Ultralow Input Bias Current Operational Amplifier Data Sheet AD549 FEATURES CONNECTION DIAGRAM GUARD PIN, Ultralow input bias current CONNECTED TO CASE 60 fA maximum (AD549L) OFFSET NULL 8 V+ 100 fA maximum (AD549K) 1 7 AD549 250 fA maximum (AD549J) INVERTING Input bias current guaranteed over the common-mode 2 6 OUTPUT INPUT voltage range 3 5 Low offset voltage NONINVERTING OFFSET 4 INPUT NULL 0.50 mV maximum (AD549K) V 1.00 mV maximum (AD549J) 10k Low offset drift 1 5 15 V/C maximum (AD549K) 4 15V 20 V/C maximum (AD549J) V TRIM OS Low power 700 A maximum supply current Figure 1. Low input voltage noise 4 V (typ) p-p over 0.1 Hz to 10 Hz MIL-STD-883B parts available APPLICATIONS Electrometer amplifier Photodiode preamp pH electrode buffer connected to a point at the same potential as the input terminals, GENERAL DESCRIPTION minimizing stray leakage to the case. The AD549 is available in The AD549 is a monolithic electrometer operational amplifier four performance grades. The J, K, and L versions are rated over with very low input bias current. Input offset voltage and input the commercial temperature range of 0C to +70C. The S grade offset voltage drift are laser trimmed for precision performance. is specified over the military temperature range of 55C to +125C The ultralow input current of the part is achieved with Topgate and is available processed to MIL-STD-883B, Rev. C. Extended JFET technology, a process development exclusive to Analog reliability plus screening is also available. Plus screening includes Devices, Inc. This technology allows fabrication of extremely 168 hour burn-in, as well as other environmental and physical low input current JFETs compatible with a standard junction tests derived from MIL-STD-883B, Rev. C. 15 isolated bipolar process. The 10 common-mode impedance, which results from the bootstrapped input stage, ensures that PRODUCT HIGHLIGHTS the input current is essentially independent of the common- 1. The AD549 input currents are specified, 100% tested, and mode voltage. guaranteed after the device is warmed up. They are guaran- The AD549 is suited for applications requiring very low input teed over the entire common-mode input voltage range. current and low input offset voltage. It excels as a preamp for a 2. The AD549 input offset voltage and drift are laser trimmed wide variety of current output transducers, such as photodiodes, to 0.50 mV and 15 V/C (AD549K), and to 1 mV and photomultiplier tubes, or oxygen sensors. The AD549 can also 20 V/C (AD549J). be used as a precision integrator or low droop sample-and-hold. 3. A maximum quiescent supply current of 700 A minimizes The AD549 is pin compatible with standard FET and electrometer heating effects on input current and offset voltage. op amps, allowing designers to upgrade the performance of present systems at little additional cost. 4. AC specifications include 1 MHz unity-gain bandwidth and 3 V/s slew rate. Settling time for a 10 V input step is The AD549 is available in a TO-99 hermetic package. The case 5 s to 0.01%. is connected to Pin 8, thus, the metal case can be independently Rev. K Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 20022015 Analog Devices, Inc. All rights reserved. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Technical Support www.analog.com Trademarks and registered trademarks are the property of their respective owners. 00511-001AD549 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Offset Nulling ............................................................................. 11 Applications ....................................................................................... 1 AC Response with High Value Source and Feedback Resistance .................................................................................... 12 Connection Diagram ....................................................................... 1 Common-Mode Input Voltage Overload ................................ 12 General Description ......................................................................... 1 Differential Input Voltage Overload ........................................ 13 Product Highlights ........................................................................... 1 Input Protection ......................................................................... 13 Revision History ............................................................................... 2 Sample-and-Difference Circuit to Measure Electrometer Specif icat ions ..................................................................................... 3 Leakage Currents ........................................................................ 13 Absolute Maximum Ratings ............................................................ 5 Photodiode Interface ................................................................. 14 ESD Caution .................................................................................. 5 Log Ratio Amplifier ................................................................... 15 Typical Performance Characteristics ............................................. 6 Temperature Compensated pH Probe Amplifier ................... 16 Functional Description .................................................................. 10 Outline Dimensions ....................................................................... 18 Minimizing Input Current ........................................................ 10 Ordering Guide .......................................................................... 18 Circuit Board Notes ................................................................... 10 REVISION HISTORY 2/15Rev. J to Rev. K 7/07Rev. F to Rev. G Updated Outline Dimensions ....................................................... 18 Changes to Figure 45 ...................................................................... 16 Changes to Temperature Compensated pH Probe 12/14Rev. I to Rev. J Amplifier Section............................................................................ 17 Added L Model ................................................................... Universal Changes to Figure 46 ...................................................................... 17 Changes to Features Section and Applications Section ............... 1 Changes to Ordering Guide .......................................................... 18 Changes to Table 1 ............................................................................ 3 5/06Rev. E to Rev. F Changes to Table 2 ............................................................................ 5 Changes to Log Ratio Amplifier Section ..................................... 15 Removed ESD Caution ..................................................................... 5 Changes to Temperature Compensated pH Probe 8/05Rev. D to Rev. E Amplifier Section ............................................................................ 16 Change to Figure 22 .......................................................................... 9 Changes to Ordering Guide .......................................................... 18 5/04Rev. C to Rev. D 6/14Rev. H to Rev. I Updated Format .................................................................. Universal Deleted L Model............................................................. Throughout Changes to Features .......................................................................... 1 Change to Features Section ............................................................. 1 Updated Outline Dimensions ....................................................... 18 Changes to Input Offset Voltage Parameter and Input Voltage Added Ordering Guide .................................................................. 18 Noise Parameter, Table 1 .................................................................. 3 Changes to Ordering Guide .......................................................... 18 10/02Rev. B to Rev. C 3/08Rev. G to Rev. H Deleted Product Highlights 5 ........................................................ 1 Edits to Specifications ....................................................................... 3 Changes to Features .......................................................................... 1 Deleted Metallization Photograph .................................................. 3 Changes to Figure 1 .......................................................................... 1 Updated Outline Dimensions ....................................................... 13 Deleted Package Option Parameter ............................................... 4 7/02Rev. A to Rev. B Inserted ESD Caution ...................................................................... 5 Changes to Figure 2, Figure 3, and Figure 7.................................. 6 Edits to Specifications ....................................................................... 2 Changes to Figure 11 ........................................................................ 7 Changes to Figure 17 ........................................................................ 8 Changes to Figure 41 ...................................................................... 14 Rev. K Page 2 of 18