4-Channel, Simultaneous Sampling, High Speed, 12-Bit ADC AD7864 FEATURES FUNCTIONAL BLOCK DIAGRAM AV DV V V V GND DD REF REF DD DRIVE High speed (1.65 s) 12-bit ADC 4 simultaneously sampled inputs TRACK-AND-HOLD 6k 2.5V STBY DGND 4 REFERENCE 4 track-and-hold amplifiers V IN1A SIGNAL V SCALING IN1B AGND 0.35 s track-and-hold acquisition time AD7864 V IN2A SIGNAL 1.65 s conversion time per channel RD V SCALING IN2B HW/SW select of channel sequence for conversion MUX V IN3A SIGNAL DB11 OUTPUT Single-supply operation V 12-BIT SCALING IN3B DATA ADC REGISTERS Selection of input ranges DB0 V IN4A SIGNAL V SCALING IN4B 10 V, 5 V for AD7864-1 SOFTWARE CS DB0 TO DB3 LATCH 2.5 V for AD7864-3 0 V to 2.5 V, 0 V to 5 V for AD7864-2 FRSTDATA WR High speed parallel interface that allows BUSY CONVERSION INT/EXT CLOCK INT CONTROL LOGIC EOC Interfacing to 3 V processors SELECT CLOCK Low power, 90 mW typical SL1 SL2 SL3 SL4 CLKIN AGND AGND Power saving mode, 20 W typical CONVST H/S INT/EXT SEL CLK Overvoltage protection on analog inputs Figure 1. APPLICATIONS Data is read from the part by a 12-bit parallel data bus using the AC motor control standard CS and RD signals. Maximum throughput for a single Uninterrupted power supplies channel is 500 kSPS. For all four channels, the maximum throughput Data acquisition systems is 130 kSPS for the read-during-conversion sequence operation. Communications The throughput rate for the read-after-conversion sequence operation depends on the read cycle time of the processor. See GENERAL DESCRIPTION the Timing and Control section. The AD7864 is available in a The AD7864 is a high speed, low power, 4-channel, simulta- small (0.3 square inch area) 44-lead MQFP. neous sampling 12-bit analog-to-digital converter (ADC) that operates from a single 5 V supply. The part contains a 1.65 s PRODUCT HIGHLIGHTS successive approximation ADC, four track-and-hold amplifiers, 1. Four track-and-hold amplifiers and a fast (1.65 s) ADC for a 2.5 V reference, an on-chip clock oscillator, signal conditioning simultaneous sampling and conversion of any subset of the circuitry, and a high speed parallel interface. The input signals four channels. on four channels sample simultaneously preserving the relative 2. A single 5 V supply consuming only 90 mW typical, makes phase information of the signals on the four analog inputs. The it ideal for low power and portable applications. See the part accepts analog input ranges of 10 V, 5 V (AD7864-1), 0 V Standby Mode Operation section. to +2.5 V, 0 V to +5 V (AD7864-2), and 2.5 V (AD7864-3). 3. High speed parallel interface for easy connection to micro- Any subset of the four channels can be converted to maximize processors, microcontrollers, and digital signal processors. the throughput rate on the selected sequence. Select the channels to 4. Available in three versions with different analog input convert via hardware (channel select input pins) or software (pro- ranges. The AD7864-1 offers the standard industrial input gramming the channel select register). ranges of 10 V and 5 V the AD7864-3 offers the common signal processing input range of 2.5 V the AD7864-2 can CONVST A single conversion start signal ( ) simultaneously places be used in unipolar, 0 V to 2.5 V and 0 V to 5 V, all the track-and-holds into hold and initiates a conversion se- applications. quence for the selected channels. The EOC signal indicates the end 5. Features very tight aperture delay matching between the of each individual conversion in the selected conversion sequence. four input sample-and-hold amplifiers. The BUSY signal indicates the end of the conversion sequence. Rev. D 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Fax: 781.461.3113 19982009 Analog Devices, Inc. All rights reserved. 01341-001AD7864 TABLE OF CONTENTS Features .............................................................................................. 1 Standby Mode Operation .......................................................... 18 Applications ....................................................................................... 1 Accessing the Output Data Registers ....................................... 18 General Description ......................................................................... 1 Offset and Full-Scale Adjustment ................................................ 20 Functional Block Diagram .............................................................. 1 Positive Full-Scale Adjust .......................................................... 20 Product Highlights ........................................................................... 1 Negative Full-Scale Adjust ......................................................... 20 Revision History ............................................................................... 2 Dynamic Specifications ................................................................. 21 Specif ications ..................................................................................... 3 Signal-to-Noise Ratio (SNR)..................................................... 21 Timing Characteristics ................................................................ 5 Effective Number of Bits ........................................................... 21 Absolute Maximum Ratings ............................................................ 6 Intermodulation Distortion ...................................................... 21 ESD Caution .................................................................................. 6 AC Linearity Plots ...................................................................... 22 Pin Configuration and Function Descriptions ............................. 7 Measuring Aperture Jitter .......................................................... 22 Terminology ...................................................................................... 9 Microprocessor Interfacing ........................................................... 24 Theory of Operation ...................................................................... 11 AD7864 to ADSP-2100/ADSP-2101/ADSP-2102 Interface . 24 Converter Details ........................................................................ 11 AD7864 to TMS320C5x Interface ............................................ 24 Circuit Description ......................................................................... 13 AD7864 to MC68HC000 Interface .......................................... 24 Analog Input ............................................................................... 13 Vector Motor Control ................................................................ 25 Selecting a Conversion Sequence ................................................. 15 Multiple AD7864s in A System ................................................. 26 Timing and Control ................................................................... 15 Outline Dimensions ....................................................................... 27 Using an External Clock ............................................................ 17 Ordering Guide .......................................................................... 27 REVISION HISTORY 2/09Rev. C to Rev. D 3/04Rev. A to Rev. B. Change to t2 Parameter, Table 2 ...................................................... 5 Changes to Specifications and to Footnote 4 ................................. 2 Changes to Timing Characteristics Footnote 1 ............................. 4 2/09Rev. B to Rev. C Addition to Absolute Maximum Ratings ....................................... 5 Updated Format .................................................................. Universal Changes to Ordering Guide ............................................................. 5 Changes to t5 Timing Parameter, Table 2....................................... 5 Changes to Figure 7 ......................................................................... 11 Changes to Figure 15 ...................................................................... 20 Changes to Figure 11 ...................................................................... 13 Changes to AD7864 to MC68HC000 Interface Section ............ 24 Updated Outline Dimensions ....................................................... 19 Changes to Figure 25 ...................................................................... 24 Added Revision History ................................................................ 20 Updated Outline Dimensions ....................................................... 29 Updated Publication Code ............................................................ 20 Changes to Ordering Guide .......................................................... 29 Rev. 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