Datasheet

AD549
Rev. H | Page 2 of 20
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Connection Diagram ....................................................................... 1
General Description ......................................................................... 1
Product Highlights ........................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3 
Absolute Maximum Ratings ............................................................ 5
ESD Caution .................................................................................. 5
Typical Performance Characteristics ............................................. 6
Functional Description .................................................................. 10
Minimizing Input Current ........................................................ 10
Circuit Board Notes ................................................................... 10
Offset Nulling ............................................................................. 11
AC Response with High Value Source and Feedback
Resistance .................................................................................... 12

Common-Mode Input Voltage Overload ............................... 12
Differential Input Voltage Overload ........................................ 13
Input Protection ......................................................................... 13
Sample and Difference Circuit to Measure Electrometer
Leakage Currents ........................................................................ 13

Photodiode Interface ................................................................. 14
Log Ratio Amplifier ................................................................... 15
Temperature Compensated pH Probe Amplifier ................... 16
Outline Dimensions ....................................................................... 18
Ordering Guide .......................................................................... 18
REVISION HISTORY
3/08—Rev. G to Rev. H
Changes to Features .......................................................................... 1
Changes to Figure 1 .......................................................................... 1
Deleted Package Option Parameter ............................................... 4
Inserted ESD Caution ...................................................................... 5
Changes to Figure 2, Figure 3, and Figure 7.................................. 6
Changes to Figure 11 ........................................................................ 7
Changes to Figure 17 ........................................................................ 8
Changes to Figure 41 ...................................................................... 14
7/07—Rev. F to Rev. G
Changes to Figure 45 ...................................................................... 16
Changes to Temperature Compensated pH Probe
Amplifier Section ............................................................................ 17
Changes to Figure 46 ...................................................................... 17
Changes to Ordering Guide .......................................................... 18
5/06—Rev. E to Rev. F
Removed ESD Caution ..................................................................... 5
8/05—Rev. D to Rev. E
Change to Figure 22 .......................................................................... 9
5/04—Rev. C to Rev. D
Updated Format .................................................................. Universal
Changes to Features .......................................................................... 1
Updated Outline Dimensions ....................................................... 18
Added Ordering Guide .................................................................. 18
10/02—Rev. B to Rev. C
Deleted Product Highlights #5 ........................................................ 1
Edits to Specifications ....................................................................... 3
Deleted Metallization Photograph .................................................. 3
Updated Outline Dimensions ....................................................... 13
7/02—Rev. A to Rev. B
Edits to Specifications ....................................................................... 2