Vsup+

+

RF

RI

Vsup-

LM158, LM158A, LM258, LM258A

LM358, LM358A, LM2904, LM2904V

SLOS068T – JUNE 1976 – REVISED APRIL 2015

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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 LMx58 and LM2904 operational amplifiers are useful in a wide range of signal conditioning applications.

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

negative voltages positive.

Figure 13. Application Schematic

9.2.1 Design Requirements

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

instance, this application will scale 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, choose a value for RI or RF. Choosing a value in the kilohm range is

desirable because the amplifier circuit will use currents in the milliamp range. This ensures the part will not draw

too much current. This example will choose 10 k

Ω for RI which means 36 kΩ will be used for RF. This was

determined by Equation 3.

(3)

14

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