Low-Cost, High-Slew-Rate,

Rail-to-Rail I/O Op Amps in SC70

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5

NAME

FUNCTION

MAX4490

1

IN+

Noninverting Input

PIN

2

Negative Supply Input. Connect to ground for single-supply operation.

3

IN-

Inverting Input

–

INA-

Inverting Input to Amplifier A

–

INA+

Noninverting Input to Amplifier A

5

Positive Supply Input

4

OUT

Amplifier Output

–

INC+, IND+

Noninverting Inputs to Amplifiers C and D

–

OUTB

Amplifier B Output

–

INB-

Inverting Input to Amplifier B

–

INB+

Noninverting Input to Amplifier B

–

OUTA

Amplifier A Output

Pin Description

MAX4492

–

11

–

2

3

4

–

10, 12

7

6

5

1

MAX4491

–

4

–

2

3

8

–

–

7

6

5

1

–

–

9, 13

INC-, IND-

Inverting Inputs to Amplifiers C and D

–

–

8, 14

OUTC, OUTD

Amplifiers C and D Outputs

Detailed Description

Rail-to-Rail Input Stage

The MAX4490/MAX4491/MAX4492 CMOS operational

amplifiers have parallel-connected N- and P-channel

differential input stages that combine to accept a com-

mon-mode range extending to both supply rails. The N-

channel stage is active for common-mode input

channel stage is active for common-mode input volt-

Rail-to-Rail Output Stage

The MAX4490/MAX4491/MAX4492 CMOS operational

amplifiers feature class-AB push-pull output stages that

can drive a 100k

Ω load to within 1.5mV of either supply

rail. Short-circuit output current is typically ±50mA.

Figures 1a and 1b show the typical temperature depen-

dence of output source and sink currents, respectively,

tive drive capability is (2.5 - 0.1) / 2.2 = 1.1k

Ω. For the

same application, resistive drive capability is 2.2k

Ω

Applications Information

Power-Supply Considerations

The MAX4490/MAX4491/MAX4492 operate from a sin-

gle +2.7V to +5.5V supply or from dual ±1.35V to

±2.75V supplies with typically 800µA supply current

per amplifier. A high power-supply rejection ratio of

100dB allows for extended operation from a decaying

battery voltage, thereby simplifying designs for

portable applications. For single-supply operation,

bypass the power supply with a 0.1µF ceramic capaci-

tion, bypass each supply to ground.

Input Capacitance

One consequence of the parallel-connected differential

input stages for rail-to-rail operation is a relatively large