Low Power, Low Noise Precision FET Op Amp Data Sheet AD795 FEATURES CONNECTION DIAGRAM Low power replacement for Burr-Brown NC 1 8 NC OPA111, OPA121 op amps IN 2 7 +V S Low noise +IN 3 6 OUTPUT 3.3 V p-p maximum, 0.1 Hz to 10 Hz V 4 5 NC S 11 nV/Hz maximum at 10 kHz AD795 0.6 fA/Hz at 1 kHz NC = NO CONNECT High dc accuracy Figure 1. 8-Lead SOIC (R) Package 500 V maximum offset voltage 10 V/C maximum drift 2 pA maximum input bias current Low power: 1.5 mA maximum supply current APPLICATIONS Low noise photodiode preamps CT scanners Precision l-to-V converters GENERAL DESCRIPTION The AD795 is a low noise, precision, FET input operational Furthermore, the AD795 features a guaranteed low input noise amplifier. It offers both the low voltage noise and low offset of 3.3 V p-p (0.1 Hz to 10 Hz) and a 11 nV/Hz maximum drift of a bipolar input op amp and the very low bias current of a noise level at 10 kHz. The AD795 has a fully specified and 14 FET-input device. The 10 common-mode impedance tested input offset voltage drift of only 10 V/C maximum. insures that input bias current is essentially independent of The AD795 is useful for many high input impedance, low noise common-mode voltage and supply voltage variations. applications. The AD795 is rated over the commercial tempera- The AD795 has both excellent dc performance and a guaranteed ture range of 0C to +70C. and tested maximum input voltage noise. It features 2 pA The AD795 is available in an 8-lead SOIC package. maximum input bias current and 500 V maximum offset 50 voltage, along with low supply current of 1.5 mA maximum. SAMPLE SIZE = 570 1k 40 30 100 20 10 10 0 5 4 3 2 1 0 1 2 3 4 5 INPUT OFFSET VOLTAGE DRIFT (V/C) 1 10 100 1k 10k Figure 3. Typical Distribution of Average Input Offset Voltage Drift FREQUENCY (Hz) Figure 2. Voltage Noise Spectral Density Rev. D 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 19922019 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. VOLTAGE NOISE SPECTRAL DENSITY (nV/ Hz) 00 84 5-00 2 PERCENTAGE OF UNITS 00845-001 00845-003AD795 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Offset Nulling ............................................................................. 13 Applications ....................................................................................... 1 AC Response with High Value Source and Feedback Resistance ........................................................................................................... 14 Connection Diagram ....................................................................... 1 Overload Issues ............................................................................... 15 General Description ......................................................................... 1 Input Protection ......................................................................... 15 Revision History ............................................................................... 2 Preamplifier Applications.......................................................... 16 Specifications ..................................................................................... 3 Minimizing Noise Contributions ............................................. 16 Absolute Maximum Ratings ............................................................ 5 Using a T Network ..................................................................... 17 Thermal Resistance ...................................................................... 5 A pH Probe Buffer Amplifier ................................................... 17 ESD Caution .................................................................................. 5 Outline Dimensions ....................................................................... 18 Typical Performance Characteristics ............................................. 6 Ordering Guide .......................................................................... 18 Minimizing Input Current ............................................................ 11 Circuit Board Notes ........................................................................ 12 REVISION HISTORY 8/2019Rev. C to Rev. D 10/2002Rev. A to Rev. B Changes to Table 1 ............................................................................ 3 Deleted Plastic Mini-DIP (N) Package ............................ Universal Changes to Ordering Guide .......................................................... 18 Edits to Features................................................................................. 1 Edits to Specifications ....................................................................... 2 12/2009Rev. B to Rev. C Edits to Absolute Maximum Ratings .............................................. 3 Changes to Features Section and General Description Section . 1 Edits to Ordering Guide ................................................................... 3 Changes to Input Bias Current Parameter, Table 1 ...................... 3 Edits to Circuit Board Notes ............................................................ 9 Changes to Table 2 ............................................................................ 5 Edits to Figure 31 ............................................................................... 9 Added Thermal Resistance Section ............................................... 5 Edits to Offset Nulling ................................................................... 10 Added Table 3 Renumbered Sequentially .................................... 5 Deleted Figure 34 ............................................................................ 10 Changes to Minimizing Input Current Section .......................... 11 Deleted Low Noise Op Amp Selection Tree ............................... 15 Changes to Circuit Board Notes Section and Figure 33 ............ 12 Updated Outline Dimensions ....................................................... 15 Changes to Input Protection Section ........................................... 15 Changes to Ordering Guide .......................................................... 18 10/1992Revision 0: Initial Version Rev. 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