250 kSPS, 6-Channel, Simultaneous Sampling, Bipolar 16-/14-/12-Bit ADC Data Sheet AD7656/AD7657/AD7658 FEATURES FUNCTIONAL BLOCK DIAGRAM V CONVST A CONVST B CONVST C AV DV DD CC CC 6 independent ADCs True bipolar analog inputs CS Pin-/software-selectable ranges: 10 V, 5 V CLK REF SER/PAR CONTROL OSC Fast throughput rate: 250 kSPS LOGIC V DRIVE STBY iCMOS process technology BUF OUTPUT Low power DOUT A 16-/14-/12-BIT SAR DRIVERS V1 T/H 140 mW at 250 kSPS with 5 V supplies SCLK Wide input bandwidth V2 T/H 16-/14-/12-BIT SAR 86.5 dB SNR at 50 kHz input frequency OUTPUT DOUT B BUF DRIVERS On-chip reference and reference buffers V3 T/H 16-/14-/12-BIT SAR OUTPUT Parallel, serial, and daisy-chain interface modes DRIVERS DOUT C High speed serial interface V4 T/H 16-/14-/12-BIT SAR DATA/ SPI-/QSPI-/MICROWIRE-/DSP-compatible OUTPUT CONTROL DRIVERS BUF LINES Standby mode: 100 W maximum V5 T/H 16-/14-/12-BIT SAR RD 64-lead LQFP WR T/H V6 16-/14-/12-BIT SAR APPLICATIONS AD7656/AD7657/AD7658 V AGND DGND Power line monitoring systems SS Instrumentation and control systems Figure 1. Multi-axis positioning systems GENERAL DESCRIPTION 1 The AD7656/AD7657/AD7658 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 a high speed parallel and serial interface, allowing the devices with submicron CMOS and complementary bipolar technol- to interface with microprocessors or DSPs. In serial interface ogies. It enables the development of a wide range of high 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 V range and 2 V range. The AD7656/ REF REF while providing increased performance, which dramatically 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. Rev. D Information furnished by Analog Devices is believed to be accurate and reliable. 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All rights reserved. 05020-001AD7656/AD7657/AD7658 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Typical Performance Characteristics ........................................... 14 Applications ....................................................................................... 1 Terminology .................................................................................... 18 Functional Block Diagram .............................................................. 1 Theory of Operation ...................................................................... 20 General Description ......................................................................... 1 Converter Details ....................................................................... 20 Product Highlights ........................................................................... 1 ADC Transfer Function ............................................................. 21 Revision History ............................................................................... 2 Reference Section ....................................................................... 21 Specifications ..................................................................................... 3 Typical Connection Diagram ................................................... 21 AD7656 .......................................................................................... 3 Driving the Analog Inputs ........................................................ 22 AD7657 .......................................................................................... 5 Interface Section ......................................................................... 22 AD7658 .......................................................................................... 7 Application Hints ........................................................................... 29 Timing Specifications .................................................................. 9 Layout .......................................................................................... 29 Absolute Maximum Ratings .......................................................... 10 Power Supply Configuration..................................................... 29 Thermal Resistance .................................................................... 10 Outline Dimensions ....................................................................... 30 ESD Caution ................................................................................ 10 Ordering Guide .......................................................................... 30 Pin Configuration and Function Descriptions ........................... 11 REVISION HISTORY 3/12Rev. C to Rev D 4/06Rev. 0 to Rev. A Changes to Figure 26 ...................................................................... 22 Added AD7657/AD7658 parts ......................................... Universal 8/10Rev. B to Rev. C Changes to Table 1 ............................................................................. 3 Changes to t1 Unit in Table 4 ........................................................... 9 Changes to Table 5 .......................................................................... 10 Changes to VDD to AVCC Rating in Table 5 .................................. 10 3/06Revision 0: Initial Version Added Power Supply Configuration Section .............................. 29 Added Figure 36 .............................................................................. 29 V to AV DD CC 1/10Rev. A to Rev. B Changes to Unit of DC Accuracy Parameter, Table 1 .................. 3 Changes to DC Accuracy Parameter, Table 2 ............................... 5 Changes to DC Accuracy Parameter, Table 3 ............................... 7 Changes to Terminology Section.................................................. 18 Updated Outline Dimensions ....................................................... 30 Changes to Ordering Guide .......................................................... 30 Rev. D Page 2 of 32