_______________Detailed Description

The MAX4249–MAX4257 single-supply operational

amplifiers feature ultra-low noise and distortion while

consuming very little power. Their low distortion and

low noise make them ideal for use as preamplifiers in

wide dynamic-range applications, such as 16-bit ana-

log-to-digital converters (see

Typical Operating Circuit).

Their high input impedance and low noise are also use-

ful for signal conditioning of high-impedance sources,

such as piezoelectric transducers.

These devices have true rail-to-rail output operation,

drive loads as low as 1k

Ω while maintaining DC accura-

cy, and can drive capacitive loads up to 400pF without

oscillation. The input common-mode voltage range

rail. The push/pull output stage maintains excellent DC

characteristics, while delivering up to ±5mA of current.

The MAX4250–MAX4254 are unity-gain stable, whereas

the MAX4249/MAX4255/MAX4256/MAX4257 have a

higher slew rate and are stable for gains

≥10V/V. The

MAX4249/ MAX4251/MAX4253/MAX4256 feature a low-

power shutdown mode, which reduces the supply cur-

rent to 0.5µA and disables the outputs.

Low Distortion

Many factors can affect the noise and distortion that the

device contributes to the input signal. The following

guidelines offer valuable information on the impact of

design choices on Total Harmonic Distortion (THD).

Choosing proper feedback and gain resistor values for

a particular application can be a very important factor

in reducing THD. In general, the smaller the closed-

loop gain, the smaller the THD generated, especially

when driving heavy resistive loads. Large-value feed-

back resistors can significantly improve distortion. The

THD of the part normally increases at approximately

20dB per decade, as a function of frequency.

Operating the device near or above the full-power

bandwidth significantly degrades distortion.

Referencing the load to either supply also improves the

part’s distortion performance, because only one of the

MOSFETs of the push/pull output stage drives the out-

put. Referencing the load to mid-supply increases the

part’s distortion for a given load and feedback setting.

(See the Total Harmonic Distortion vs. Frequency graph

in the

Typical Operating Characteristics.)

SOT23, Single-Supply, Low-Noise,

Low-Distortion, Rail-to-Rail Op Amps

8

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Pin Description

Amplifier Output

6

1

1, 9

1, 7

1, 7, 8, 14

1, 13

OUT, OUTA,

OUTB, OUTC,

OUTD

3, 7

3, 5

3, 5, 10, 12

3, 11

IN+, INA+, INB+,

INC+, IND+

Noninverting Amplifier Input

3

3

4

4

11

4

Negative Supply. Connect

to ground for single-supply

operation.

4

2

2, 8

2, 6

2, 6, 9, 13

2, 12

IN-, INA-, INB-,

INC-, IND-

5, 6

—

—

6, 9

SHDN,

SHDNA,

SHDNB

Shutdown Input. Connect to

normal operation (amplifier(s)

enabled).

8

—

10

8

Inverting Amplifier Input

2

4

4

14

Positive Supply

7

5

—

—

—

5, 7, 8, 10

N.C.

No Connection. Not internally

connected.

1, 5

—

PIN

MAX4249/MAX4253

MAX4252

MAX4257

10 µMAX

14 SO

MAX4254

MAX4250

MAX4255

MAX4251

MAX4256

14 SO

8 µMAX/SO

5 SOT23

NAME

FUNCTION