Low Power, Rail-to-Rail Output, Precision
JFET Amplifiers
Data Sheet
AD8641/AD8642/AD8643
FEATURES
PIN CONFIGURATIONS
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
OUT
VEE
+IN
1
2
3
5
VCC
–IN
AD8641
TOP VIEW
(Not to Scale)
4
Figure 1. 5-Lead SC70 (KS-5)
Unity-gain stable
No phase reversal
SC70 package
NC
–IN
1
2
3
4
8
7
6
5
NC
AD8641
VCC
OUT
NC
+IN
TOP VIEW
(Not to Scale)
VEE
NC = NO CONNECT
APPLICATIONS
Figure 2. 8-Lead SOIC (R-8)
Line-/battery-powered instruments
Photodiode amplifiers
Precision current sensing
Medical instrumentation
Industrial controls
Precision filters
OUT A
–IN A
+IN A
V–
1
2
3
4
8
7
6
5
V+
AD8642
OUT B
–IN B
+IN B
TOP VIEW
(Not to Scale)
Figure 3. 8-Lead SOIC (R-8)
Portable audio
OUT A
–IN A
+IN A
V–
1
2
3
4
8
7
6
5
V+
ATE
AD8642
OUT B
–IN B
+IN B
TOP VIEW
(Not to Scale)
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.
Figure 4. 8-Lead MSOP (RM-8)
OUT A
–IN A
+IN A
V+
1
2
3
4
5
6
7
14 OUT D
13 –IN D
12 +IN D
11 V–
AD8643
TOP VIEW
(Not to Scale)
+IN B
–IN B
OUT B
10 +IN C
9
8
–IN C
OUT C
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.
Figure 5. 14-Lead SOIC (R-14)
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.
12 –IN D
–IN A
+IN A
V+
1
2
3
4
PIN 1
INDICATOR
11 +IN D
10 V–
AD8643
TOP VIEW
+IN B
9 +IN C
NOTES
1. NC = NO CONNECT.
2. EXPOSED PAD SHOULD BE CONNECTED TO V+.
Figure 6. 16-Lead LFCSP (CP-16) (Not Drawn to Scale)
Rev. E
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