Precision, Dual-Channel, JFET Input,

Rail-to-Rail Instrumentation Amplifier

Data Sheet

AD8224

Rev. D

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FEATURES

Two channels in a small 4 mm × 4 mm LFCSP

Custom LFCSP package with hidden paddle

Permits routing and vias underneath package

Allows full bias current performance

Low input currents

10 pA maximum input bias current (B grade)

0.6 pA maximum input offset current (B grade)

High CMRR

100 dB CMRR (minimum), G = 10 (B grade)

90 dB CMRR (minimum) to 10 kHz, G = 10 (B grade)

Excellent ac specifications and low power

1.5 MHz bandwidth (G = 1)

14 nV/√Hz input noise (1 kHz)

Slew rate: 2 V/µs

750 µA quiescent current per amplifier

Versatility

Rail-to-rail output

Input voltage range to below negative supply rail

4 kV ESD protection

4.5 V to 36 V single supply

±2.25 V to ±18 V dual supply

Gain set with single resistor (G = 1 to 1000)

APPLICATIONS

Medical instrumentation

Precision data acquisition

Transducer interfaces

Differential drives for high resolution input ADCs

Remote sensors

FUNCTIONAL BLOCK DIAGRAM

AD8224

1

2

3

4

12

11

10

9

5

6

7

8

13

14

15

16

–IN1

+IN1

–IN2

+IN2

Figure 1.

Table 1. In Amps and Difference Amplifiers by Category

High

Perform

Low

Cost

High

Voltage

Mil

Grade

Low

Power

Digital

Gain

AD82201

AD85531

AD628

AD620

AD6271

AD82311

AD8221

AD6231

AD629

AD621

AD8250

AD8222

AD524

AD8251

AD526

AD85551

AD624

AD85561

AD85571

GENERAL DESCRIPTION

The AD8224 is the first single-supply, JFET input instrumentation

amplifier available in the space-saving 16-lead, 4 mm × 4 mm

LFCSP. It requires the same board area as a typical single

instrumentation amplifier yet doubles the channel density

and offers a lower cost per channel without compromising

performance.

Designed to meet the needs of high performance, portable

instrumentation, the AD8224 has a minimum common-mode

rejection ratio (CMRR) of 86 dB at dc and a minimum CMRR

of 80 dB at 10 kHz for G = 1. Maximum input bias current is 10 pA

and typically remains below 300 pA over the entire industrial

temperature range. Despite the JFET inputs, the AD8224

typically has a noise corner of only 10 Hz.

With the proliferation of mixed-signal processing, the number

of power supplies required in each system has grown. Designed

to alleviate this problem, the AD8224 can operate on a ±18 V

dual supply, as well as on a single +5 V supply. The device’s rail-

to-rail output stage maximizes dynamic range on the low voltage

supplies common in portable applications. Its ability to run on a

single 5 V supply eliminates the need for higher voltage, dual

supplies. The AD8224 draws 750 µA of quiescent current per

amplifier, making it ideal for battery powered devices.

In addition, the AD8224 can be configured as a single-channel,

differential output, instrumentation amplifier. Differential

outputs provide high noise immunity, which can be useful when

the output signal must travel through a noisy environment, such

as with remote sensors. The configuration can also be used to

drive differential input ADCs. For a single-channel version, use

the AD8220.