AD7731BR Analog Devices Inc, AD7731BR Datasheet - Page 43

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AD7731BR

Manufacturer Part Number
AD7731BR
Description
A/D Converter (A-D) IC
Manufacturer
Analog Devices Inc
Datasheet

Specifications of AD7731BR

Peak Reflow Compatible (260 C)
No
No. Of Bits
24 Bit
Leaded Process Compatible
No
Mounting Type
Surface Mount
Features
Low-Noise, High-Throughput
No. Of Channels
6
Interface Type
Serial
Rohs Status
RoHS non-compliant
Number Of Bits
24
Sampling Rate (per Second)
6.4k
Data Interface
DSP, Serial, SPI™
Number Of Converters
1
Power Dissipation (max)
125mW
Voltage Supply Source
Analog and Digital
Operating Temperature
-40°C ~ 85°C
Package / Case
24-SOIC (0.300", 7.50mm Width)
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
For Use With
EVAL-AD7731EBZ - BOARD EVALUATION FOR AD7731
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant

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REV. A
PAGE INDEX
Topic
FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
GENERAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 1
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
TIMING CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . 4
ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . 5
ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
DETAILED FUNCTIONAL BLOCK DIAGRAM . . . . . . . 6
SIGNAL PROCESSING CHAIN . . . . . . . . . . . . . . . . . . . . . 7
PIN CONFIGURATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
PIN FUNCTION DESCRIPTIONS . . . . . . . . . . . . . . . . . . 7
TERMINOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
OUTPUT NOISE AND RESOLUTION
ON-CHIP REGISTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
READING FROM AND WRITING TO THE
CALIBRATION OPERATION SUMMARY . . . . . . . . . . . 21
CIRCUIT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 22
ANALOG INPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
REFERENCE INPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
SIGMA-DELTA MODULATOR . . . . . . . . . . . . . . . . . . . . 24
DIGITAL FILTERING . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
CALIBRATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
USING THE AD7731 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
POWER SUPPLIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
REV. 0
SPECIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Summary Of On-Chip Registers . . . . . . . . . . . . . . . . . . . 12
Communications Register . . . . . . . . . . . . . . . . . . . . . . . . 13
Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Mode Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Filter Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Offset Calibration Register . . . . . . . . . . . . . . . . . . . . . . . 19
Gain Calibration Register . . . . . . . . . . . . . . . . . . . . . . . . 19
Test Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
ON-CHIP REGISTERS . . . . . . . . . . . . . . . . . . . . . . . . . 20
Analog Input Channels . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Analog Input Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Bipolar/Unipolar Inputs . . . . . . . . . . . . . . . . . . . . . . . . . 23
Burnout Currents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Reference Detect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Filter Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
First Stage Filter/SKIP Mode Enabled . . . . . . . . . . . . . . 25
Second Stage Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Normal FIR Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 25
FASTStep™ Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Internal Zero-Scale Calibration . . . . . . . . . . . . . . . . . . . . 29
Internal Full-Scale Calibration . . . . . . . . . . . . . . . . . . . . 30
System Zero-Scale Calibration . . . . . . . . . . . . . . . . . . . . 30
System Full-Scale Calibration . . . . . . . . . . . . . . . . . . . . . 30
Span and Offset Limits . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Power-Up and Calibration . . . . . . . . . . . . . . . . . . . . . . . 31
Drift Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Clocking and Oscillator Circuit . . . . . . . . . . . . . . . . . . . . 32
System Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . 32
Single-Shot Conversions . . . . . . . . . . . . . . . . . . . . . . . . . 32
Reset Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Standby Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Digital Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Grounding and Layout . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Evaluating the AD7731 Performance . . . . . . . . . . . . . . . 33
Page
–43–
Topic
SERIAL INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
CONFIGURING THE AD7731 . . . . . . . . . . . . . . . . . . . . . 36
MICROCOMPUTER/MICROPROCESSOR
APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . 44
TABLE INDEX
Table
Table I.
Table II.
Table III.
Table IV.
Table V.
Table VI.
Table VII.
Table VIII.
Table IX.
Table X.
Table XI.
Table XII.
Table XIII.
Table XIV.
Table XV.
Table XVI.
Table XVII.
Table XVIII. Time to First and Subsequent Outputs
Table XIX.
Table XX.
Write Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Read Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
INTERFACING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
AD7731 to 68HC11 Interface . . . . . . . . . . . . . . . . . . . . . 37
AD7731 to 8051 Interface . . . . . . . . . . . . . . . . . . . . . . . 37
AD7731 to ADSP-2103/ADSP-2105 Interface . . . . . . . . 38
Data Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Programmable Logic Controllers . . . . . . . . . . . . . . . . . . 39
Pressure Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Temperature Measurement . . . . . . . . . . . . . . . . . . . . . . . 40
Bipolar Input Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Title
Output Noise vs. Input Range and
Update Rate (CHP = 0, SKIP = 1) . . . . . . . 10
Peak-to-Peak Resolution vs. Input Range
and Update Rate (CHP = 0, SKIP = 1) . . . . 10
Output Noise vs. Input Range and
Update Rate (CHP = 1, SKIP = 0) . . . . . . . 11
Peak-to-Peak Resolution vs. Input Range
and Update Rate (CHP = 1, SKIP = 0) . . . . 11
Summary of On-Chip Registers . . . . . . . . . . 12
Communications Register . . . . . . . . . . . . . . 13
Read/Write Mode . . . . . . . . . . . . . . . . . . . . 13
Register Selection . . . . . . . . . . . . . . . . . . . . 14
Status Register . . . . . . . . . . . . . . . . . . . . . . . 14
Mode Register . . . . . . . . . . . . . . . . . . . . . . . 15
Operating Modes . . . . . . . . . . . . . . . . . . . . . 15
Input Range Selection . . . . . . . . . . . . . . . . . 17
Channel Selection . . . . . . . . . . . . . . . . . . . . 18
Filter Register . . . . . . . . . . . . . . . . . . . . . . . 18
SF Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Calibration Operations . . . . . . . . . . . . . . . . 21
Reset Events . . . . . . . . . . . . . . . . . . . . . . . . 22
Following Channel Change . . . . . . . . . . . . . 28
Pseudo-Code for Initiating a
Self-Calibration After Power-On/Reset . . . . 36
Pseudo-Code for Looping Through Three
Fully-Differential Channels . . . . . . . . . . . . . 36
AD7731
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