Precision Instrumentation Amplifier with Signal Processing Amplifiers AD8295 FEATURES CONNECTION DIAGRAM +V OUT A2 +IN A2 IN S Saves board space 16 15 14 13 Includes precision in-amp, 2 op amps, and AD8295 IN 1 12 A2 OUT 2 matched resistors A2 4 mm 4 mm LFCSP No heat slug for more routing room R 2 11 A1 +IN G Differential output fully specified IA In-amp specifications R 3 10 A1 R1 G Gain set with 1 external resistor (gain range: 1 to 1000) R1 A1 20k Input voltage noise: 8 nV/Hz maximum at 1 kHz R2 +IN 4 9 A1 IN CMRR (G = 1): 90 dB minimum 20k Input bias current: 0.8 nA maximum 5 6 7 8 V REF A1 OUT A1 R2 S 3 dB bandwidth (G = 1): 1.2 MHz Figure 1. Slew rate: 2 V/s Wide power supply range: 2.3 V to 18 V 1 ppm/C, 0.03% resistor matching 1 Table 1. Instrumentation Amplifiers by Category APPLICATIONS General- Zero Military Low High Speed Industrial process controls Purpose Drift Grade Power PGA Wheatstone bridges AD8220 AD8231 AD620 AD8236 AD8250 Precision data acquisition systems AD8221 AD8553 AD621 AD627 AD8251 Medical instrumentation AD8222 AD8555 AD524 AD623 AD8253 Strain gages AD8224 AD8556 AD526 AD8223 Transducer interfaces AD8228 AD8557 AD624 AD8226 Differential output AD8295 AD8293 AD8227 1 See www.analog.com for the latest selection of instrumentation amplifiers. The AD8295 includes a high performance, programmable gain GENERAL DESCRIPTION instrumentation amplifier. Gain is set from 1 to 1000 with a The AD8295 contains all the components necessary for a single resistor. The low noise and excellent common-mode precision instrumentation amplifier front end in one small rejection of the AD8295 enable the part to easily detect small 4 mm 4 mm package. It contains a high performance signals even in the presence of large common-mode interference. instrumentation amplifier, two general-purpose operational For a similar instrumentation amplifier without the associated amplifiers, and two precisely matched 20 k resistors. signal conditioning circuitry, see the AD8221 or AD8222 data The AD8295 is designed to make PCB routing easy and sheet. efficient. The AD8295 components are arranged in a logical The AD8295 operates on both single and dual supplies and is way so that typical application circuits have short routes and well suited for applications where 10 V input voltages are few vias. Unlike most chip scale packages, the AD8295 does not encountered. Performance is specified over the entire industrial have an exposed metal pad on the back of the part, which frees temperature range of 40C to +85C for all grades. The additional space for routing and vias. The logical pin arrange- AD8295 is operational from 40C to +125C see the Typical ment and routing freedom enable the AD8295 to offer simple Performance Characteristics section for expected operation up pin-strapped solutions for complex systems in the equivalent to 125C. board space of a typical MSOP package. Rev. A 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 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781.461.3113 20082009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 07343-001AD8295 TABLE OF CONTENTS Features .............................................................................................. 1 System .......................................................................................... 18 Applications ....................................................................................... 1 Theory of Operation ...................................................................... 19 Connection Diagram ....................................................................... 1 Uncommitted Op Amps ............................................................ 19 General Description ......................................................................... 1 Instrumentation Amplifier........................................................ 19 Revision History ............................................................................... 2 Layout .......................................................................................... 20 Specif icat ions ..................................................................................... 3 Input Protection ......................................................................... 21 Instrumentation Amplifier Specifications, Single-Ended and Input Bias Current Return Path ............................................... 21 Differential Output Configurations ........................................... 3 RF Interference ........................................................................... 21 Op Amp Specifications ................................................................ 5 Differential Output .................................................................... 22 Internal Resistor Network ........................................................... 6 Applications Information .............................................................. 23 Power and Temperature Specifications ..................................... 6 Creating a Reference Voltage at Midscale ............................... 23 Absolute Maximum Ratings ............................................................ 7 High Accuracy G = 1 Configuration with Low-Pass Filter .. 23 Thermal Characteristics .............................................................. 7 Two-Pole Sallen-Key Filter ........................................................ 24 ESD Caution .................................................................................. 7 AC-Coupled Instrumentation Amplifier ................................ 24 Pin Configuration and Function Descriptions ............................. 8 Driving Differential ADCs ........................................................ 25 Typical Performance Characteristics ............................................. 9 Outline Dimensions ....................................................................... 26 In-Amp .......................................................................................... 9 Ordering Guide .......................................................................... 26 Op Amps ...................................................................................... 16 REVISION HISTORY 6/09Rev. 0 to Rev. A Changes to General Description Section ...................................... 1 Changes to Table 1 ............................................................................ 1 Changes to Table 3 ............................................................................ 5 Added Figure 42, Figure 45, and Figure 46 Renumbered Sequentially ..................................................................................... 16 Added Figure 49 .............................................................................. 17 Changes to Figure 51 and Figure 52 ............................................. 17 Added Figure 53 and Figure 54..................................................... 18 Changes to Figure 59 ...................................................................... 19 Added Routing and Vias Section .................................................. 20 Updated Outline Dimensions ....................................................... 26 10/08Revision 0: Initial Version Rev. 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