Low Power, Rail-to-Rail Output

Precision JFET Amplifier

AD8641/AD8642/AD8643

Rev. B

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FEATURES

Low supply current: 250 µA max

Very low input bias current: 1 pA max

Low offset voltage: 750 µV max

Single-supply operation: 5 V to 26 V

Dual-supply operation: ±2.5 V to ±13 V

Rail-to-rail output

Unity-gain stable

No phase reversal

SC70 package

APPLICATIONS

Line-/battery-powered instruments

Photodiode amplifiers

Precision current sensing

Medical instrumentation

Industrial controls

Precision filters

Portable audio

ATE

GENERAL DESCRIPTION

The AD8641/AD8642/AD8643 are low power, precision JFET

input amplifiers featuring extremely low input bias current and

rail-to-rail output. The ability to swing nearly rail-to-rail at the

input and rail-to-rail at the output enables designers to buffer

CMOS DACs, ASICs, and other wide output swing devices in

single-supply systems. The outputs remain stable with

capacitive loads of more than 500 pF.

The AD8641/AD8642/AD8643 are suitable for applications

utilizing multichannel boards that require low power to manage

heat. Other applications include photodiodes, ATE reference

level drivers, battery management, and industrial controls.

The AD8641/AD8642/AD8643 are fully specified over the

extended industrial temperature range of –40°C to +125°C. The

AD8641 is available in 5-lead SC70 and 8-lead SOIC lead-free

packages. The AD8642 is available in 8-lead MSOP and 8-lead

SOIC lead-free packages. The AD8643 is available in 14-lead

SOIC and 16-lead, 3 mm × 3 mm, LFCSP lead-free packages.

PIN CONFIGURATIONS

OUT

1

+IN

3

VEE

2

VCC

5

–IN

4

AD8641

TOP VIEW

(Not to Scale)

Figure 1. 5-Lead SC70 (KS-5)

NC

1

–IN

2

+IN

3

VEE

4

NC

8

VCC

7

OUT

6

NC

5

AD8641

TOP VIEW

(Not to Scale)

NC = NO CONNECT

Figure 2. 8-Lead SOIC (R-8)

OUT A

1

–IN A

2

+IN A

3

V–

4

V+

8

OUT B

7

–IN B

6

+IN B

5

AD8642

TOP VIEW

(Not to Scale)

Figure 3. 8-Lead SOIC (R-8)

OUT A

1

–IN A

2

+IN A

3

V–

4

V+

8

OUT B

7

–IN B

6

+IN B

5

AD8642

TOP VIEW

(Not to Scale)

Figure 4. 8-Lead MSOP (RM-8)

OUT A

1

OUT D

14

–IN A

2

–IN D

13

+IN A

3

+IN D

12

V+

4

V–

11

+IN B

5

+IN C

10

–IN B

6

–IN C

9

OUT B

7

OUT C

8

TOP VIEW

(Not to Scale)

AD8643

Figure 5. 14-Lead SOIC (R-14)

12

11

10

9

+IN C

V–

+IN D

–IN D

1

–IN A

2

3

4

+IN B

V+

+IN A

AD8643

TOP VIEW

PIN 1

INDICATOR

NC = NO CONNECT

Figure 6. 16-Lead LFCSP (CP-16) (Not Drawn to Scale)