AP358S 데이터 시트보기 (PDF) - Anachip Corporation

부품명

상세내역

일치하는 목록

AP358S

Low Power Dual Operational Amplifiers

Anachip Corporation 

Low Power Dual Operational Amplifiers

AP358

„ Application Information

The AP358 series are op amps which operate with

only a single power supply voltage, have

true-differential inputs, and remain in the linear

mode with an input common-mode voltage of 0 VDC.

These amplifiers operate over a wide range of

power supply voltage with little change in

performance characteristics. At 25°C amplifier

operation is possible down to a minimum supply

voltage of 2.3 VDC.

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 from large differential input voltages.

The differential input voltage may be larger than V+

without damaging the device. Protection should be

provided to prevent the input voltages from going

negative more than -0.3 VDC (at 25°C). An input

clamp 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 accomodated using

the worst-case non-inverting unity gain connection.

Large closed loop gains or resistive isolation should

be used if larger load capacitance must be driven

by the amplifier.

The bias network of the AP358 establishes a drain

current which is independent of the magnitude of

the power supply voltage over the range of 3 VDC to

30 VDC.

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+/2)

will allow operation above and 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.

Anachip Corp.

www.anachip.com.tw

11/13

Rev. 1.1 Oct 8, 2004

Share Link: