Datasheet AD7656A (Analog Devices)

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250 kSPS, 6-Channel, Simultaneous Sampling, Bipolar 16-Bit ADC Data Sheet AD7656A FEATURES FUNCTIONAL BLOCK DIAGRAM 6 independent analog-to-digital converters (ADCs) VDD CONVST A CONVST B CONVST C AVCC DVCC True bipolar analog inputs Pin-/software-selectable ranges: ±10 V or ±5 V CS REF CLK CONTROL SER/PAR/SEL Fast throughput rate: 250 kSPS OSC LOGIC VDRIVE i CMOS® process technology STBY BUF Low power: 140 mW at 250 kSPS with 5 V supplies OUTPUT DB8/DOUT A 16-BIT SAR DRIVERS V1 T/H Wide input bandwidth 86.5 dB SNR at 50 kHz input frequency SCLK V2 T/H 16-BIT SAR On-chip reference and reference buffers OUTPUT DB9/DOUT B Parallel, serial, and daisy-chain interface modes BUF DRIVERS High speed serial interface V3 T/H 16-BIT SAR OUTPUT DRIVERS DB10/DOUT C Serial peripheral interface (SPI)/QSPI™/MICROWIRE®/DSP compatible V4 T/H 16-BIT SAR DATA/ OUTPUT CONTROL Power-down mode: 100 mW maximum DRIVERS BUF LINES 64-lead LQFP V5 T/H 16-BIT SAR RD Improved power supply sequencing (PSS) robustness WR/REFEN/DIS V6 T/H 16-BIT SAR AD7656A APPLICATIONS
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VSS AGND DGND
11127-
Power line monitoring systems
Figure 1.
Instrumentation and control systems Multi-axis positioning systems GENERAL DESCRIPTION
The AD7656A1 contains six 16-bit, fast, low power, successive The conversion process and data acquisition are controlled approximation analog-to-digital converters (ADCs) al in the using CONVST x signals and an internal oscillator. Three one package that is designed on the iCMOS® process (industrial CONVST x pins (CONVST A, CONVST B, and CONVST C) CMOS). iCMOS is a process combining high voltage silicon allow independent, simultaneous sampling of the three ADC with submicron CMOS and complementary bipolar technologies. pairs. The AD7656A has a high speed parallel and serial interface, It enables the development of a wide range of high performance al owing the device to interface with microprocessors or digital analog ICs, capable of 33 V operation in a footprint that no signal processors (DSPs). In serial interface mode, the AD7656A previous generation of high voltage devices could achieve. Unlike has a daisy-chain feature that al ows multiple ADCs to connect analog ICs using conventional CMOS processes, iCMOS to a single serial interface. The AD7656A can accommodate components can accept bipolar input signals while providing true bipolar input signals in the ±4 × VREF range and ±2 × VREF increased performance, which dramatically reduces power range. The AD7656A also contains an on-chip 2.5 V reference. consumption and package size. Multifunction pin names may be referenced by their relevant The AD7656A features throughput rates of up to 250 kSPS. It function only. contains wide bandwidth (12 MHz), track-and-hold amplifiers
PRODUCT HIGHLIGHTS
that can handle input frequencies up to 12 MHz. 1. Six 16-bit, 250 kSPS ADCs on board. 2. Six true bipolar, high impedance analog inputs. 3. Parallel and high speed serial interfaces. 1 Protected by U.S. Patent No. 6,731,232.
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Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION PRODUCT HIGHLIGHTS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS TIMING SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS POWER SUPPLY SEQUENCING THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TERMINOLOGY THEORY OF OPERATION CONVERTER DETAILS Track-and-Hold Amplifiers Analog Input ADC TRANSFER FUNCTION REFERENCE SECTION TYPICAL CONNECTION DIAGRAM DRIVING THE ANALOG INPUTS INTERFACE SECTION Parallel Interface (SER/PAR/SEL = 0) SOFTWARE SELECTION OF ADCS Changing the Analog Input Range (H/S SEL = 0) Changing the Analog Input Range (H/S SEL = 1) Serial Interface (SER/PAR/SEL = 1) SERIAL READ OPERATION DAISY-CHAIN MODE (DCEN = 1, SER//SEL = 1) Standby/Partial Power-Down Modes of Operation (SER/PAR/SEL = 0 or SER/PAR/SEL = 1) APPLICATION HINTS LAYOUT OUTLINE DIMENSIONS ORDERING GUIDE