Datasheet AD7738 (Analog Devices) - 9

AD7738 PIN FUNCTION DESCRIPTION (continued) Pin No. Mnemonic Pin Description
15 ADCIN(–) ADC Negative Input. In normal circuit configuration, this pin should be connected to the MUXOUT– pin. 16 ADCIN(+) ADC Positive Input. In normal circuit configuration, this pin should be connected to the MUXOUT+ pin. 21 REFIN(+) Positive Terminal of the Differential Reference Input. REFIN+ voltage potential can lie any where between AVDD and AGND. In normal circuit configuration, this pin should be connected to a 2.5 V reference voltage. 22 REFIN(–) Negative Terminal of the Differential Reference Input. REFIN– voltage potential can lie any where between AVDD and AGND. In normal circuit configuration, this pin should be connected to a 0 V reference voltage. 23 AGND Ground Reference Point for Analog Circuitry 24 RDY Logic Output. Used as a status output in both conversion mode and calibration mode. In conversion mode, a falling edge on this output indicates that either any channel or all channels have unread data available—according to the RDY function bit in the I/O Port register. In calibration mode, a falling edge on this output indicates that calibration is complete. See more details in Digital Interface Description section later in this data sheet. 25 DOUT Serial Data Output with serial data being read from the output shift register on the part. This output shift register can contain information from any AD7738 register depending on the address bits of the Communications register. 26 DIN Serial Data Input (Schmitt triggered) with serial data being written to the input shift register on the part. Data from this input shift register is transferred to any AD7738 register depending on the address bits of the Communications register. 27 DVDD Digital Supply Voltage, 3 V or 5 V Nominal 28 DGND Ground Reference Point for Digital Circuitry –8– REV. 0 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM SPECIFICATIONS TIMING SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ORDERING GUIDE PIN CONFIGURATION PIN FUNCTION DESCRIPTION PIN FUNCTION DESCRIPTION (continued) OUTPUT NOISE AND RESOLUTION SPECIFICATION CHOPPING ENABLED CHOPPING DISABLED Typical Performance Characteristics REGISTER DESCRIPTION Communications Register I/O Port Register Revision Register Test Register ADC Status Register Checksum Register ADC Zero Scale Calibration Register ADC Full-Scale Register Channel Data Registers Channel Zero-Scale Calibration Registers Channel Full-Scale Calibration Registers Channel Status Registers Channel Setup Registers Channel Conversion Time Registers Mode Register DIGITAL INTERFACE DESCRIPTION Hardware Reset Access the AD7738 Registers Single Conversion and Reading Data Dump Mode Continuous Conversion Mode Continuous Read (Continuous Conversion) Mode CIRCUIT DESCRIPTION Analog Front End Sigma-Delta ADC Chopping Multiplexer, Conversion, and Data Output Timing Frequency Response Analog Inputs Voltage Range Analog Inputs Extended Voltage Range Voltage Reference Inputs Reference Detect I/O Port CALIBRATION ADC Zero-Scale Self-Calibration Per Channel System Calibration OUTLINE DIMENSIONS