF

VIN

RI

Vsup-

Figure 7-1. Application Schematic

7.2.1 Design Requirements

The supply voltage must be larger than the input voltage range and output range. For instance, this application

scales a signal of ±0.5V to ±1.8 V. Setting the supply at ± 2V is sufficient to accommodate this application. The

supplies can power up in any order; however, neither supply can be of opposite polarity relative to ground at any

time; otherwise, a large current can flow though the input ESD diodes. To limit current in such an occurrence, TI

highly recommends adding a series resistor to the grounded input. Vsup+ must be more positive than Vsup– at

all times; otherwise, a large reverse supply current can flow.

7.2.2 Detailed Design Procedure

Determine the gain required by the inverting amplifier using Equation 1 and Equation 2.

V

VOUT

A

VIN

(1)

V

1.8

A

3.6

0.5

(2)

Once the desired gain is determined, choose a value for RI or RF. Choosing a value in the kΩ range is desirable

because the amplifier circuit uses currents in the mA range. This makes sure the part does not draw too

much current. For this example, choose 10kΩ for RI, which means 36kΩ is used for RF. This is determined by

Equation 3.

V

RF

A

RI

(3)

LMV341, LMV342, LMV344

SLOS447J – SEPTEMBER 2004 – REVISED JUNE 2025

www.ti.com

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