Low Voltage, Low Power, a Factory-Calibrated 16-/24-Bit Dual - ADC AD7719 FEATURES APPLICATIONS HIGH RESOLUTION - ADCs Sensor Measurement 2 Independent ADCs (16- and 24-Bit Resolution) Temperature Measurement Factory-Calibrated (Field Calibration Not Required) Pressure Measurement Output Settles in 1 Conversion Cycle (Single Weigh Scales Conversion Mode) Portable Instrumentation Programmable Gain Front End 4 to 20 mA Transmitters Simultaneous Sampling and Conversion of 2 Signal Sources Separate Reference Inputs for Each Channel GENERAL DESCRIPTION Simultaneous 50 Hz and 60 Hz Rejection at 20 Hz The AD7719 is a complete analog front end for low frequency Update Rate measurement applications. It contains two high resolution - ADCs, switchable matched excitation current sources, low-side ISOURCE Select power switches, digital I/O port, and temperature sensor. The 24-Bit No Missing CodesMain ADC 24-bit main channel with PGA accepts fully differential, unipolar, 13-Bit p-p Resolution 20 Hz, 20 mV Range and bipolar input signal ranges from 1.024 REFIN1/128 to 18-Bit p-p Resolution 20 Hz, 2.56 V Range 1.024 REFIN1. Signals can be converted directly from a trans- INTERFACE ducer without the need for signal conditioning. The 16-bit auxiliary 3-Wire Serial channel has an input signal range of REFIN2 or REFIN2/2. SPI , QSPI, MICROWIRE, and DSP Compatible The device operates from a 32 kHz crystal with an on-chip Schmitt Trigger on SCLK PLL generating the required internal operating frequency. The POWER output data rate from the part is software programmable. The Specified for Single 3 V and 5 V Operation peak-to-peak resolution from the part varies with the programmed Normal: 1.5 mA Typ 3 V gain and output data rate. Power-Down: 10 A (32 kHz Crystal Running) The part operates from a single 3 V or 5 V supply. When oper- ON-CHIP FUNCTIONS ating from 3 V supplies, the power dissipation for the part is Rail-Rail Input Buffer and PGA 4.5 mW with both ADCs enabled and 2.85 mW with only the 4-Bit Digital I/O Port main ADC enabled in unbuffered mode. The AD7719 is housed On-Chip Temperature Sensor in 28-lead SOIC and TSSOP packages. Dual Switchable Excitation Current Sources Low-Side Power Switches Reference Detect Circuit FUNCTIONAL BLOCK DIAGRAM DV REFIN1(+) REFIN1() XTAL1 XTAL2 DD DGND AV DD REFERENCE IEXC1 OSC. AND IEXC2 DETECT AD7719 200 A PLL 200 A IOUT1 DOUT IOUT2 SERIAL DIN AV MAIN CHANNEL INTERFACE DD AIN1 SCLK 24-BIT - ADC AND AIN2 CS CONTROL MUX1 BUF PGA RDY AIN3 LOGIC RESET AIN4 AV DD AGND I/O PORT AIN5 AUXILIARY CHANNEL MUX2MUX AIN6 16-BIT - ADC TEMP SENSOR AV AGND REFIN2 PWRGND P1/SW1 P2/SW2 P3 P4 DD REV. A Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. may result from its use. No license is granted by implication or otherwise Tel: 781/329-4700 www.analog.com under any patent or patent rights of Analog Devices. Trademarks and Fax: 781/326-8703 2003 Analog Devices, Inc. All rights reserved. registered trademarks are the property of their respective companies.AD7719 TABLE OF CONTENTS FEATURES . 1 Main ADC Offset Calibration Coefficient Registers (OF0): GENERAL DESCRIPTION . 1 (A3, A2, A1, A0 = 1, 0, 0, 0 SPECIFICATIONS . 3 Power-On Reset = 0x80 0000) . 26 ABSOLUTE MAXIMUM RATINGS . 6 Aux ADC Offset Calibration Coefficient Registers (OF1): ORDERING GUIDE 6 (A3, A2, A1, A0 = 1, 0, 0, 1 TIMING CHARACTERISTICS . 7 Power-On Reset = 0x8000) . 26 DIGITAL INTERFACE 8 Main ADC Gain Calibration Coefficient Registers (GNO): PIN CONFIGURATION . 9 (A3, A2, A1, A0 = 1, 0, 1, 0 PIN FUNCTION DESCRIPTIONS 9 Power-On Reset = 0x5X XXX5) . 26 TYPICAL PERFORMANCE CHARACTERISTICS 11 Aux ADC Gain Calibration Coefficient Registers (GN1): DUAL-CHANNEL ADC CIRCUIT INFORMATION . 12 (A3, A2, A1, A0 = 1, 0, 1, 1 Overview . 12 Power-On Reset = 0x59XX) . 26 Main Channel . 12 ID Register (ID): (A3, A2, A1, A0 = 1, 1, 1, 1 Auxiliary Channel 12 Power-On Reset = 0x0X) . 26 Both Channels . 13 User Nonprogrammable Test Registers 26 MAIN AND AUXILIARY ADC NOISE CONFIGURING THE AD7719 . 27 PERFORMANCE 14 MICROCOMPUTER/MICROPROCESSOR ON-CHIP REGISTERS . 16 INTERFACING . 27 Communications Register AD7719-to-68HC11 Interface . 29 (A3, A2, A1, A0 = 0, 0, 0, 0) 19 AD7719-to-8051 Interface 29 Status Register (A3, A2, A1, A0 = 0, 0, 0, 0 AD7719-to-ADSP-2103/ADSP-2105 Interface 30 Power-On Reset = 0x00) . 20 CIRCUIT DESCRIPTION 30 Mode Register (A3, A2, A1, A0 = 0, 0, 0, 1 Analog Input Channels 31 Power-On Reset = 0x00) . 21 Programmable Gain Amplifier . 32 Operating Characteristics when Addressing the Bipolar/Unipolar Configuration 32 Mode and Control Registers . 22 Data Output Coding 33 Main ADC Control Register (AD0CON): Burnout Currents . 33 (A3, A2, A1, A0 = 0, 0, 1, 0 Excitation Currents . 33 Power-On Reset = 0x07) . 22 Crystal Oscillator . 33 Aux ADC Control Registers (AD1CON): Reference Input 33 (A3, A2, A1, A0 = 0, 0, 1, 1 Reference Detect . 34 Power-On Reset = 0x01) . 23 Reset Input . 34 Filter Register (A3, A2, A1, A0 = 0, 1, 0, 0 Power-Down Mode . 34 Power-On Reset = 0x45) . 24 Idle Mode 34 I/O and Current Source Control Register (IOCON): ADC Disable Mode . 34 (A3, A2, A1, A0 = 0, 1, 1, 1 Calibration 34 Power-On Reset = 0x0000) . 24 Grounding and Layout . 35 Main ADC Data Result Registers (DATA0): APPLICATIONS 35 (A3, A2, A1, A0 = 0, 1, 0, 1 Pressure Measurement . 36 Power-On Reset = 0x00 0000) . 26 Temperature Measurement . 36 Aux ADC Data Result Registers (DATA1): 3-Wire RTD Configurations 37 (A3, A2, A1, A0 = 0, 1, 1, 0 Smart Transmitters . 38 Power-On Reset = 0x0000) . 26 OUTLINE DIMENSIONS . 39 REVISION HISTORY 40 2 REV. 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