Download AN990 Analog Sensor Conditioning Circuits an overview.pdf PDF

TitleAN990 Analog Sensor Conditioning Circuits an overview.pdf
TagsTypes Articles & News Stories
File Size262.9 KB
Total Pages16
Document Text Contents
Page 1

AN990
Analog Sensor Conditioning Circuits – An Overview
INTRODUCTION

Target Audience

This application note is intended for hardware design
engineers that need to condition the output of common
analog sensors.

Goals

• Review sensor applications (e.g., temperature)
• Review sensor types (e.g., voltage output)

• Show various conditioning circuits
• Give technical references

Description

Analog sensors produce a change in an electrical
property to indicate a change in its environment. This
change in electrical property needs to be conditioned
by an analog circuit before conversion to digital.
Further processing occurs in the digital domain but is
not addressed in this application note.

The applications mentioned are:

• Electrical
• Magnetic

• Temperature
• Humidity
• Force, Weight, Torque and Pressure

• Motion and Vibration
• Flow
• Fluid Level and Volume

• Light and Infrared (IR)
• Chemistry

For each type of electrical property, commonly used
conditioning circuits are shown. Each circuit has an
accompanying list of advantages and disadvantages,
and a list of sensor types appropriate for that circuit.
The electrical properties covered are:

• Voltage
• Current
• Resistance

• Capacitance
• Charge

In addition, circuit and firmware concerns common to
many embedded designs are briefly mentioned:

• Input Protection
• Sensor Failure Detection
• Filtering

• Analog-to-Digital (A-to-D) Conversion
• Correction of Results

References to documents that treat these subjects in
more depth have been included in the “References”
section.

SENSOR APPLICATIONS

This section reviews a few analog sensor applications.
For each application, a list of common sensor types is
given for convenience. A good resource for many of
these applications is OMEGA® Engineering’s
handbooks [1, 2].

There are many more analog sensors than the ones
discussed in this application note. For example:

• Time/frequency counters [14]
• Distance ranging sensor [25]
• Current sensing transformer [6]

Emphasis is placed on the electrical behavior of the
various sensors. It is necessary to know this
information when selecting an appropriate sensor
conditioning circuit.

Electrical

These applications measure the state at some point in
an electrical circuit. They include monitoring the
condition of a crucial electrical circuit or power source.

TABLE 1: ELECTRICAL APPLICATIONS

Author: Kumen Blake
Microchip Technology Inc.

Sensor Electrical Parameter

Voltage Voltage

Current Current

Charge Charge
© 2005 Microchip Technology Inc. DS00990A-page 1

Page 16

DS00990A-page 16 ! 2005 Microchip Technology Inc.

AMERICAS
Corporate Office
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7200
Fax: 480-792-7277
Technical Support:
http://support.microchip.com
Web Address:
www.microchip.com

Atlanta
Alpharetta, GA
Tel: 770-640-0034
Fax: 770-640-0307

Boston
Westborough, MA
Tel: 774-760-0087
Fax: 774-760-0088

Chicago
Itasca, IL
Tel: 630-285-0071
Fax: 630-285-0075

Dallas
Addison, TX
Tel: 972-818-7423
Fax: 972-818-2924

Detroit
Farmington Hills, MI
Tel: 248-538-2250
Fax: 248-538-2260

Kokomo
Kokomo, IN
Tel: 765-864-8360
Fax: 765-864-8387

Los Angeles
Mission Viejo, CA
Tel: 949-462-9523
Fax: 949-462-9608

San Jose
Mountain View, CA
Tel: 650-215-1444
Fax: 650-961-0286

Toronto
Mississauga, Ontario,
Canada
Tel: 905-673-0699
Fax: 905-673-6509

ASIA/PACIFIC
Australia - Sydney
Tel: 61-2-9868-6733
Fax: 61-2-9868-6755

China - Beijing
Tel: 86-10-8528-2100
Fax: 86-10-8528-2104

China - Chengdu
Tel: 86-28-8676-6200
Fax: 86-28-8676-6599

China - Fuzhou
Tel: 86-591-8750-3506
Fax: 86-591-8750-3521

China - Hong Kong SAR
Tel: 852-2401-1200
Fax: 852-2401-3431

China - Shanghai
Tel: 86-21-5407-5533
Fax: 86-21-5407-5066
China - Shenyang
Tel: 86-24-2334-2829
Fax: 86-24-2334-2393

China - Shenzhen
Tel: 86-755-8203-2660
Fax: 86-755-8203-1760

China - Shunde
Tel: 86-757-2839-5507
Fax: 86-757-2839-5571

China - Qingdao
Tel: 86-532-502-7355
Fax: 86-532-502-7205

ASIA/PACIFIC
India - Bangalore
Tel: 91-80-2229-0061
Fax: 91-80-2229-0062

India - New Delhi
Tel: 91-11-5160-8631
Fax: 91-11-5160-8632

Japan - Kanagawa
Tel: 81-45-471- 6166
Fax: 81-45-471-6122

Korea - Seoul
Tel: 82-2-554-7200
Fax: 82-2-558-5932 or
82-2-558-5934

Malaysia - Penang
Tel:011-604-646-8870
Fax:011-604-646-5086

Philippines - Manila
Tel: 011-632-634-9065
Fax: 011-632-634-9069

Singapore
Tel: 65-6334-8870
Fax: 65-6334-8850

Taiwan - Kaohsiung
Tel: 886-7-536-4818
Fax: 886-7-536-4803

Taiwan - Taipei
Tel: 886-2-2500-6610
Fax: 886-2-2508-0102

Taiwan - Hsinchu
Tel: 886-3-572-9526
Fax: 886-3-572-6459

EUROPE
Austria - Weis
Tel: 43-7242-2244-399
Fax: 43-7242-2244-393
Denmark - Ballerup
Tel: 45-4450-2828
Fax: 45-4485-2829

France - Massy
Tel: 33-1-69-53-63-20
Fax: 33-1-69-30-90-79

Germany - Ismaning
Tel: 49-89-627-144-0
Fax: 49-89-627-144-44

Italy - Milan
Tel: 39-0331-742611
Fax: 39-0331-466781

Netherlands - Drunen
Tel: 31-416-690399
Fax: 31-416-690340

England - Berkshire
Tel: 44-118-921-5869
Fax: 44-118-921-5820

WORLDWIDE SALES AND SERVICE

04/20/05

Similer Documents