Rainbow Electronics MAX4329 User Manual

Page 8

MAX4322/MAX4323/MAX4326/MAX4327/MAX4329

Single/Dual/Quad, Low-Cost, SOT23,
Low-Power, Rail-to-Rail I/O Op Amps

_______________________________________________________________________________________

Pin Description

__________ Applications Information

Rail-to-Rail Input Stage

Devices in the MAX4322/MAX4323/MAX4326/MAX4327/
MAX4329 family of high-speed amplifiers have rail-to-
rail input and output stages designed for low-voltage,
single-supply operation. The input stage consists of
separate NPN and PNP differential stages, which com-
bine to provide an input common-mode range extend-
ing to the supply rails. The PNP stage is active for input
voltages close to the negative rail, and the NPN stage
is active for input voltages near the positive rail. The
input offset voltage is typically below 250µV. The

switchover transition region, which occurs near V

/ 2,

has been extended to minimize the slight degradation in
CMRR caused by the mismatch of the input pairs. Their
low offset voltage, high bandwidth, and rail-to-rail com-
mon-mode range make these op amps excellent choices
for precision, low-voltage, data-acquisition systems.

Since the input stage switches between the NPN and
PNP pairs, the input bias current changes polarity as
the input voltage passes through the transition region.
To reduce the offset error caused by input bias cur-
rents flowing through external source impedances,
match the effective impedance seen by each input
(Figures 1a, 1b). High source impedances, together

Inverting Inputs for amps 1
and 2

IN1-, IN2-

Noninverting Inputs for amps
1 and 2

IN1+, IN2+

Shutdown Control for amps 1
and 2. Tie high or leave float-
ing to enable amplifier.

SHDN1,

SHDN2

Outputs for amps 3 and 4

OUT3,

OUT4

Inverting Inputs for amps 3
and 4

IN3-, IN4-

Positive Supply

No Connection

N.C.

Shutdown Control. Tie high or
leave floating to enable
amplifier.

SHDN

Outputs for amps 1 and 2

OUT1,

OUT2

Inverting Input

IN-

Noninverting Input

IN+

Negative Supply. Ground for
single-supply operation.

Output

OUT

SOT23-5

MAX4326

—

µMAX

2, 6

3, 5

—

1, 7

—

2, 8

3, 7

5, 6

—

1, 9

—

2, 12

3, 11

5, 9

—

5, 7, 8,

—

1, 13

—

Noninverting Inputs for amps
3 and 4

IN3+, IN4+

—

MAX4329

2, 6

3, 5

—

8, 14

9, 13

—

1, 7

—

10, 12

SO/µMAX

—

1, 5, 8

—

MAX4322

MAX4327

NAME

MAX4323

SOT23-6

—

SO/µMAX

—

1, 5

—

PIN

FUNCTION