Single/Dual/Quad, Low-Cost, SOT23,

Micropower, Rail-to-Rail I/O Op Amps

8

_______________________________________________________________________________________

_______________Detailed Description

Rail-to-Rail Input Stage

The MAX4040–MAX4044 have rail-to-rail inputs and

rail-to-rail output stages that are specifically designed

for low-voltage, single-supply operation. The input

stage consists of separate NPN and PNP differential

stages, which operate together to provide a common-

mode range extending to both supply rails. The

crossover region of these two pairs occurs halfway

cally 200µV. Low operating supply voltage, low supply

current, rail-to-rail common-mode input range, and rail-

to-rail outputs make this family of operational amplifiers

an excellent choice for precision or general-purpose,

low-voltage battery-powered systems.

Since the input stage consists of NPN and PNP pairs,

the input bias current changes polarity as the common-

mode voltage passes through the crossover region.

Match the effective impedance seen by each input to

reduce the offset error caused by input bias currents

flowing through external source impedances (Figures

1a and 1b). The combination of high source impedance

plus input capacitance (amplifier input capacitance

plus stray capacitance) creates a parasitic pole that

produces an underdamped signal response. Reducing

input capacitance or placing a small capacitor across

the feedback resistor improves response in this case.

______________________________________________________________Pin Description

1

—

—

—

—

2

4

4

4

11

Negative Supply. Tie to ground for

single-supply operation.

3

—

Amplifier Output. High impedance

when in shutdown mode.

OUT

—

—

—

4

—

—

—

—

Inverting Input

IN-

Noninverting Input

IN+

5

10

8

14

4

—

—

—

5, 7,

8, 10

—

No Connection. Not internally con-

nected.

N.C.

—

—

Positive Supply

—

—

—

—

1, 9

1, 7

1, 13

1, 7

Outputs for Amplifiers A and B. High

impedance when in shutdown mode.

OUTA,

OUTB

Shutdown Input. Drive high, or tie to

to place device in shutdown mode.

SHDN

—

2, 8

2, 6

2, 12

2, 6

—

3, 7

3, 5

3, 11

3, 5

Noninverting Inputs to Amplifiers A

and B

INA+,

INB+

—

5, 6

Inverting Inputs to Amplifiers A and B

INA-,

INB-

—

6, 9

—

—

—

—

—

8, 14

Outputs for Amplifiers C and D

OUTC,

OUTD

Shutdown Inputs for Amplifiers A

place device in shutdown mode.

SHDNA,

SHDNB

—

—

—

—

9, 13

—

—

—

—

10, 12

Noninverting Inputs to Amplifiers C

and D

INC+,

IND+

Inverting Inputs to Amplifiers C and D

INC-,

IND-

6

4

3

2

7

1, 5

8

—

—

—

—

—

—

—

6

4

3

2

7

1, 5, 8

—

—

—

—

—

—

—

—

MAX4043

MAX4044

PIN

µMAX

MAX4042

SO

MAX4041

FUNCTION

NAME

SOT23-5

MAX4040

SO/µMAX