Datasheet AD7656, AD7657, AD7658 (Analog Devices)

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250 kSPS, 6-Channel, Simultaneous Sampling, Bipolar 16-/14-/12-Bit ADC Data Sheet AD7656/ AD7657/ AD7658 FEATURES FUNCTIONAL BLOCK DIAGRAM 6 independent ADCs VDD CONVST A CONVST B CONVST C AVCC DVCC True bipolar analog inputs Pin-/software-selectable ranges: ±10 V, ±5 V CS REF CLK Fast throughput rate: 250 kSPS CONTROL OSC SER/PAR LOGIC VDRIVE i CMOS process technology STBY BUF Low power OUTPUT DOUT A 16-/14-/12-BIT SAR DRIVERS V1 T/H 140 mW at 250 kSPS with 5 V supplies Wide input bandwidth SCLK 86.5 dB SNR at 50 kHz input frequency V2 T/H 16-/14-/12-BIT SAR OUTPUT DOUT B On-chip reference and reference buffers BUF DRIVERS Parallel, serial, and daisy-chain interface modes V3 T/H 16-/14-/12-BIT SAR OUTPUT DRIVERS DOUT C High speed serial interface SPI-/QSPI™-/MICROWIRE™-/DSP-compatible V4 T/H 16-/14-/12-BIT SAR DATA/ OUTPUT CONTROL Standby mode: 100 µW maximum DRIVERS BUF LINES 64-lead LQFP V5 T/H 16-/14-/12-BIT SAR RD WR V6 T/H APPLICATIONS 16-/14-/12-BIT SAR AD7656/AD7657/AD7658
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Power line monitoring systems VSS AGND DGND
05020-
Instrumentation and control systems
Figure 1.
Multi-axis positioning systems GENERAL DESCRIPTION
The AD7656/AD7657/AD76581 contain six 16-/14-/12-bit, The conversion process and data acquisition are controlled fast, low power, successive approximation ADCs all in the one using CONVST signals and an internal oscillator. Three package that is designed on the iCMOS™ process (industrial CONVST pins allow independent, simultaneous sampling of CMOS). iCMOS is a process combining high voltage silicon the three ADC pairs. The AD7656/AD7657/AD7658 all have with submicron CMOS and complementary bipolar technol- a high speed parallel and serial interface, allowing the devices ogies. It enables the development of a wide range of high to interface with microprocessors or DSPs. In serial interface performance analog ICs, capable of 33 V operation in a mode, the parts have a daisy-chain feature that allows multiple footprint that no previous generation of high voltage parts ADCs to connect to a single serial interface. The AD7656/ could achieve. Unlike analog ICs using conventional CMOS AD7657/AD7658 can accommodate true bipolar input signals processes, iCMOS components can accept bipolar input signals in the ±4 × VREF range and ±2 × VREF range. The AD7656/ while providing increased performance, which dramatical y AD7657/AD7658 also contain an on-chip 2.5 V reference. reduces power consumption and package size.
PRODUCT HIGHLIGHTS
The AD7656/AD7657/AD7658 feature throughput rates up 1. Six 16-/14-/12-bit, 250 kSPS ADCs on board. to 250 kSPS. The parts contain low noise, wide bandwidth, 2. Six true bipolar, high impedance analog inputs. track-and-hold amplifiers that can handle input frequencies 3. Parallel and high speed serial interfaces. up to 12 MHz. 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 AD7656 AD7657 AD7658 Timing Specifications Absolute Maximum Ratings Thermal Resistance ESD Caution Pin Configuration and Function Descriptions Typical Performance Characteristics Terminology Theory of Operation Converter Details Track-and-Hold Section Analog Input Section ADC Transfer Function Reference Section Typical Connection Diagram Driving the Analog Inputs Interface Section Parallel Interface (SER/ = 0) Software Selection of ADCs Changing the Analog Input Range (/S SEL = 0) Changing the Analog Input Range (/S SEL = 1) Serial Interface (SER/ = 1) Serial Read Operation Daisy-Chain Mode (DCEN = 1, SER/ = 1) Standby/Partial Power-Down Modes of Operation Application Hints Layout Power Supply Configuration Outline Dimensions Ordering Guide