Analog Devices AD22151 a Datasheet
Linear Output
NC
R1
GND
R3
R2
V
CC
AD22151
NC = NO CONNECT
OUTPUT
0.1F
NC
R1
GND
R3
R2
V
CC
AD22151
NC = NO CONNECT
OUTPUT
0.1F
R4
Magnetic Field Sensor
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
Ratiometric to V
CC
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 requirements with a minimum number of components.
Principal features include dynamic offset drift cancellation
and a built-in temperature sensor. Designed for single 5 V
supply operation, the AD22151 achieves low drift offset and
gain operation over –40∞C to +150∞C. Temperature compensation can accommodate a number of magnetic materials commonly
utilized in economic position sensor assemblies.
The transducer can be configured for specific signal gains to
meet various 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
signal is ratiometric to the positive supply rail in all configurations.
FUNCTIONAL BLOCK DIAGRAM
V
CC
TEMP REF
I
SOURCE
/2
AD22151
REF
OUT AMP
DEMODSWITCHES
Figure 1. Typical Bipolar Configuration with Low
(< –500 ppm) Compensation
REV. A
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registered trademarks are the property of their respective companies.
Figure 2. Typical Unipolar Configuration with
⬇
High (
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–2000 ppm) Compensation
AD22151–SPECIFICATIONS
(TA = 25ⴗC and V+ = 5 V, unless otherwise noted.)
Parameter Min Typ Max Unit
OPERATION
VCC Operating 4.5 5.0 6.0 V
ICC Operating 6.0 10 mA
INPUT
TC3 (Pin 3) Sensitivity/Volt 160 mV/G/V
V
Input Range
OUTPUT
1
2
CC
05± .
2
V
Sensitivity (External Adjustment, Gain = +1) 0.4 mV/G
Linear Output Range 10 90 % of V
Output Min 5.0 % of V
Output Max (Clamp) 93 % of V
CC
CC
CC
Drive Capability 1.0 mA
V
Offset @ 0 Gauss
Offset Adjust Range 5.0 95 % of V
CC
2
V
CC
Output Short Circuit Current 5.0 mA
ACCURACIES
Nonlinearity (10% to 90% Range) 0.1 % FS
Gain Error (Over Temperature Range) ± 1%
Offset Error (Over Temperature Range) ± 6.0 G
Uncompensated Gain TC (G
RATIOMETRICITY ERROR 1.0 %V/V
) 950 ppm
TCU
CC
3 dB ROLL-OFF (5 mV/G) 5.7 kHz
OUTPUT NOISE FIGURE (6 kHz BW) 2.4 mV/rms
PACKAGE 8-Lead SOIC
OPERATING TEMPERATURE RANGE –40 +150 ∞C
NOTES
1
–40∞C to +150∞C.
2
RL = 4.7 kW.
Specifications subject to change without notice.
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 V
Package Power Dissipation . . . . . . . . . . . . . . . . . . . . . . 25 mW
Storage Temperature . . . . . . . . . . . . . . . . . . . –50∞C to +160∞C
Output Sink Current, I
. . . . . . . . . . . . . . . . . . . . . . . . 15 mA
O
Magnetic Flux Density . . . . . . . . . . . . . . . . . . . . . . Unlimited
Model Range Description Option
AD22151YR –40∞C to +150∞C 8-Lead SOIC R-8
AD22151YR-REEL –40∞C to +150∞C 8-Lead SOIC R-8
ORDERING GUIDE
Temperature Package Package
Lead Temperature (Soldering 10 sec) . . . . . . . . . . . . . . 300∞C
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicated in the operational
sections of this specification is not implied. Exposure to the absolute maximum
rating conditions for extended periods may affect device reliability.
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although the
AD22151 features proprietary ESD protection circuitry, permanent damage may occur on devices
subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended
to avoid performance degradation or loss of functionality.
REV. A–2–
AD22151
TEMPERATURE – ⴗC
14
–4
–40
% GAIN
10 60 110 160
12
4
2
0
–2
10
6
8
–6
PIN CONFIGURATION
1
TC1
2
AD22151
TC2
TOP VIEW
3
TC3
(Not to Scale)
GND
4
AREA OF SENSITIVITY*
1
2
3
(Not to Scale)
4
*SHADED AREA REPRESENTS
MAGNETIC FIELD AREA OF
SENSITIVITY (20MILS ⴛ 20MILS)
POSITIVE B FIELD INTO TOP OF
PACKAGE RESULTS IN A POSITIVE
VOLTAGE RESPONSE
8
V
7
REF
6
GAIN
5
OUTPUT
8
7
6
5
CC
CIRCUIT OPERATION
The AD22151 consists of epi Hall plate structures located at the
center of the die. The Hall plates are orthogonally sampled by
commutation switches via a differential amplifier. The two
amplified Hall signals are synchronously demodulated to provide a
resultant offset cancellation (see Figure 3). The demodulated
signal passes through a noninverting amplifier to provide final
gain and drive capability. The frequency at which the output
signal is refreshed is 50 kHz.
0.005
0.004
0.003
0.002
0.001
0
OFFSET – V
–0.001
–0.002
–0.003
–0.004
140 –40120 100 80 60 40 20 0 –20
TEMPERATURE – ⴗC
PIN FUNCTION DESCRIPTIONS
Pin No. Description Connection
1Temperature Compensation 1 Output
2Temperature Compensation 2 Output
3Temperature Compensation 3 Input/Output
4Ground
5Output Output
6 Gain Input
7Reference Output
8 Positive Power Supply
“valleys” of the silicon crystal. Mechanical force on the sensor is
attributable to package-induced stress. The package material
acts to distort the encapsulated silicon, altering the Hall cell
gain by ± 2% and G
Figure 4 shows the typical G
by ± 200 ppm.
TCU
TCU
characteristic of the AD22151.
This is the observable alteration of gain with respect to temperature with Pin 3 (TC3) held at a constant 2.5 V (uncompensated).
If a permanent magnet source used in conjunction with the
sensor also displays an intrinsic TC (B
), it will require factoring
TC
into the total temperature compensation of the sensor assembly.
Figures 5 and 6 represent typical overall temperature/gain performance for a sensor and field combination (B
= –200 ppm).
TC
Figure 5 is the total drift in volts over a –40∞C to +150∞C temperature range with respect to applied field. Figure 6 represents
typical percentage gain variation from 25∞C. Figures 7 and 8
show similar data for a B
= –2000 ppm.
TC
Figure 3. Relative Quiescent Offset vs. Temperature
TEMPERATURE DEPENDENCIES
The uncompensated gain temperature coefficient (G
TCU
) of the
AD22151 is the result of fundamental physical properties associated with silicon bulk Hall plate structures. Low doped Hall
plates operated in current bias mode exhibit a temperature
relationship determined by the action of scattering mechanisms
and doping concentration.
The relative value of sensitivity to magnetic field can be altered
by the application of mechanical force upon silicon. The mechanism is principally the redistribution of electrons throughout the
REV. A
–3–
Figure 4. Uncompensated Gain Variation (from
25∞C) vs. Temperature
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