AD7944Data SheetTable 3. ParameterTest Conditions/CommentsMinTypMaxUnit INTERNAL REFERENCE PDREF is low Output Voltage TA = 25°C 4.081 4.096 4.111 V Temperature Drift −40°C to +85°C ±10 ppm/°C Line Regulation AVDD = 2.5 V ± 5% ±50 ppm/V Turn-On Settling Time CREF = 10 μF, CREFIN = 0.1 μF 40 ms REFIN Output Voltage REFIN at 25°C 1.2 V REFIN Output Resistance 6 kΩ EXTERNAL REFERENCE PDREF is high, REFIN is low Voltage Range 2.4 5.1 V Current Drain 500 µA REFERENCE BUFFER REFIN Input Voltage 1.2 V REFIN Input Current 160 µA DIGITAL INPUTS Logic Levels VIL −0.3 +0.1 × VIO V VIH 0.9 × VIO VIO + 0.3 V IIL −1 +1 µA IIH −1 +1 µA DIGITAL OUTPUTS Data Format Serial 14 bits, straight binary Pipeline Delay Conversion results available immediately after completed conversion VOL ISINK = +500 µA 0.4 V VOH ISOURCE = −500 µA VIO − 0.3 V POWER SUPPLIES AVDD, DVDD 2.375 2.5 2.625 V BVDD 4.75 5.0 5.25 V VIO Specified performance 1.8 2.5 2.7 V Standby Current1, 2 AVDD = DVDD = VIO = 2.5 V 1.0 µA Power Dissipation With Internal Reference 2.5 MSPS throughput 28 33 mW 2.0 MSPS throughput 25 30 mW With External Reference 2.5 MSPS throughput 15.5 17 mW 2.0 MSPS throughput 12 13 mW TEMPERATURE RANGE3 Specified Performance TMIN to TMAX −40 +85 °C 1 With all digital inputs forced to VIO or GND as required. 2 During acquisition phase. 3 Contact an Analog Devices, Inc., sales representative for the extended temperature range. Rev. C | Page 4 of 28 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION APPLICATION DIAGRAM TABLE OF CONTENTS 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 APPLICATION 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 AD7944 PERFORMANCE OUTLINE DIMENSIONS ORDERING GUIDE