link to page 1 link to page 1 link to page 1 link to page 1 link to page 3 link to page 4 link to page 6 link to page 7 link to page 7 link to page 7 link to page 8 link to page 9 link to page 11 link to page 12 link to page 12 link to page 13 link to page 13 link to page 13 link to page 13 link to page 14 link to page 15 link to page 15 link to page 15 link to page 15 link to page 16 link to page 17 link to page 12 link to page 13 link to page 13 link to page 17 AD7781TABLE OF CONTENTS Features .. 1 Gain .. 11 Applications ... 1 Power-Down/Reset (PDRST) ... 12 Functional Block Diagram .. 1 Analog Input Channel ... 12 General Description ... 1 Bipolar Configuration .. 12 Revision History ... 2 Data Output Coding .. 12 Specifications ... 3 Reference ... 12 Timing Characteristics .. 5 Bridge Power-Down Switch .. 12 Absolute Maximum Ratings .. 6 Digital Interface .. 13 Thermal Resistance .. 6 Applications Information .. 14 ESD Caution .. 6 Weigh Scales .. 14 Pin Configurations and Function Descriptions ... 7 AD7781 Performance in a Weigh Scale System ... 14 Typical Performance Characteristics ... 8 EMI Recommendations ... 14 Output Noise and Resolution.. 10 Grounding and Layout .. 15 Theory of Operation .. 11 Outline Dimensions ... 16 Filter, Data Rate, and Settling Time ... 11 Ordering Guide .. 16 REVISION HISTORY5/09—Revision 0: Initial Version Rev. 0 | Page 2 of 16 Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS TIMING CHARACTERISTICS Circuit and Timing Diagrams ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS OUTPUT NOISE AND RESOLUTION THEORY OF OPERATION FILTER, DATA RATE, AND SETTLING TIME GAIN POWER-DOWN/RESET (PDRST) ANALOG INPUT CHANNEL BIPOLAR CONFIGURATION DATA OUTPUT CODING REFERENCE BRIDGE POWER-DOWN SWITCH DIGITAL INTERFACE APPLICATIONS INFORMATION WEIGH SCALES AD7781 PERFORMANCE IN A WEIGH SCALE SYSTEM EMI RECOMMENDATIONS GROUNDING AND LAYOUT OUTLINE DIMENSIONS ORDERING GUIDE