LM358

LOW POWER DUAL OPERATIONAL AMPLIFIERS

LM358

Document number: DS35167 Rev. 2 - 2

12 of 14

www.diodes.com

February 2011

© Diodes Incorporated

Application Information

The LM358 series are op amps operate with only a single

power supply voltage, have true-differential inputs, and

remain in the linear mode with an input common-mode

range of power supply voltage with little change in

performance characteristics. At 25°C amplifier operation

Precautions should be taken to insure that the power

supply for the integrated circuit never becomes reversed

in polarity or that the unit is not inadvertently installed

backwards in a test socket as an unlimited current surge

through the resulting forward diode within the IC could

cause fusing of the internal conductors and result in a

destroyed unit.

Large

differential

input

voltages

can

be

easily

accommodated

and,

as

input

differential

voltage

protection diodes are not needed, no large input currents

result. The differential input voltage may be larger than

V

provided to prevent the input voltages from going

diode with a resistor to the IC input terminal can be used.

To reduce the power supply current drain, the amplifiers

have a class A output stage for small signal levels which

converts to class B in a large signal mode. This allows

the amplifiers to both source and sink large output

currents. Therefore both NPN and PNP external current

boost transistors can be used to extend the power

capability of the basic amplifiers. The output voltage

needs to raise approximately 1 diode drop above ground

to bias the on-chip vertical PNP transistor for output

current sinking applications.

For AC applications, where the load is capacitively

coupled to the output of the amplifier, a resistor should

be used, from the output of the amplifier to ground to

increase the class A bias current and prevent crossover

distortion. Where the load is directly coupled, as in

DC applications, there is no crossover distortion.

Capacitive loads which are applied directly to the output

of the amplifier reduce the loop stability margin. Values of

50pF can be accommodated using the worst-case non-

inverting unity gain connection. Large closed loop gains

or resistive isolation should be used if a larger load

capacitance must be driven by the amplifier.

The bias network of the LM358 establishes a drain

current which is independent of the magnitude of the

Output short circuits either to ground or to the positive

power supply should be of short time duration. Units can

be destroyed, not as a result of the short circuit current

causing metal fusing, but rather due to the large increase

in IC chip dissipation which will cause eventual failure

due to excessive function temperatures. Putting direct

short-circuits on more than one amplifier at a time will

increase the total IC power dissipation to destructive

levels, if not properly protected with external dissipation

limiting resistors in series with the output leads of the

amplifiers. The larger value of output source current

which is available at 25°C provides a larger output

current capability at elevated temperatures (see typical

performance characteristics) than a standard IC op amp.

The

circuits

presented

in

the

section

on

typical

applications emphasize operation on only a single power

supply voltage. If complementary power supplies are

available, all of the standard op amp circuits can be

used. In general, introducing a pseudo-ground (a bias

voltage reference of V

below this value in single power supply systems. Many

application circuits are shown which take advantage of

the wide input common-mode voltage range which

includes ground. In most cases, input biasing is not

required and input voltages which range to ground can

easily be accommodated.