Datasheet AD7794, AD7795 (Analog Devices) - 4

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AD7794/AD7795 Parameter
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AD7794/AD7795 Unit Test Conditions/Comments
Common-Mode Rejection AD7794B/AD7795B @ DC 100 dB min AIN = 1 V/gain, gain ≥ 4 @ 50 Hz, 60 Hz2 100 dB min 50 ± 1 Hz, 60 ± 1 Hz, FS[3:0] = 1010 @ 50 Hz, 60 Hz2 100 dB min 50 ± 1 Hz, FS[3:0] = 1001; 60 ± 1 Hz, FS[3:0] = 1000 AD7794C @ DC 97 dB min AIN = 1 V/gain, gain ≥ 4 @ 50 Hz, 60 Hz2 97 dB min 50 ± 1 Hz, 60 ± 1 Hz, FS[3:0] = 1010 @ 50 Hz, 60 Hz2 97 dB min 50 ± 1 Hz, FS[3:0] = 1001; 60 ± 1 Hz, FS[3:0] = 1000
CHOP DISABLED
Output Update Rate 4.17 to 470 Hz nom Settling time = 1/output update rate No Missing Codes2 AD7794 24 Bits min fADC ≤ 123 Hz AD7795 16 Bits min Resolution See the RMS Noise and Resolution Specifications section RMS Noise and Update Rates See the RMS Noise and Resolution Specifications section Integral Nonlinearity ±15 ppm of FSR max Offset Error3 ±100/gain μV typ Without calibration Offset Error Drift vs. Temperature4 ±100/gain nV/°C typ Gain = 1 to 16 10 nV/°C typ Gain = 32 to 128 Full-Scale Error3, 5 ±10 μV typ Gain Drift vs. Temperature4 ±1 ppm/°C typ Gain = 1 to 16, external reference ±3 ppm/°C typ Gain = 32 to 128, external reference Power Supply Rejection 100 dB typ AIN = 1 V/gain, gain ≥ 4, external reference ANALOG INPUTS Differential Input Voltage Ranges ±VREF/gain V nom VREF = REFIN(+) − REFIN(−), or internal reference, gain = 1 to 128 Absolute AIN Voltage Limits2 Unbuffered Mode GND − 30 mV V min Gain = 1 or 2 AVDD + 30 mV V max Buffered Mode GND + 100 mV V min Gain = 1 or 2 AVDD − 100 mV V max In-Amp Active GND + 300 mV V min Gain = 4 to 128 AVDD − 1.1 V max Common-Mode Voltage, VCM 0.2 + (gain/2 × (AIN(+) − V min AMP − CM = 1, VCM = (AIN(+) + AIN(–))/2, gain = 4 to 128 AIN(−))) AVDD − 0.2 − (gain/2 × V max (AIN(+) − AIN(−))) Analog Input Current Buffered Mode or In-Amp Active Average Input Current2 AD7794B/AD7795B ±1 nA max Gain = 1 or 2 ±250 pA max Gain = 4 to 128 ±1 nA max AIN6(+)/AIN6(−) AD7794C ±3 nA max Gain = 1 or 2 ±2 nA max Gain = 4 to 128 ±3 nA max AIN6(+)/AIN6(−) Average Input Current Drift ±2 pA/°C typ Unbuffered Mode Gain = 1 or 2 Average Input Current ±400 nA/V typ Input current varies with input voltage Average Input Current Drift ±50 pA/V/°C typ Rev. D | Page 4 of 36 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS TIMING CHARACTERISTICS TIMING DIAGRAMS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS RMS NOISE AND RESOLUTION SPECIFICATIONS CHOP ENABLED External Reference Internal Reference CHOP DISABLED TYPICAL PERFORMANCE CHARACTERISTICS ON-CHIP REGISTERS COMMUNICATIONS REGISTER RS2, RS1, RS0 = 0, 0, 0 STATUS REGISTER RS2, RS1, RS0 = 0, 0, 0; Power-On/Reset = 0x80 (AD7795)/0x88 (AD7794) MODE REGISTER RS2, RS1, RS0 = 0, 0, 1; Power-On/Reset = 0x000A CONFIGURATION REGISTER RS2, RS1, RS0 = 0, 1, 0; Power-On/Reset = 0x0710 DATA REGISTER RS2, RS1, RS0 = 0, 1, 1; Power-On/Reset = 0x0000(AD7795), 0x000000 (AD7794) ID REGISTER RS2, RS1, RS0 = 1, 0, 0; Power-On/Reset = 0xXF IO REGISTER RS2, RS1, RS0 = 1, 0, 1; Power-On/Reset = 0x00 OFFSET REGISTER RS2, RS1, RS0 = 1, 1, 0; Power-On/Reset = 0x8000 (AD7795), 0x800000 (AD7794)) FULL-SCALE REGISTER RS2, RS1, RS0 = 1, 1, 1; Power-On/Reset = 0x5XXX (AD7795), 0x5XXX00 (AD7794) ADC CIRCUIT INFORMATION OVERVIEW DIGITAL INTERFACE Single Conversion Mode Continuous Conversion Mode Continuous Read CIRCUIT DESCRIPTION ANALOG INPUT CHANNEL INSTRUMENTATION AMPLIFIER BIPOLAR/UNIPOLAR CONFIGURATION DATA OUTPUT CODING BURNOUT CURRENTS EXCITATION CURRENTS BIAS VOLTAGE GENERATOR REFERENCE REFERENCE DETECT RESET AVDD MONITOR CALIBRATION GROUNDING AND LAYOUT APPLICATIONS INFORMATION FLOWMETER OUTLINE DIMENSIONS ORDERING GUIDE