Datasheet AD7794, AD7795 (Analog Devices) - 6

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AD7794/AD7795 Parameter
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AD7794/AD7795 Unit Test Conditions/Comments
BIAS VOLTAGE GENERATOR VBIAS AVDD/2 V nom VBIAS Generator Start-Up Time ms/nF typ Dependent on the capacitance connected to AIN; See Figure 11 TEMPERATURE SENSOR Accuracy ±2 °C typ Applies if user calibrates the temperature sensor Sensitivity 0.81 mV/°C typ LOW-SIDE POWER SWITCH RON 7 Ω max AVDD = 5 V 9 Ω max AVDD = 3 V Allowable Current2 30 mA max Continuous current DIGITAL OUTPUTS (P1 and P2) VOH, Output High Voltage2 AVDD − 0.6 V min AVDD = 3 V, ISOURCE = 100 μA VOL, Output Low Voltage2 0.4 V max AVDD = 3 V, ISINK = 100 μA VOH, Output High Voltage2 4 V min AVDD = 5 V, ISOURCE = 200 μA VOL, Output Low Voltage2 0.4 V max AVDD = 5 V, ISINK = 800 μA INTERNAL/EXTERNAL CLOCK Internal Clock Frequency2 64 ± 3% kHz min/max Duty Cycle 50:50 % typ External Clock Frequency 64 kHz nom A 128 kHz external clock can be used if the divide-by-2 function is used (Bit CLK1 = CLK0 = 1) Duty Cycle 45:55 to 55:45 % typ Applies for external 64 kHz clock, a 128 kHz clock can have a less stringent duty cycle LOGIC INPUTS CS2 VINL, Input Low Voltage 0.8 V max DVDD = 5 V 0.4 V max DVDD = 3 V VINH, Input High Voltage 2.0 V min DVDD = 3 V or 5 V SCLK (Schmitt-Triggered Input), CLK, and DIN2 AD7794B/AD7795B VT(+) 1.4/2 V min/max DVDD = 5 V VT(−) 0.8/1.7 V min/max DVDD = 5 V VT(+) to VT(−) 0.1/0.17 V min/max DVDD = 5 V VT(+) 0.9/2 V min/max DVDD = 3 V VT(−) 0.4/1.35 V min/max DVDD = 3 V VT(+) to VT(−) 0.06/0.13 V min/max DVDD = 3 V AD7794C VT(+) 1.35/2.05 V min/max DVDD = 5 V VT(−) 0.8/1.9 V min/max DVDD = 5 V VT(+) to VT(−) 0.1/0.19 V min/max DVDD = 5 V VT(+) 0.9/2 V min/max DVDD = 3 V VT(−) 0.4/1.35 V min/max DVDD = 3 V VT(+) to VT(−) 0.06/0.15 V min/max DVDD = 3 V Input Currents ±10 μA max VIN = DVDD or GND Input Capacitance 10 pF typ All digital inputs Rev. D | Page 6 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