ADC. AD7949 Datasheet

AD7949 Datasheet PDF


Part

AD7949

Description

250 kSPS PulSAR ADC

Manufacture

Analog Devices

Page 30 Pages
Datasheet
Download AD7949 Datasheet


AD7949 Datasheet
FEATURES
14-bit resolution with no missing codes
8-channel multiplexer with choice of inputs
Unipolar single-ended
Differential (GND sense)
Pseudobipolar
Throughput: 250 kSPS
INL/DNL: ±0.5/±0.25 LSB typical
SINAD: 85 dB @ 20 kHz
THD: −100 dB @ 20 kHz
Analog input range: 0 V to VREF with VREF up to VDD
Multiple reference types
Internal selectable 2.5 V or 4.096 V
External buffered (up to 4.096 V)
External (up to VDD)
Internal temperature sensor (TEMP)
Channel sequencer, selectable 1-pole filter, busy indicator
No pipeline delay, SAR architecture
Single-supply 2.3 V to 5.5 V operation with
1.8 V to 5.5 V logic interface
Serial interface compatible with SPI, MICROWIRE,
QSPI, and DSP
Power dissipation
2.9 mW @ 2.5 V/200 kSPS
10.8 mW @ 5 V/250 kSPS
Standby current: 50 nA
20-lead 4 mm × 4 mm LFCSP package
APPLICATIONS
www.DataSheet4U.com
Multichannel system monitoring
Battery-powered equipment
Medical instruments: ECG/EKG
Mobile communications: GPS
Power line monitoring
Data acquisition
Seismic data acquisition systems
Instrumentation
Process control
14-Bit, 8-Channel,
250 kSPS PulSAR ADC
AD7949
FUNCTIONAL BLOCK DIAGRAM
0.5V TO VDD – 0.5V 0.5V TO VDD
0.1µF
10µF
2.3V TO 5.5V
REFIN
REF
VDD
IN0
IN1
IN2
IN3
IN4
IN5
IN6
IN7
COM
BAND GAP
REF
TEMP
SENSOR
AD7949
MUX
14-BIT SAR SPI SERIAL
ADC
INTERFACE
ONE-POLE
LPF
SEQUENCER
GND
1.8V
VIO TO
VDD
CNV
SCK
SDO
DIN
Figure 1.
Table 1. Multichannel 14-/16-Bit PulSAR® ADCs
Type
Channels 250 kSPS 500 kSPS ADC Driver
14-Bit 8
AD7949
ADA4841-x
16-Bit 4
AD7682
ADA4841-x
16-Bit 8
AD7689 AD7699 ADA4841-x
GENERAL DESCRIPTION
The AD7949 is an 8-channel, 14-bit, charge redistribution
successive approximation register (SAR) analog-to-digital
converter (ADC) that operates from a single power supply, VDD.
The AD7949 contains all components for use in a multichannel,
low power data acquisition system, including a true 14-bit SAR
ADC with no missing codes; an 8-channel, low crosstalk
multiplexer that is useful for configuring the inputs as single-
ended (with or without ground sense), differential, or bipolar;
an internal low drift reference (selectable 2.5 V or 4.096 V) and
buffer; a temperature sensor; a selectable one-pole filter; and a
sequencer that is useful when channels are continuously
scanned in order.
The AD7949 uses a simple SPI interface for writing to the
configuration register and receiving conversion results. The SPI
interface uses a separate supply, VIO, which is set to the host
logic level. Power dissipation scales with throughput.
The AD7949 is housed in a tiny 20-lead LFCSP with operation
specified from −40°C to +85°C.
Rev. B
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
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.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2008–2009 Analog Devices, Inc. All rights reserved.

AD7949 Datasheet
AD7949
TABLE OF CONTENTS
Features .............................................................................................. 1 
Applications....................................................................................... 1 
Functional Block Diagram .............................................................. 1 
General Description ......................................................................... 1 
Revision History ............................................................................... 2 
Specifications..................................................................................... 3 
Timing Specifications .................................................................. 5 
Absolute Maximum Ratings............................................................ 7 
ESD Caution.................................................................................. 7 
Pin Configuration and Function Descriptions............................. 8 
Typical Performance Characteristics ............................................. 9 
Terminology .................................................................................... 12 
Theory of Operation ...................................................................... 13 
Overview...................................................................................... 13 
Converter Operation.................................................................. 13 
Transfer Functions...................................................................... 14 
Typical Connection Diagrams.................................................. 15 
Analog Inputs.............................................................................. 16 
Driver Amplifier Choice............................................................ 18 
REVISION HISTORY
5/09—Rev. A to Rev. B
Changes to Features Section, Applications Section, and
Figure 1 .............................................................................................. 1
wwCwh.aDnagtaesShtoeeStp4eUc.icfoicmations Section .................................................. 3
Changes to Timing Specifications Section.................................... 5
Changes to Table 5............................................................................ 7
Changes to Figure 4 and Table 6..................................................... 8
Changes to Figure 20...................................................................... 11
Changes to Converter Operation Section ................................... 13
Changes to Table 7.......................................................................... 14
Changes to Figure 25 and Figure 26............................................. 15
Changes to Bipolar Single Supply Section, Input Structure
Section, and Selectable Low-Pass Filter Section......................... 16
Changes to Input Configurations Section, Sequencer Section,
and Source Resistance Section...................................................... 17
Changes to Internal Reference/Temperature Sensor Section ... 18
Added Figure 30; Renumbered Sequentially .............................. 18
Changes to External Reference and Internal Buffer Section,
External Reference Section, and Reference Decoupling
Section.............................................................................................. 19
Added Figure 31 and Figure 32..................................................... 19
Changes to Power Supply Section ................................................ 20
Voltage Reference Output/Input .............................................. 18 
Power Supply............................................................................... 20 
Supplying the ADC from the Reference.................................. 20 
Digital Interface .............................................................................. 21 
Reading/Writing During Conversion, Fast Hosts.................. 21 
Reading/Writing After Conversion, Any Speed Hosts.......... 21 
Reading/Writing Spanning Conversion, Any Speed Host.... 21 
Configuration Register, CFG .................................................... 21 
General Timing Without a Busy Indicator ............................. 23 
General Timing with a Busy Indicator .................................... 24 
Channel Sequencer .................................................................... 25 
Read/Write Spanning Conversion Without a Busy Indicator
....................................................................................................... 26 
Read/Write Spanning Conversion with a Busy Indicator..... 27 
Application Hints ........................................................................... 28 
Layout .......................................................................................... 28 
Evaluating AD7949 Performance............................................. 28 
Outline Dimensions ....................................................................... 29 
Ordering Guide .......................................................................... 29 
Changed Reading/Writing During Conversion, Fast Hosts
Section to Reading/Writing After Conversion,
Any Speed Hosts............................................................................. 21
Changes to Configuration Register, CFG Section and
Table 9 .............................................................................................. 22
Added General Timing Without a Busy Indicator Section and
Figure 36 .......................................................................................... 23
Added General Timing with a Busy Indicator Section and
Figure 37 .......................................................................................... 24
Added Channel Sequencer Section, Examples Section, and
Figure 38 .......................................................................................... 25
Changes to Read/Write Spanning Conversion Without a Busy
Indicator Section and Figure 40 ................................................... 26
Changes to Read/Write Spanning Conversion with a Busy
Indicator Section and Figure 42 ................................................... 27
Changes to Evaluating AD7949 Performance Section .............. 28
Added Exposed Pad Notation to Outline Dimensions ............. 29
Changes to Ordering Guide .......................................................... 29
5/08—Rev. 0 to Rev. A
Changes to Ordering Guide .......................................................... 26
5/08—Revision 0: Initial Version
Rev. B | Page 2 of 32


Features Datasheet pdf 14-Bit, 8-Channel, 250 kSPS PulSAR ADC A D7949 FEATURES 14-bit resolution with n o missing codes 8-channel multiplexer w ith choice of inputs Unipolar single-en ded Differential (GND sense) Pseudobipo lar Throughput: 250 kSPS INL/DNL: ±0.5 /±0.25 LSB typical SINAD: 85 dB @ 20 k Hz THD: −100 dB @ 20 kHz Analog input range: 0 V to VREF with VREF up to VDD Multiple reference types Internal sele ctable 2.5 V or 4.096 V External buffer ed (up to 4.096 V) External (up to VDD) Internal temperature sensor (TEMP) Cha nnel sequencer, selectable 1-pole filte r, busy indicator No pipeline delay, SA R architecture Single-supply 2.3 V to 5 .5 V operation with 1.8 V to 5.5 V logi c interface Serial interface compatible with SPI, MICROWIRE, QSPI, and DSP Pow er dissipation 2.9 mW @ 2.5 V/200 kSPS 10.8 mW @ 5 V/250 kSPS Standby current: 50 nA 20-lead 4 mm × 4 mm LFCSP packa ge www.DataSheet4U.com FUNCTIONAL BLOC K DIAGRAM 0.5V TO VDD – 0.5V 0.1µF R EFIN 0.5V TO VDD 10µF REF 2.3V TO 5.5V VDD 1.8V VIO TO VDD BAND GAP R.
Keywords AD7949, datasheet, pdf, Analog Devices, 250, kSPS, PulSAR, ADC, D7949, 7949, 949, AD794, AD79, AD7, stock, pinout, distributor, price, schematic, inventory, databook, Electronic, Components, Parameters, parts, cross reference, chip, Semiconductor, circuit, Electric, manual, substitute, Equivalent




@ 2014 :: Datasheetspdf.com :: Semiconductors datasheet search & download site (Privacy Policy & Contact)