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a

AD22151

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700

World Wide Web Site: http://www.analog.com

Fax: 781/326-8703

© Analog Devices, Inc., 1997

Linear Output

Magnetic Field Sensor

FUNCTIONAL BLOCK DIAGRAM

TEMP REF

DEMOD

SWITCHES

OUT AMP

REF

AD22151

FEATURES

Adjustable Offset to Unipolar or Bipolar Operation

Low Offset Drift Over Temperature Range

Gain Adjustable Over Wide Range

Low Gain Drift Over Temperature Range

Adjustable First Order Temperature Compensation

APPLICATIONS

Automotive

Throttle Position Sensing

Pedal Position Sensing

Suspension Position Sensing

Valve Position Sensing

Industrial

Absolute Position Sensing

Proximity Sensing

GENERAL DESCRIPTION

The AD22151 is a linear magnetic field transducer. The sensor

output is a voltage proportional to a magnetic field applied

perpendicularly to the package top surface.

The sensor combines integrated bulk Hall cell technology and

instrumentation circuitry to minimize temperature related drifts

associated with silicon Hall cell characteristics. The architecture

maximizes the advantages of a monolithic implementation while

allowing sufficient versatility to meet varied application require-

ments with a minimum number of components.

Principle features include dynamic offset drift cancellation and a

built-in temperature sensor. Designed for single +5 volt supply

operation, the AD22151 achieves low drift offset and gain op-

eration over –40

°C to +150°C. Temperature compensation can

accommodate a number of magnetic materials commonly uti-

lized in economic position sensor assemblies.

The transducer may be configured for specific signal gains de-

pendent upon application requirements. Output voltage can be

adjusted from fully bipolar (reversible) field operation to fully

unipolar field sensing.

The voltage output achieves near rail-to-rail dynamic range,

capable of supplying 1 mA into large capacitive loads. The sig-

nal is ratiometric to the positive supply rail in all configurations.

NC

R1

GND

R3

R2

AD22151

NC = NO CONNECT

OUTPUT

0.1 F

Figure 1. Typical Bipolar Configuration with Low

(< –500 ppm) Compensation

NC

R1

GND

R3

R2

AD22151

NC = NO CONNECT

OUTPUT

0.1 F

R4

Figure 2. Typical Unipolar Configuration with High

(≈ –2000 ppm) Compensation