Datasheet AD7705, AD7706 (Analog Devices) - 2

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AD7705/AD7706 TABLE OF CONTENTS
Features .. 1 Reference Input... 23 General Description ... 1 Digital Filtering... 23 Functional Block Diagram .. 1 Analog Filtering.. 25 Revision History ... 3 Calibration... 25 Product Highlights ... 4 Theory of Operation .. 28 Specifications... 5 Clocking and Oscillator Circuit ... 28 Timing Characteristics .. 8 System Synchronization .. 28 Absolute Maximum Ratings.. 9 RESET Input ... 29 ESD Caution.. 9 Standby Mode ... 29 Pin Configurations and Function Descriptions ... 10 Accuracy .. 29 Output Noise (5 V Operation).. 12 Drift Considerations .. 29 Output Noise (3 V Operation).. 13 Power Supplies .. 30 Typical Performance Characteristics ... 14 Supply Current.. 30 On-Chip Registers .. 16 Grounding and Layout .. 30 Communication Register (RS2, RS1, RS0 = 0, 0, 0)... 16 Evaluating the Performance.. 31 Setup Register (RS2, RS1, RS0 = 0, 0, 1); Power-On/Reset Digital Interface.. 31 Status: 01 Hexadecimal .. 17 Configuring the AD7705/AD7706 .. 33 Clock Register (RS2, RS1, RS0 = 0, 1, 0); Power-On/Reset Status: 05 Hexadecimal .. 19 Microcomputer/Microprocessor Interfacing ... 34 Data Register (RS2, RS1, RS0 = 0, 1, 1) ... 20 Code For Setting Up the AD7705/AD7706.. 35 Test Register (RS2, RS1, RS0 = 1, 0, 0); Power-On/Reset Applications... 38 Status: 00 Hexadecimal .. 20 Pressure Measurement... 38 Zero-Scale Calibration Register (RS2, RS1, RS0 = 1, 1, 0); Temperature Measurement ... 39 Power-On/Reset Status: 1F4000 Hexadecimal ... 20 Smart Transmitters... 40 Full-Scale Calibration Register (RS2, RS1, RS0 = 1, 1, 1); Power-On/Reset Status: 5761AB HexaDecimal... 20 Battery Monitoring .. 41 Circuit Description... 21 Outline Dimensions ... 42 Analog Input ... 22 Ordering Guide .. 43 Bipolar/Unipolar Input .. 22 Rev. C | Page 2 of 44 Document Outline FEATURES GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM REVISION HISTORY PRODUCT HIGHLIGHTS SPECIFICATIONS TIMING CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS OUTPUT NOISE (5 V OPERATION) OUTPUT NOISE (3 V OPERATION) TYPICAL PERFORMANCE CHARACTERISTICS ON-CHIP REGISTERS COMMUNICATION REGISTER (RS2, RS1, RS0 = 0, 0, 0) SETUP REGISTER (RS2, RS1, RS0 = 0, 0, 1); POWER-ON/RESET STATUS: 01 HEXADECIMAL CLOCK REGISTER (RS2, RS1, RS0 = 0, 1, 0); POWER-ON/RESET STATUS: 05 HEXADECIMAL DATA REGISTER (RS2, RS1, RS0 = 0, 1, 1) TEST REGISTER (RS2, RS1, RS0 = 1, 0, 0); POWER-ON/RESET STATUS: 00 HEXADECIMAL ZERO-SCALE CALIBRATION REGISTER (RS2, RS1, RS0 = 1, 1, 0); POWER-ON/RESET STATUS: 1F4000 HEXADECIMAL FULL-SCALE CALIBRATION REGISTER (RS2, RS1, RS0 = 1, 1, 1); POWER-ON/RESET STATUS: 5761AB HEXADECIMAL Calibration Sequences CIRCUIT DESCRIPTION ANALOG INPUT Ranges Sample Rate BIPOLAR/UNIPOLAR INPUT REFERENCE INPUT DIGITAL FILTERING Filter Characteristics Postfiltering ANALOG FILTERING CALIBRATION Self-Calibration System Calibration Span and Offset Limits Power-Up and Calibration THEORY OF OPERATION CLOCKING AND OSCILLATOR CIRCUIT SYSTEM SYNCHRONIZATION RESET INPUT STANDBY MODE ACCURACY DRIFT CONSIDERATIONS POWER SUPPLIES SUPPLY CURRENT GROUNDING AND LAYOUT EVALUATING THE PERFORMANCE DIGITAL INTERFACE CONFIGURING THE AD7705/AD7706 MICROCOMPUTER/MICROPROCESSOR INTERFACING AD7705/AD7706-to-68HC11 Interface AD7705/AD7706-to-8051 Interface AD7705/AD7706-to-ADSP-2103/ADSP-2105 Interface CODE FOR SETTING UP THE AD7705/AD7706 C Code for Interfacing AD7705 to 68HC11 APPLICATIONS PRESSURE MEASUREMENT TEMPERATURE MEASUREMENT SMART TRANSMITTERS BATTERY MONITORING OUTLINE DIMENSIONS ORDERING GUIDE