Datasheet AD7864 (Analog Devices)

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4-Channel, Simultaneous Sampling, High Speed, 12-Bit ADC AD7864 FEATURES FUNCTIONAL BLOCK DIAGRAM AVDD V V DV V High speed (1.65 μs) 12-bit ADC REF REFGND DD DRIVE 4 simultaneously sampled inputs TRACK-AND-HOLD STBY 6kΩ 2.5V 4 track-and-hold amplifiers ×4 DGND REFERENCE VIN1A SIGNAL 0.35 μs track-and-hold acquisition time V SCALING IN1B AGND AD7864 1.65 μs conversion time per channel VIN2A SIGNAL V RD IN2B SCALING HW/SW select of channel sequence for conversion MUX VIN3A SIGNAL DB11 Single-supply operation OUTPUT VIN3B SCALING 12-BIT DATA ADC Selection of input ranges REGISTERS VIN4A SIGNAL DB0 ±10 V, ±5 V for AD7864-1 VIN4B SCALING SOFTWARE DB0 TO DB3 CS ±2.5 V for AD7864-3 0 V to 2.5 V, 0 V to 5 V for AD7864-2 LATCH FRSTDATA High speed parallel interface that allows BUSY WR CONVERSION CONTROL LOGIC INT/EXT CLOCK Interfacing to 3 V processors EOC INT SELECT CLOCK Low power, 90 mW typical
1
Power saving mode, 20 μW typical
00
CONVST SL1 SL2 SL3 SL4 H/S CLKIN INT/EXT AGND AGND
1-
SEL CLK
34
Overvoltage protection on analog inputs
01 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
GENERAL DESCRIPTION
operation depends on the read cycle time of the processor. See The AD7864 is a high speed, low power, 4-channel, simulta- the Timing and Contro lsection. The AD7864 is available in a neous sampling 12-bit analog-to-digital converter (ADC) that small (0.3 square inch area) 44-lead MQFP. operates from a single 5 V supply. The part contains a 1.65 μs
PRODUCT HIGHLIGHTS
successive approximation ADC, four track-and-hold amplifiers, 1. Four track-and-hold amplifiers and a fast (1.65 μs) 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 A single conversion start signal (CONVST) simultaneously places signal processing input range of ±2.5 V; the AD7864-2 can all the track-and-holds into hold and initiates a conversion se- be used in unipolar, 0 V to 2.5 V and 0 V to 5 V, quence for the selected channels. The EOC signal indicates the end applications. 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 license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Tel: 781.329.4700 www.analog.com Trademarks and registered trademarks are the property of their respective owners. Fax: 781.461.3113 ©1998–2009 Analog Devices, Inc. All rights reserved.
Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM PRODUCT HIGHLIGHTS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS TIMING CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TERMINOLOGY THEORY OF OPERATION CONVERTER DETAILS Track-and-Hold Amplifiers Reference CIRCUIT DESCRIPTION ANALOG INPUT AD7864-1 AD7864-2 AD7864-3 SELECTING A CONVERSION SEQUENCE TIMING AND CONTROL Reading Between Each Conversion in the Conversion Sequence Reading After the Conversion Sequence USING AN EXTERNAL CLOCK STANDBY MODE OPERATION ACCESSING THE OUTPUT DATA REGISTERS OFFSET AND FULL-SCALE ADJUSTMENT POSITIVE FULL-SCALE ADJUST NEGATIVE FULL-SCALE ADJUST DYNAMIC SPECIFICATIONS SIGNAL-TO-NOISE RATIO (SNR) EFFECTIVE NUMBER OF BITS INTERMODULATION DISTORTION AC LINEARITY PLOTS MEASURING APERTURE JITTER MICROPROCESSOR INTERFACING AD7864 TO ADSP-2100/ADSP-2101/ADSP-2102 INTERFACE AD7864 TO TMS320C5x INTERFACE AD7864 TO MC68HC000 INTERFACE VECTOR MOTOR CONTROL MULTIPLE AD7864S IN A SYSTEM OUTLINE DIMENSIONS ORDERING GUIDE