Datasheet AD7798, AD7799 (Analog Devices) - 4

link to page 5 link to page 5 link to page 5 link to page 5 link to page 5 link to page 5 link to page 5 link to page 5 link to page 5 link to page 5 link to page 5 link to page 5 link to page 5 link to page 5 link to page 5
AD7798/AD7799 Data Sheet Parameter AD7798B/AD7799B1 Unit Test Conditions/Comments
REFERENCE External REFIN Voltage 2.5 V nom REFIN = REFIN(+) − REFIN(−) Reference Voltage Range2 0.1 V min AVDD V max When VREF = AVDD, the differential input must be limited to (0.9 x VREF/gain) if the in-amp is active. Absolute REFIN Voltage Limits2 GND − 30 mV V min AVDD + 30 mV V max Average Reference Input Current 400 nA/V typ Average Reference Input Current Drift ±0.03 nA/V/°C typ Normal Mode Rejection Same as for analog inputs Common-Mode Rejection 100 dB typ Reference Detect Levels 0.3 V min 0.65 V max NOXREF bit active if VREF < 0.3 V 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) Output High Voltage, V 2 OH AVDD − 0.6 V min AVDD = 3 V, ISOURCE = 100 µA Output Low Voltage, V 2 OL 0.4 V max AVDD = 3 V, ISINK = 100 µA Output High Voltage, V 2 OH 4 V min AVDD = 5 V, ISOURCE = 200 µA Output Low Voltage, V 2 OL 0.4 V max AVDD = 5 V, ISINK = 800 µA INTERNAL CLOCK Frequency2 64 ± 3% kHz min/max LOGIC INPUTS CS2 Input Low Voltage, VINL 0.8 V max DVDD = 5 V 0.4 V max DVDD = 3 V Input High Voltage, VINH 2.0 V min DVDD = 3 V or 5 V SCLK and DIN (Schmitt-Triggered Input)2 VT(+) 1.4/2 V min/max DVDD = 5 V VT(–) 0.8/1.7 V min/max DVDD = 5 V VT(+) – 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(+) − VT(–) 0.06/0.13 V min/max DVDD = 3 V Input Currents ±10 µA max VIN = DVDD or GND Input Capacitance 10 pF typ All digital inputs LOGIC OUTPUTS Output High Voltage, V 2 OH DVDD − 0.6 V min DVDD = 3 V, ISOURCE = 100 µA Output Low Voltage, V 2 OL 0.4 V max DVDD = 3 V, ISINK = 100 µA Output High Voltage, V 2 OH 4 V min DVDD = 5 V, ISOURCE = 200 µA Output Low Voltage, V 2 OL 0.4 V max DVDD = 5 V, ISINK = 1.6 mA Floating-State Leakage Current ±10 µA max Floating-State Output Capacitance 10 pF typ Data Output Coding Offset binary Rev. B | Page 4 of 28 Document Outline Features Interface Applications Functional Block Diagram General Description Revision History Specifications Timing Characteristics Absolute Maximum Ratings ESD Caution Pin Configuration and Function Descriptions Output Noise and Resolution Specifications AD7798 AD7799 Typical Performance Characteristics On-Chip Registers Communication Register RS2, RS1, RS0 = 0, 0, 0 Status Register RS2, RS1, RS0 = 0, 0, 0; Power-On/Reset = 0x80 (AD7798)/0x88 (AD7799) 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(00) ID Register RS2, RS1, RS0 = 1, 0, 0; Power-On/Reset = 0xX8 (AD7798)/0xX9 (AD7799) IO Register RS2, RS1, RS0 = 1, 0, 1; Power-On/Reset = 0x00 Offset Register RS2, RS1, RS0 = 1, 1, 0; Power-On/Reset = 0x8000(AD7798)/0x800000 (AD7799) Full-Scale Register RS2, RS1, RS0 = 1, 1, 1; Power-On/Reset = 0x5XXX (AD7798)/0x5XXX00 (AD7799) 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 Reference Reference Detect Reset AVDD Monitor Calibration Grounding and Layout Applications Information Weigh Scales Outline Dimensions Ordering Guide