AD7709ARUZ Datasheet AD7709BRUZ, AD7709ARUZ-REEL7, AD7709BRUZ-REEL7 | P1-P3

AD7709

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REV. A

16-Bit - ADC with

Switchable Current Sources

FUNCTIONAL BLOCK DIAGRAM

IEXC1

IEXC2

IOUT1

IOUT2

IEXC3

OSCILLATOR

AND

PLL

XTAL2REFIN1(–) REFIN2(–)REFIN1(+) REFIN2(+) XTAL1

DOUT

RESET

RDY

SCLK

DIN

SERIAL

INTERFACE

AND

CONTROL

LOGIC

BUF

PGA

MUX

I/O PORT

16-BIT - ADC

AIN1

AIN2

AIN3/P3

AIN4/P4

AINCOM

AD7709

GND

PWRGND

P1/SW1 P2/SW2

I = 25A

FEATURES

16-Bit - ADC

Programmable Gain Front End

Simultaneous 50 Hz and 60 Hz Rejection at 20 Hz

Update Rate

VREF Select

™ Allows Absolute and Ratiometric

Measurement Capability

ISOURCE Select

™

16-Bit No Missing Codes

13-Bit p-p Resolution @ 20 Hz, 20 mV Range

16-Bit p-p Resolution @ 20 Hz, 2.56 V Range

INTERFACE

3-Wire Serial

SPI

QSPI™,

MICROWIRE™,

and DSP Compatible

Schmitt Trigger on SCLK

POWER

Specified for Single 3 V and 5 V Operation

Normal: 1.25 mA Typ @ 3 V

Power-Down: 7 A (32.768 kHz Crystal Running)

ON-CHIP FUNCTIONS

Rail-to-Rail Input Buffer and PGA

Selectable Reference Inputs

3 Switchable, Ratioed Current Sources for

Measurements

4-Bit Digital I/O Port

Low-Side Power Switches

APPLICATIONS

Sensor Measurement

Temperature Measurement

Pressure Measurements

Weigh Scales

Portable Instrumentation

4–20 mA Loops

GENERAL DESCRIPTION

The AD7709 is a complete analog front end for low frequency

measurement applications. It contains a 16-bit ⌺-⌬ ADC, selectable

reference inputs, three switchable matched excitation current

sources, low-side power switches, and a digital I/O port. The

16-bit channel with PGA accepts fully differential, unipolar,

and

bipolar input signal ranges from 1.024 ⫻ REFIN/128 to

1.024 ⫻ REFIN. It can be configured as two fully differential

input channels or four pseudo-differential input channels. Signals

can be converted directly from a transducer without the need for

signal conditioning.

The device operates from a 32.768 kHz crystal with an on-chip

PLL generating the required internal operating frequency. The

output data rate from the part is software programmable. The

p-p

resolution from the part varies with the programmed gain

and output data rate.

The part operates from a single 3 V or 5 V supply. When

operating from 3 V supplies, the power dissipation for the part

is 3.75 mW. The AD7709 is housed in a 24-lead TSSOP package.

AD7709* PRODUCT PAGE QUICK LINKS

Last Content Update: 02/23/2017

COMPARABLE PARTS

View a parametric search of comparable parts.

EVALUATION KITS

• AD7709 Evaluation Board

DOCUMENTATION

Application Notes

• AN-202: An IC Amplifier User’s Guide to Decoupling,

Grounding, and Making Things Go Right for a Change

• AN-283: Sigma-Delta ADCs and DACs

• AN-311: How to Reliably Protect CMOS Circuits Against

Power Supply Overvoltaging

• AN-388: Using Sigma-Delta Converters-Part 1

• AN-389: Using Sigma-Delta Converters-Part 2

• AN-397: Electrically Induced Damage to Standard Linear

Integrated Circuits:

• AN-607: Selecting a Low Bandwidth (<15 kSPS) Sigma-

Delta ADC

• AN-608: Input Buffers on Sigma-Delta ADCs

• AN-609: Chopping on Sigma-Delta ADCs

• AN-610: The PGA on Sigma-Delta ADCs

• AN-611: 50 Hz/60Hz Rejection on Sigma-Delta ADCs

• AN-615: Peak-to-Peak Resolution Versus Effective

Resolution

Data Sheet

• AD7709: 16-Bit Sigma Delta ADC with Switchable Current

Sources Data Sheet

TOOLS AND SIMULATIONS

• Sigma-Delta ADC Tutorial

REFERENCE MATERIALS

Technical Articles

• Delta-Sigma Rocks RF, As ADC Designers Jump On Jitter

• MS-2210: Designing Power Supplies for High Speed ADC

• Part 1: Circuit Suggestions Using Features and

Functionality of New Sigma-Delta ADCs

• Part 2: Circuit Suggestions Using Features and

Functionality of New Sigma-Delta ADCs

DESIGN RESOURCES

• AD7709 Material Declaration

• PCN-PDN Information

• Quality And Reliability

• Symbols and Footprints

DISCUSSIONS

View all AD7709 EngineerZone Discussions.

SAMPLE AND BUY

Visit the product page to see pricing options.

TECHNICAL SUPPORT

Submit a technical question or find your regional support

number.

DOCUMENT FEEDBACK

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REV. A

AD7709

–2–

TABLE OF CONTENTS

FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

GENERAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 1

FUNCTIONAL BLOCK DIAGRAM . . . . . . . . . . . . . . . . . 1

SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

TIMING CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . 6

ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . 8

ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

PIN CONFIGURATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

PIN FUNCTION DESCRIPTIONS . . . . . . . . . . . . . . . . . . 9

TYPICAL PERFORMANCE CHARACTERISTICS . . . . 10

ADC CIRCUIT INFORMATION . . . . . . . . . . . . . . . . . . . 11

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

S-D ADC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

NOISE PERFORMANCE . . . . . . . . . . . . . . . . . . . . . . . . . 13

ON-CHIP REGISTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Communications Register . . . . . . . . . . . . . . . . . . . . . . . . 14

Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Filter Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

ADC Data Result Register . . . . . . . . . . . . . . . . . . . . . . . . 18

CONFIGURING THE AD7709 . . . . . . . . . . . . . . . . . . . . . 19

DIGITAL INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

MICROCOMPUTER/MICROPROCESSOR

INTERFACING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

AD7709-to-68HC11 Interface . . . . . . . . . . . . . . . . . . . . . 21

AD7709-to-8051 Interface . . . . . . . . . . . . . . . . . . . . . . . . 21

AD7709-to-ADSP-2103/ADSP-2105 Interface . . . . . . . . 21

CIRCUIT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . 22

Analog Input Channels . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Programmable Gain Amplifier . . . . . . . . . . . . . . . . . . . . . 23

Bipolar/Unipolar Configuration . . . . . . . . . . . . . . . . . . . . 23

Data Output Coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Excitation Currents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Crystal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Reference Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Reset Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Power-Down Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Grounding and Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Pressure Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Temperature Measurement . . . . . . . . . . . . . . . . . . . . . . . 26

3-Wire RTD Configurations . . . . . . . . . . . . . . . . . . . . . . 27

Smart Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . 29

Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P24 P25-P27 P28-P30 P31-P33

AD7709ARUZ

Mfr. #:

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Manufacturer:

Analog Devices Inc.

Description:

Analog to Digital Converters - ADC 16-Bit w/ Current Sources

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AD7709ARUZ

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