Datasheet AD7734 (Analog Devices)

4-Channel, ±10 V Input Range, High Throughput, 24-Bit Sigma-Delta ADC Data Sheet AD7734 FEATURES FUNCTIONAL BLOCK DIAGRAM High resolution analog-to-digital converter (ADC) REFIN(–) REFIN(+) 24 bits no missing codes AIN0 REFERENCE ±0.0025% nonlinearity DETECT Optimized for fast channel switching AIN1 18-bit p-p resolution (21 bits effective) at 500 Hz BUFFER 16-bit p-p resolution (19 bits effective) at 2 kHz MUX 24-BIT AIN2 Σ-∆ ADC 14-bit p-p resolution (18 bits effective) at 15 kHz On-chip per channel system calibration AIN3 4 single-ended analog inputs AD7734 Input ranges +5 V, ±5 V, +10 V, ±10 V BIASHI Overvoltage tolerant BIASLO Up to ±16.5 V not affecting adjacent channel SCLK DOUT Up to ±50 V absolute maximum CALIBRATION SERIAL CIRCUITRY INTERFACE DIN 3-wire serial interface CS SPI, QSPI™, MICROWIRE, and DSP compatible Schmitt trigger on logic inputs P0 RDY Single-supply operation CLOCK CONTROL I/O PORT GENERATOR LOGIC SYNC/P1 RESET 5 V analog supply
01
3 V or 5 V digital supply
0 71-
AGND AV MCLKOUT MCLKIN DGND Package: 28-lead TSSOP DD DVDD
030 Figure 1.
APPLICATIONS PLCs/DCS Multiplexing applications Process control Industrial instrumentation GENERAL DESCRIPTION
The AD7734 is a high precision, high throughput analog front 3-wire operation and is compatible with microcontrollers and end. True 16-bit p-p resolution is achievable with a total conversion digital signal processors. All interface inputs are Schmitt triggered. time of 500 μs (2 kHz channel switching), making it ideally suitable The device is specified for operation over the extended industrial for high resolution multiplexing applications. temperature range of –40°C to +105°C. The device can be configured via a simple digital interface, which Other devices in the AD7734 family are the AD7732 and the allows users to balance the noise performance against data AD7738. throughput up to 15.4 kHz. The AD7732 is similar to the AD7734, but its analog front end The analog front end features four single-ended input channels features two fully differential input channels. with unipolar or true bipolar input ranges to ±10 V while operating from a single +5 V analog supply. The device has an overrange The AD7738 analog front end is configurable for four fully and underrange detection capability and accepts an analog differential or eight single-ended input channels, features input overvoltage to ±16.5 V without degrading the 0.625 V to 2.5 V bipolar/unipolar input ranges, and accepts a performance of the adjacent channels. common-mode input voltage from 200 mV to AVDD – 300 mV. The AD7738 multiplexer output is pinned out externally, allowing The differential reference input features “No-Reference” detect the user to implement programmable gain or signal conditioning capability. The ADC also supports per channel system calibra- before being applied to the ADC. tion options. The digital serial interface can be configured for
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Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS TIMING SPECIFICATIONS Timing Diagrams ABSOLUTE MAXIMUM RATINGS ESD CAUTION TYPICAL PERFORMANCE CHARACTERISTICS OUTPUT NOISE AND RESOLUTION SPECIFICATION CHOPPING ENABLED CHOPPING DISABLED PIN CONFIGURATION AND FUNCTION DESCRIPTIONS REGISTER DESCRIPTION REGISTER ACCESS 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 AD7734 REGISTERS SINGLE CONVERSION AND READING DATA DUMP MODE CONTINUOUS CONVERSION MODE CONTINUOUS READ (CONTINUOUS CONVERSION) MODE CIRCUIT DESCRIPTION ANALOG FRONT END ANALOG INPUT’S EXTENDED VOLTAGE RANGE CHOPPING MULTIPLEXER, CONVERSION, AND DATA OUTPUT TIMING Σ-Δ ADC FREQUENCY RESPONSE VOLTAGE REFERENCE INPUTS REFERENCE DETECT I/O PORT CALIBRATION ADC ZERO-SCALE SELF-CALIBRATION PER CHANNEL SYSTEM CALIBRATION OUTLINE DIMENSIONS ORDERING GUIDE