V

RF

A

RI

V

1.8

A

3.6

0.5

V

VOUT

A

VIN

Vsup+

+

VOUT

RF

VIN

RI

Vsup-

Copyright © 2016, Texas Instruments Incorporated

9

LP358, LP2904

www.ti.com

SLOS475A – AUGUST 2005 – REVISED MAY 2017

Product Folder Links: LP358 LP2904

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9 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.

9.1 Application Information

The LP358 and LP2904 operational amplifiers are useful in a wide range of signal conditioning applications due

to the wide VCC range. Inputs can be powered before VCC for flexibility in multiple supply circuits.

9.2 Typical Application

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

on the input, and makes the voltage a negative voltage. In the same manner, the amplifier also makes negative

voltages positive.

Figure 4. Application Schematic

9.2.1 Design Requirements

The supply voltage must be selected such that it is larger than the input voltage range and output range. For

instance, this application scales a signal of ±0.5 V to ±1.8 V. Setting the supply at ±12 V is sufficient to

accommodate this application

9.2.2 Detailed Design Procedure

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

(1)

(2)

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

because the amplifier circuit uses currents in the milliamp range. This ensures the part does not draw too much

current. This example uses 10 kΩ for RI, so 36 kΩ is used for RF; this is determined by Equation 3.

(3)