link to page 1 link to page 1 link to page 1 link to page 1 link to page 3 link to page 3 link to page 6 link to page 7 link to page 7 link to page 8 link to page 10 link to page 13 link to page 14 link to page 14 link to page 14 link to page 14 link to page 15 link to page 16 link to page 16 link to page 17 link to page 17 link to page 18 link to page 19 link to page 20 link to page 21 link to page 22 link to page 23 link to page 24 link to page 25 link to page 26 link to page 26 link to page 26 link to page 28 link to page 28 AD7985Data SheetTABLE OF CONTENTS Features .. 1 Analog Inputs ... 15 Applications ... 1 Driver Amplifier Choice ... 15 Application Diagram .. 1 Voltage Reference Input .. 16 General Description ... 1 Power Supply ... 16 Revision History ... 2 Digital Interface .. 17 Specifications ... 3 Data Reading Options ... 18 Timing Specifications .. 5 CS Mode, 3-Wire Without Busy Indicator ... 19 Absolute Maximum Ratings .. 6 CS Mode, 3-Wire with Busy Indicator .. 20 ESD Caution .. 6 CS Mode, 4-Wire Without Busy Indicator ... 21 Pin Configuration and Function Descriptions ... 7 CS Mode, 4-Wire with Busy Indicator .. 22 Typical Performance Characteristics ... 9 Chain Mode Without Busy Indicator .. 23 Terminology .. 12 Chain Mode with Busy Indicator ... 24 Theory of Operation .. 13 Applications Information .. 25 Circuit Information .. 13 Layout .. 25 Converter Operation .. 13 Evaluating the AD7985 Performance .. 25 Conversion Modes of Operation .. 13 Outline Dimensions ... 27 Typical Connection Diagram ... 14 Ordering Guide .. 27 REVISION HISTORY3/16—Rev. B to Rev. C7/14—Rev. A to Rev. B Changes to Table 1 .. 1 Added Patent Endnote .. 1 Change to Endnote 3, Table 1 ... 3 Changes to Figure 21 .. 13 Change to Signal-to-Noise-and-Distortion Ratio Parameter, Changes to Data Reading Options Section ... 18 Table 2 .. 3 Updated Outline Dimensions ... 27 Deleted Endnote 4, Table 2 .. 3 Changes to Figure 4 .. 7 8/10—Rev. 0 to Rev. A Changes to Figure 23 .. 14 Change to Table 4, Conversion Time: CNV Rising Edge Changes to Driver Amplifier Choice Section ... 15 to Data Available .. 5 Change to Reference Decoupling Section ... 16 Changes to Reading During Conversion, Fast Host (Turbo or 9/09—Revision 0: Initial Version Normal Mode) Section and Split-Reading, Any Speed Host (Turbo or Normal Mode) Section .. 18 Changes to Figure 31 .. 21 Updated Outline Dimensions ... 27 Changes to Ordering Guide .. 27 Rev. C | Page 2 of 28 Document Outline FEATURES APPLICATIONS APPLICATION DIAGRAM GENERAL DESCRIPTION REVISION HISTORY SPECIFICATIONS TIMING SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TERMINOLOGY THEORY OF OPERATION CIRCUIT INFORMATION CONVERTER OPERATION CONVERSION MODES OF OPERATION Transfer Functions TYPICAL CONNECTION DIAGRAM ANALOG INPUTS DRIVER AMPLIFIER CHOICE VOLTAGE REFERENCE INPUT Internal Reference, REF = 4.096 V (PDREF Low) External 1.2 V Reference and Internal Buffer (PDREF High) External Reference (PDREF High, REFIN Low) Reference Decoupling POWER SUPPLY DIGITAL INTERFACE DATA READING OPTIONS Reading During Conversion, Fast Host (Turbo or Normal Mode) Split-Reading, Any Speed Host (Turbo or Normal Mode) Reading During Acquisition, Any Speed Host (Turbo or Normal Mode) /CS MODE, 3-WIRE WITHOUT BUSY INDICATOR /CS MODE, 3-WIRE WITH BUSY INDICATOR /CS MODE, 4-WIRE WITHOUT BUSY INDICATOR /CS MODE, 4-WIRE WITH BUSY INDICATOR CHAIN MODE WITHOUT BUSY INDICATOR CHAIN MODE WITH BUSY INDICATOR APPLICATIONS INFORMATION LAYOUT EVALUATING THE AD7985 PERFORMANCE OUTLINE DIMENSIONS ORDERING GUIDE