ANALOG DEVICES AD8643-EP Service Manual
Low Power, Rail-to-Rail,
FEATURES
Low supply current: 250 μA maximum
Very low input bias current: 1 pA maximum
Low offset voltage: 750 μV maximum
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
ENHANCED PRODUCT FEATURES
Supports defense and aerospace applications
(AQEC standard)
Military temperature range (−55°C to +125°C)
Controlled manufacturing baseline
1 assembly/test site
1 fabrication site
Enhanced product change notification
Qualification data available on request
Output Precision JFET Amplifier
AD8643-EP
PIN CONFIGURATION
1
OUT A
2
–IN A
3
+IN A
+IN B
–IN B
OUT B
AD8643-EP
TOP VIEW
4
V+
(Not to Scal e)
5
6
7
Figure 1. 14-Lead SOIC (R-14)
14
13
12
11
10
9
8
OUT D
–IN D
+IN D
V–
+IN C
–IN C
OUT C
09590-103
APPLICATIONS
Line-/battery-powered instruments
Photodiode amplifiers
Precision current sensing
Precision filters
Portable audio
GENERAL DESCRIPTION
The AD8643-EP is a low power, precision JFET input amplifier
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 digital-to-analog
converters (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 AD8643-EP is suitable for applications using multichannel
boards that require low power to manage heat. Other applications
include photodiodes and battery management.
The AD8643-EP is fully specified over the military temperature
range of −55°C to +125°C. This device is available in a 14-lead SOIC.
Additional applications information is available in the AD8643
data sheet.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 ©2011 Analog Devices, Inc. All rights reserved.
AD8643-EP
TABLE OF CONTENTS
Features.............................................................................................. 1
Enhanced Product Features ............................................................ 1
Applications....................................................................................... 1
Pin Configuration............................................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
REVISION HISTORY
1/11—Revision 0: Initial Version
Electrical Characteristics..............................................................3
Absolute Maximum Ratings ............................................................5
Thermal Resistance.......................................................................5
ESD Caution...................................................................................5
Typical Performance Characteristics..............................................6
Outline Dimensions....................................................................... 12
Ordering Guide .......................................................................... 12
Rev. 0 | Page 2 of 12
AD8643-EP
SPECIFICATIONS
ELECTRICAL CHARACTERISTICS
VS = 5.0 V, VCM = 2.5 V, TA = 25°C, unless otherwise noted.
Table 1.
Parameter Symbol Test Conditions/Comments Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage VOS 50 1000 μV
−55°C < TA < +85°C 1.8 mV
+85°C < TA < +125°C, VCM = 1.5 V 1.9 mV
Input Bias Current IB 0.25 1 pA
−55°C < TA < +125°C 180 pA
Input Offset Current IOS 0.5 pA
−55°C < TA < +125°C 60 pA
Input Voltage Range 0 3 V
Common-Mode Rejection Ratio CMRR VCM = 0 V to 2.5 V 74 93 dB
Large Signal Voltage Gain AVO R
Offset Voltage Drift ΔVOS/ΔT −55°C < TA < +125°C 2.5 μV/°C
OUTPUT CHARACTERISTICS
Output Voltage High VOH 4.95 V
I
Output Voltage Low VOL 0.05 V
I
Output Current I
±6 mA
OUT
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = 5 V to 26 V 90 107 dB
Supply Current/Amplifier ISY 195 250 μA
−55°C < TA < +125°C 270 μA
DYNAMIC PERFORMANCE
Slew Rate SR 2 V/μs
Gain Bandwidth Product GBP 2.5 MHz
Phase Margin Ø
m
NOISE PERFORMANCE
Voltage Noise eN p-p f = 0.1 Hz to 10 Hz 4.0 μV p-p
Voltage Noise Density eN f = 1 kHz 28.5 nV/√Hz
Current Noise Density iN f = 1 kHz 0.5 fA/√Hz
= 10 kΩ, VO = 0.5 to 4.5 V 80 140 V/mV
L
= 1 mA, −55°C to +125°C 4.94 V
L
= 1 mA, −55°C to +125°C 0.01 0.05 V
L
50 Degrees
Rev. 0 | Page 3 of 12
AD8643-EP
VS= ±13 V, VCM = 0 V, TA = 25°C, unless otherwise noted.
Table 2.
Parameter Symbol Test Conditions/Comments Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage VOS 70 1000 μV
−55° < TA < +125°C 1.8 mV
Input Bias Current IB 0.25 1 pA
–55°C < TA < +125°C 260 pA
Input Offset Current IOS 0.5 pA
−55°C < TA < +125°C 65 pA
Input Voltage Range −13 +10 V
Common-Mode Rejection Ratio CMRR VCM = −13 V to +10 V 90 107 dB
Large Signal Voltage Gain AVO R
Offset Voltage Drift ΔVOS/ΔT −55°C < TA < +125°C 2.5 μV/°C
OUTPUT CHARACTERISTICS
Output Voltage High VOH 12.95 V
I
Output Voltage Low VOL −12.95 V
I
Output Current I
±12 mA
OUT
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = ±2.5 V to ±13 V 90 107 dB
Supply Current/Amplifier ISY 200 290 μA
−55°C < TA < +125°C 330 μA
DYNAMIC PERFORMANCE
Slew Rate SR 3 V/μs
Gain Bandwidth Product GBP 3.5 MHz
Phase Margin
Ø
m
NOISE PERFORMANCE
Voltage Noise eN p-p f = 0.1 Hz to 10 Hz 4.2 μV p-p
Voltage Noise Density eN f = 1 kHz 27.5 nV/√Hz
Current Noise Density iN f = 1 kHz 0.5 fA/√Hz
= 10 kΩ, VO = –11 V to +11 V 215 290 V/mV
L
= 1 mA, −55°C to +125°C 12.94 V
L
= 1 mA, −55°C to +125°C −12.94 V
L
60 Degrees
Rev. 0 | Page 4 of 12
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