Integrated AMR Angle Sensor and Signal
Conditioner
Data Sheet
ADA4571
FEATURES
High precision 180° angle sensor
Maximum angular error of 0.5°
Analog sine and cosine outputs
Ratiometric output voltages
Low thermal and lifetime drift
SAR or Σ-Δ analog-to-digital converter (ADC) drive capable
Magnetoresistive (MR) bridge temperature compensation mode
Temperature range: −40°C to +150°C
EMI resistant
Fault diagnostics
VDD from 2.7 V to 5.5 V
Minimum phase delay
Qualified for automotive applications
Available in an 8-lead SOIC package
APPLICATIONS
Absolute position measurement (linear and angle)
Brushless dc motor control and positioning
Actuator control and positioning
Contactless angular measurement and detection
Magnetic angular position sensing
FUNCTIONAL BLOCK DIAGRAM
Figure 1.
GENERAL DESCRIPTION
The ADA4571 is an anisotropic magnetoresistive (AMR) sensor
with integrated signal conditioning amplifiers and ADC drivers.
The ADA4571 produces two analog outputs that indicate the
angular position of the surrounding magnetic field.
The ADA4571 consists of two die within one package, an AMR
sensor, and a fixed gain (G = 40 nominally) instrumentation
amplifier. The ADA4571 delivers clean and amplified cosine
and sine output signals related to the angle of a rotating
magnetic field. The output voltage range is ratiometric to the
supply voltage.
The sensor contains two Wheatstone bridges, at a relative angle
of 45° to one another. A rotating magnetic field in the x-y
sensor plane delivers two sinusoidal output signals with the
double frequency of the angle (α) between sensor and magnetic
field direction. Within a homogeneous field in the x-y plane,
the output signals are independent of the physical placement in
the z direction (air gap).
The ADA4571 is available in an 8-lead SOIC package.
COMPANION PRODUCTS
ADCs: AD7265, AD7266, AD7866, AD7902
Microconverter: ADuCM360
Current Sense Amplifier: AD8418A
Voltage Regulator Design Tool: ADIsimPower
Additional companion products on the ADA4571 product page
PRODUCT HIGHLIGHTS
1. Contactless angular measurement.
2. Measures magnetic field direction rather than field intensity.
3. Minimum sensitivity to air gap variations.
4. Large working distance.
5. Excellent accuracy, even for weak saturation fields.
6. Minimal thermal and lifetime drift.
7. Negligible hysteresis.
8. Single chip solution.
ADA4571
EMI
FILTER
EMI
FILTER
+G = 40
+
–
–
G = 40
DRIVER
DRIVER
AMR BRIDGE
SENSORS
TEMPERATURE SENSOR
BRIDG E DRIVE R
BIAS OSCILLATOR FAULT DETECTION
VTEMP
GC
VSIN
VCOS
PDGNDGND
VDD
12514-001
Rev. 0 Document Feedback
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Technical Support www.analog.com
ADA4571 Data Sheet
Rev. 0 | Page 2 of 21
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Companion Products ....................................................................... 1
Product Highlights ........................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Magnetic Characteristics ............................................................. 3
Electrical Characteristics ............................................................. 3
Absolute Maximum Ratings ............................................................ 7
Thermal Resistance ...................................................................... 7
ESD Caution .................................................................................. 7
Pin Configuration and Descriptions ...............................................8
Typical Performance Characteristics ..............................................9
Terminology .................................................................................... 13
Theory of Operation ...................................................................... 14
Application Information ................................................................ 16
Angle Calculation ....................................................................... 16
Connection to ECU ................................................................... 16
Mechanical Tolerances Diagrams ............................................ 18
Diagnostics .................................................................................. 19
Outline Dimensions ....................................................................... 21
Ordering Guide .......................................................................... 21
Automotive Products ................................................................. 21
REVISION HISTORY
10/14—Revision 0: Initial Version
Data Sheet ADA4571
SPECIFICATIONS
MAGNETIC CHARACTERISTICS
Table 1.
Parameter Value Unit Test Conditions/Comments
Magnetic Field Strength, HEXT 25 kA/m The stimulating magnetic field in the x-y sensor plane necessary to ensure the
minimum error as specified in Table 1 and Table 2
Maximum Magnetic Field Rotational
Frequency
50,000 rpm
Reference Position Error ±50 µm
Reference Angle Error ±2 Degrees
Reference position for y = 0 µm is the straight connection line of Pin 2 and Pin 7;
the x = 0 µm position is referred to the middle distance of the package top
Reference position for angle Φ = 0° is parallel to the straight connection line
of Pin 2 and Pin 7
ELECTRICAL CHARACTERISTICS
ADA4571WH
−40°C ≤ TA ≤ +150°C, VDD = 2.7 V to 5.5 V, CL = 10 nF to GND, RL = 200 kΩ to GND; angle inaccuracies referred to homogenous
magnetic field of 25 kA/m; output signals and offset voltages are related to the common-mode level of VDD/2, unless otherwise stated.
Table 2.
Parameter Symbol Test Conditions/Comments Min Typ Max Unit
ANGULAR PERFORMANCE
Angle Measurement Range 0 180 Degrees
Uncorrected Angular Error1 αUNCORR TA = −40°C ±5 Degrees
TA = 25°C ±5 Degrees
TA = 150°C ±5 Degrees
Single Point Calibration Angular
Error2, 3
αCAL TA = −40°C to +150°C, GC = GND ±0.7 Degrees
TA = −40°C to +150°C, GC = VDD ±0.7 Degrees
Dynamic Angular Error4 αDYNAMIC TA = −40°C to +150°C, rotation frequency =
2000 rpm
±0.1 ±0.5 Degrees
OUTPUT PARAMETERS
Amplitude VAMP
GC = GND TA = −40°C 63 75 % VDD
T
A
= 25°C
41
53
% V
DD
TA = 125°C 21 33 % VDD
TA = 150°C 18 30 % VDD
GC = VDD TA = −40°C 56 77 % VDD
TA = 25°C 52 72 % VDD
TA = 125°C 38 57 % VDD
TA = 150°C 35 55 % VDD
Output Voltage Range VO_SWING VSIN and VCOS, normal operation 7 93 % VDD
Output Voltage Low VOL VSIN or VCOS, broken bond wire detected 5 % VDD
Output Referred Offset Voltage VOFFSET GC = VDD 3.75 % VDD
GC = GND 3.75 % VDD
Amplitude Synchronism Error5 k −1 +1 % peak
Delay Time tDEL Rotation frequency = 30,000 rpm 2 µs
Phase Error6 ΦERR Rotation frequency = 30,000 rpm 0.8 Degrees
Orthogonality Error3 OE 0.05 Degrees
Output Noise VNOISE Bandwidth (BW) = 80 kHz, referred to
output (RTO)
500 µV rms
Output Series Resistance
R
O
Normal operation, PD = GND
60
Ω
PD = VDD 63 kΩ
Output −3 dB Cutoff Frequency3 f−3dB Amplifier BW, CL = 10 pF 100 kHz
Rev. 0 | Page 3 of 21
ADA4571 Data Sheet
Parameter Symbol Test Conditions/Comments Min Typ Max Unit
Power Supply Rejection3 PSRR Measured as output variation from VDD/2,
VDD = 2.7 V to 5.5 V, RL = 200 kΩ to GND,
GC = GND or VDD
80 dB
Output Short-Circuit Current ISC Short to GND per pin (VSIN, VCOS) 15 20 mA
Short to VDD per pin (VSIN, VCOS)
−15
−18
mA
Sensitivity SEN α1 = 0°, α2 = 135°, TA = 25°C 52 mV/°
POWER SUPPLY
Supply Voltage VDD 2.7 5.5 V
Quiescent Supply Current ISY PD = GND, GC = GND, no load 3.5 4.5 6.5 mA
PD = GND, GC = VDD, no load 7 mA
PD = VDD, no load 15 µA
Power-Up Time tPWRUP To 98% of desired output level after VDD was
reached
150 µs
To 98% of desired output level after PD cycling
100
µs
DIGITAL INPUTS
Input Bias Current (GC)
I
B_GC
For GC mode control pin, GC = GND
30
µA
For GC mode control pin, GC = VDD 3 µA
Input Bias Current (PD) IB_PD For PD pin, PD = GND 3 µA
For PD pin, PD = VDD 30 µA
Input Voltage (GC and PD)
High VIH 1.4 V
Low VIL 0.35 V
TEMPERATURE SENSOR
Error Over Temperature TERR 5 °C
Temperature Voltage Range
T
RANGE
T
A
= −40°C to +150°C
0
82
% V
DD
Temperature Coefficient TCO 3.173 mV/V/°C
VTEMP Output Voltage TA = 25°C 18 40 % VDD
VTEMP Output Impedance Buffered output 50 Ω
VTEMP Load Capacitance Optional load capacitance 0 22 nF
VTEMP Short-Circuit Current
I
SC_VTEMP
Short-circuit to VDD or GND
2
mA
LOAD CAPACITOR
External Load Capacitance CL Between VSIN to GND and VCOS to GND;
solder close to package
10 nF
1 αUNCORR is the total mechanical angular error after arctan computation. This parameter is 100% production tested at 25°C and 150°C. This error includes all sources of
error over temperature before calibration. Error components such as offset, amplitude synchronism, amplitude synchronism drift, thermal offset drift, phase error,
hysteresis, orthogonality error, and noise are included.
2 αCAL is the total mechanical angular error after arctan computation. This error includes all sources of error over temperature after an initial offset (nulling) is performed
at TA = 25°C. Error components such as amplitude synchronism drift, amplifier gain matching, thermal offset drift, phase error, hysteresis, orthogonality error, and
noise are included.
3 Guaranteed through characterization.
4 αDYNAMIC is the total mechanical angular error after arctan computation. This parameter is 100% production tested. This error includes all sources of error over
temperature after a continuous background calibration is performed to correct offset and amplitude synchronism errors. Error components such as phase error,
hysteresis, orthogonality error, noise, and lifetime drift are included.
5 Peak-to-peak amplitude mismatch. k = 100 × VSIN/VCOS.
6 Rotation frequency dependent phase error, after offset correction, amplitude calibration, and arctan calculation.
Rev. 0 | Page 4 of 21
Data Sheet ADA4571
ADA4571B
−40°C ≤ TA ≤ +125°C, VDD = 2.7 V to 5.5 V, CL = 10 nF to GND, RL = 200 kΩ to GND; angle inaccuracies referred to homogenous
magnetic field of 25 kA/m; output signals and offset voltages are related to the common-mode level of VDD/2, unless otherwise stated.
Table 3.
Parameter Symbol Test Conditions/Comments Min Typ Max Unit
ANGULAR PERFORMANCE
Angle Measurement Range 0 180 Degrees
Uncorrected Angular Error1 αUNCORR TA = −40°C ±3 Degrees
TA = 25°C ±3 Degrees
TA = 125°C ±4 Degrees
Single Point Calibration Angular
Error2, 3
αCAL TA = −40°C to +125°C, GC = GND ±0.5 Degrees
TA = −40°C to +125°C, GC = VDD ±0.5 Degrees
Dynamic Angular Error4 αDYNAMIC TA = −40°C to +125°C, rotation frequency =
2000 rpm
0.1 ±0.4 Degrees
Angular Inaccuracy3, 5 ∆α After end of line (EOL) calibration for offset
voltage error and amplitude synchronism at
TA = −40°C to +125°C (only 180° range)
0.05 Degrees
OUTPUT PARAMETERS
Amplitude
V
AMP
GC = GND TA = −40°C 63 75 % VDD
TA = 25°C 41 53 % VDD
TA = 125°C 21 33 % VDD
GC = VDD TA = −40°C 56 77 % VDD
TA = 25°C 52 72 % VDD
TA = 125°C 38 57 % VDD
Output Voltage Range VO_SWING VSIN and VCOS, normal operation 7 93 % VDD
Output Voltage Low VOL VSIN or VCOS, broken bond wire detected 3.75 % VDD
Output Referred Offset Voltage VOFFSET GC = VDD 3.75 % VDD
GC = GND 3.75 % VDD
Amplitude Synchronism Error6 k −0.75 +0.75 % peak
Delay Time tDEL Rotation frequency = 30,000 rpm 2 µs
Phase Error7 ΦERR Rotation frequency = 30,000 rpm 0.8 Degrees
Orthogonality Error
3
OE
0.05
Degrees
Output Noise VNOISE BW = 80 kHz, RTO 500 µV rms
Output Series Resistance RO Normal operation, PD = GND 50 Ω
PD = VDD 63 kΩ
Output −3 dB Cutoff Frequency3 f−3dB Amplifier BW, CL = 10 pF 100 kHz
Power Supply Rejection3 PSRR Measured as output variation from VDD/2,
VDD = 2.7 V to 5.5 V, RL = 200 kΩ to GND,
GC = GND or VDD
80 dB
Output Short-Circuit Current ISC Short to GND per pin (VSIN, VCOS) 15 20 mA
Short to VDD per pin (VSIN, VCOS) −15 −18 mA
Sensitivity SEN α = 0° and 135°, TA = 25°C 52 mV/°
POWER SUPPLY
Supply Voltage VDD 2.7 5.5 V
Quiescent Supply Current ISY PD = GND, GC = GND, no load 3.5 4.5 6 mA
PD = GND, GC = VDD 6.5 mA
PD = VDD, no load 12.5 µA
Power-Up Time tPWRUP To 98% of desired output level after VDD was
reached
150 µs
To 98% of desired output level after PD cycling 100 µs
Rev. 0 | Page 5 of 21
ADA4571 Data Sheet
Parameter Symbol Test Conditions/Comments Min Typ Max Unit
DIGITAL INPUTS
Input Bias Current (GC) IB_GC For GC mode control pin, GC = GND 30 µA
For GC mode control pin, GC = VDD 3 µA
Input Bias Current (PD) IB_PD For PD pin, PD = GND 3 µA
For PD pin, PD = V
DD
30
µA
Input Voltage (GC and PD)
High VIH 1.4 V
Low VIL 0.35 V
TEMPERATURE SENSOR
Error Over Temperature TERR 5 °C
Temperature Voltage Range TRANGE TA = −40°C to +125°C 0 69 % VDD
Temperature Coefficient TCO 3.173 mV/V/°C
VTEMP Output Voltage TA = 25°C 18 40 % VDD
VTEMP Output Impedance
Buffered output
50
Ω
VTEMP Load Capacitance Optional load capacitance 0 22 nF
VTEMP Short-Circuit Current ISC_VTEMP Short-circuit to VDD or GND 2 mA
LOAD CAPACITOR
External Load Capacitance CL Between VSIN to GND and VCOS to GND;
solder close to package
10 nF
1 αUNCORR is the total mechanical angular error after arctan computation. This parameter is 100% production tested at 25°C and 150°C. This error includes all sources of
error over temperature before calibration. Error components such as offset, amplitude synchronism, amplitude synchronism drift, thermal offset drift, phase error,
hysteresis, orthogonality error, and noise are included.
2 αCAL is the total mechanical angular error after arctan computation. This error includes all sources of error over temperature after an initial offset (nulling) is performed
at TA = 25°C. Error components such as amplitude synchronism drift, amplifier gain matching, thermal offset drift, phase error, hysteresis, orthogonality error, and
noise are included.
3 Guaranteed through characterization.
4 αDYNAMIC is the total mechanical angular error after arctan computation. This parameter is 100% production tested. This error includes all sources of error over
temperature after a continuous background calibration is performed to correct offset and amplitude synchronism errors. Error components such as phase error,
hysteresis, orthogonality error, noise, and lifetime drift are included.
5 Angular speed <300 rpm. Limited to 180° rotation. The value is calculated only with the third and fifth harmonics of the spectrum of output signal amplitude by the
ideal homogeneous field.
6 Peak-to-peak amplitude mismatch. k = 100 × VSIN/VCOS.
7 Rotation frequency dependent phase error, after offset correction, amplitude calibration, and arctan calculation.
Rev. 0 | Page 6 of 21
Data Sheet ADA4571
ABSOLUTE MAXIMUM RATINGS
Table 4.
Parameter Rating
Operating Temperature −40°C to +150°C
Storage Temperature
−65°C to +150°C
Supply Voltage (VDD)1 −0.3 V to +6 V
Output Short-Circuit Duration to GND or VDD Indefinite
VTEMP Short-Circuit to GND or VDD Indefinite
ESD
Human Body Model (HBM)2 4000 V
Machine Model (MM)3 300 V
Charge Device Model (CDM)4 1250 V
1 GC or PD at VDD + 0.3 V.
2 Applicable standard: JESD22-C101.
3 Applicable standard: JESD22-A115.
4 Applicable standard: ESDA/JEDEC JS-001-2011.
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
THERMAL RESISTANCE
θJA is specified for the worst case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 5. Thermal Resistance
Package Type θJA Unit
8-Lead SOIC 120 °C/W
ESD CAUTION
Rev. 0 | Page 7 of 21
ADA4571 Data Sheet
PIN CONFIGURATION AND DESCRIPTIONS
Figure 2. Pin Configuration
Table 6. Pin Function Descriptions
Pin No. Mnemonic Description
1 GC Gain Control Mode Enable
2 VCOS Analog Cosine Output
3 GND Ground
4
VSIN
Analog Sine Output
5 VTEMP Temperature Output
6 GND Ground
7 VDD Supply Pin
8 PD Power-Down Pin, Active High
GC
1
VCOS
2
GND
3
VSIN
4
PD
8
VDD
7
GND
6
VTEMP
5
12514-002
ADA4571
(No t t o Scal e)
TOP VIEW
Rev. 0 | Page 8 of 21
Data Sheet ADA4571
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 3. Raw Output Waveforms, VDD = 5 V, GC = On, T = 25°C
Figure 4. Error Waveform After Offset Correction, VDD = 5 V, GC = On
Figure 5. Dynamic Angular Error, VDD = 5.5 V, GC = On
Figure 6. Dynamic Angular Error, VDD = 5.5 V, GC = Off
Figure 7. Dynamic Angular Error, VDD = 2.7 V, GC = On
Figure 8. Dynamic Angular Error, VDD = 2.7 V, GC = Off
0
1
2
3
4
5
090 180 270 360
OUTPUT AMPLIT UDE (V)
RELATIVE M E CHANICALANGL E ( Degrees)
12514-010
–0.2
–0.1
0
0.1
0.2
090 180 270 360
ERROR (Degrees)
MECHANICALANGL E ( Degrees)
12514-011
12514-012
0
5
10
15
20
25
30
35
40
00.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
COUNT (%)
DYNAMIC ANGULAR ERROR (Degrees)
–40°C
+25°C
+125°C
+150°C
12514-013
0
5
10
15
20
25
30
35
40
00.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
COUNT (%)
DYNAMIC ANGULAR ERROR (Degrees)
–40°C
+25°C
+125°C
+150°C
12514-014
0
5
10
15
20
25
30
35
00.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
COUNT (%)
DYNAMIC ANGULAR ERROR (Degrees)
–40°C
+25°C
+125°C
+150°C
12514-015
0
5
10
15
20
25
30
35
00.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
COUNT (%)
DYNAMIC ANGULAR ERROR (Degrees)
–40°C
+25°C
+125°C
+150°C
Rev. 0 | Page 9 of 21
ADA4571 Data Sheet
Figure 9. Uncorrected Angular Error, VDD = 5.5 V, GC = On
Figure 10. Uncorrected Angular Error, VDD = 5.5 V, GC = Off
Figure 11. Uncorrected Angular Error, VDD = 2.7 V, GC = On
Figure 12. Uncorrected Angular Error, VDD = 2.7 V, GC = Off
Figure 13. Single Point Calibration Angular Error, VDD = 5.5 V, GC = On
Figure 14. Single Point Calibration Angular Error, VDD = 5.5 V, GC = Off
12514-016
0
5
10
15
20
25
30
35
40
00.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
COUNT (%)
UNCORRECTED ANGUL AR E RROR (Degrees)
–40°C
+25°C
+125°C
+150°C
12514-017
0
5
10
15
20
25
30
35
40
00.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
COUNT (%)
UNCORRECTED ANGUL AR E RROR (Degrees)
–40°C
+25°C
+125°C
+150°C
12514-018
0
5
10
15
20
25
30
35
00.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
COUNT (%)
UNCORRECTED ANGUL AR E RROR (Degrees)
–40°C
+25°C
+125°C
+150°C
12514-019
0
5
10
15
20
25
30
35
00.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
COUNT (%)
UNCORRECTED ANGUL AR E RROR (Degrees)
–40°C
+25°C
+125°C
+150°C
0
0.2
0.4
0.6
0.8
1.0
1.2
–40 040 80 120
ERROR (Degrees)
TEMPERATURE ( °C)
12514-020
0
0.2
0.4
0.6
0.8
1.0
1.2
–40 040 80 120
ERROR (Degrees)
TEMPERATURE ( °C)
12514-021
Rev. 0 | Page 10 of 21
Data Sheet ADA4571
Figure 15. Single Point Calibration Angular Error, VDD = 2.7 V, GC = On
Figure 16. Single Point Calibration Angular Error, VDD = 2.7 V, GC = Off
Figure 17. Supply Current (ISY) vs. Voltage (VDD), T = 25°C
Figure 18. Supply Current (ISY) vs. Temperature, VDD = 5 V
Figure 19. Supply Current (ISY) vs. Temperature, VDD = 3 V
Figure 20. Power-Down Current (IPD) vs. Temperature
0
0.2
0.4
0.6
0.8
1.0
1.2
–40 040 80 120
ERROR (Degrees)
TEMPERATURE ( °C)
12514-022
0
0.2
0.4
0.6
0.8
1.0
1.2
–40 040 80 120
ERROR (Degrees)
TEMPERATURE ( °C)
12514-023
3
4
5
6
7
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
I
SY
(mA)
V
DD
(V)
12514-024
TEMPERATURE ( °C)
4.6
4.8
5.0
5.2
5.4
5.6
5.8
–40 040 80 120
I
SY
(mA)
GC OFF (mA)
GC O N (mA)
12514-025
TEMPERATURE ( °C)
–40 040 80 120
3.6
3.8
4.0
4.2
4.4
4.6
I
SY
(mA)
GC OFF (mA)
GC O N (mA)
12514-026
0
2
4
6
8
10
TEMPERATURE ( °C)
–40 040 80 120
I
PD
(µA)
5V
3V
12514-027
Rev. 0 | Page 11 of 21
ADA4571 Data Sheet
Figure 21. VTEMP Output Voltage vs. Temperature
Figure 22. Amplitude Synchronism (% k)
Figure 23. Output Voltage (VSIN and VCOS) Peak-to-Peak vs.
Temperature (% VDD)
Figure 24. Angular Error Delay vs. RPM (Mechanical)
0
10
20
30
40
50
60
70
80
90
100
–40 040 80 120
VTEMP (%V
DD
)
TEMPERATURE (°C)
12514-028
0
2
4
6
8
10
12
14
16
18
20
–1.00 –0.75 –0.50 –0.25 00.25 0.50 0.75 1.00
COUNT (%)
AMPLITUDE MISMATCH (%)
12514-029
0
10
20
30
40
50
60
70
80
90
100
–40 040 80 120
V
OUT
(V p-p %V
DD
)
TEMPERATURE ( °C)
V
OUT
p-p GC OFF
V
OUT
p-p GC ON
12514-030
–1.0
–0.9
–0.8
–0.7
–0.6
–0.5
–0.4
–0.3
–0.2
–0.1
0
300 3000 30000
ANGULAR ERRO R DE LAY (Degrees)
RPM ( M echanical )
ERROR –40°C
ERROR + 25°C
ERROR + 150°C
12514-031
Rev. 0 | Page 12 of 21
Data Sheet ADA4571
TERMINOLOGY
Reference Position Error
The reference position error is the absolute mounting position
deviation of the sensor from its nominal placement. The
reference position for Y = 0 µm is the straight connection line of
Pin 2 and Pin 7. The X = 0 µm position is referred to the middle
distance of the package top. The position accuracies are within
a precision of ±0.05 mm (±50 µm) in both the X and Y
direction.
Reference Angle Error
The reference angle error is the absolute mounting rotation
deviation of the sensor from its nominal placement. Marking
the position for angle Φ= 0° position is referred parallel to the
straight connection line of Pin 2 and Pin 7.
Figure 25. Bonding Arrangement and Sensor Alignment in Package
Output Amplitude Synchronism Error
The output amplitude matching error (k) is defined as the
relationship between both output channel amplitudes at
continuously rotating magnetic excitation of the MR sensor
mathematically expressed as
k = 100% × VSIN_P-P/VCOS_P-P
Uncorrected Angular Error
The uncorrected angular error is defined as the maximum
deviation from an ideal angle reading, when calculating the
angle from VSIN and VCOS without offset calibration.
Single Point Calibration Angular Error
The single point calibration angular error is defined as the
maximum deviation from an ideal angle reading, when
calculating the angle from VSIN and VCOS after an initial
calibration for offset voltage at TA = 25°C.
Dynamic Angular Error
The dynamic angular error is defined as the maximum
deviation from an ideal angle reading, when calculating the
angle from VSIN and VCOS while a continuous offset calibration is
taken into account.
Phase Error
The phase error (ΦERR) is defined as the rotation frequency
dependent error due to bandwidth limitation of the instrumen-
tation amplifiers. VSIN and VCOS are impacted by the amplifier
propagation delay, referred to the actual angle direction of the
rotating magnetic field. The typical characteristics value can be
used for a first-order compensation of this error on very high
rotations per minute. For low rotational speed systems, this error
component is negligible and no compensation is necessary.
GC
1
VCOS
2
GND
3
VSIN
4
PD
8
VDD
7
GND
6
VTEMP
5
12514-006
Rev. 0 | Page 13 of 21
ADA4571 Data Sheet
THEORY OF OPERATION
The ADA4571 is an AMR sensor with integrated signal
conditioning amplifiers and ADC drivers. The ADA4571
produces two analog outputs, sine and cosine, which indicate
the angular position of the surrounding magnetic field.
The AMR sensing element is designed and manufactured by
Sensitec GmbH.
Figure 27 shows the sine channel, consisting of an AMR sensor
element and the supporting functions for control, filtering,
buffering, and signal amplification. A reference voltage that is
proportional to the supply voltage is generated and it controls
the supply voltage of the sensor bridges. For noise and
electromagnetic compatibility (EMC) suppression purposes, the
bridge supply is low-pass filtered. The bridge output voltages
are amplified by a constant factor (G = 40, GC mode disabled)
and buffered. The single-ended outputs are biased around a
common-mode voltage of VDD/2 and are capable of driving the
inputs of an external ADC referenced to the supply voltage.
For optimum use of the ADC input range, the cosine and sine
output voltages track the supply voltage ensuring a ratiometric
configuration. To achieve high signal performance both output
signals are carefully matched in both amplitude and phase. The
amplifier bandwidth is sufficient to ensure low phase delay at
maximum specified rotation speed.
Electromagnetic interference (EMI) filters at the sensor outputs
and between the first and second stages reject unwanted noise
and interference from appearing in the signal band.
The architecture of the instrumentation amplifier consists of
precision, low noise, zero drift amplifiers that feature a proprietary
chopping technique. This chopping technique offers a low input
offset voltage of 0.3 µV typical and an input offset voltage drift
of 0.02 µV/°C typical. The zero drift design also features
chopping ripple suppression circuitry, which removes glitches
and other artifacts caused by chopping.
Offset voltage errors caused by common-mode voltage swings
and power supply variations are also corrected by the chopping
technique, resulting in a dc common-mode rejection ratio that
is greater than 150 dB. The amplifiers feature low broadband
noise of 22 nV/√Hz and no 1/f noise component. These features
are ideal for amplification of the low level AMR bridge signals
for high precision sensing applications.
In addition, extensive diagnostics are integrated on-chip to self
check sensor and IC conditions.
Figure 26. Direction of Homogeneous Magnetic Field for α = 0°
Figure 27. Detailed Internal Diagram of the ADA4571 Sine Channel
1
2
3
4
8
7
6
5
ADA4571
(No t t o Scal e)
TOP VIEW
12514-004
+
–
+
–
–
+
–
+
VDD
VDD/2
VDD
VDD
VTEMP
3.3kΩ
3.3kΩ
50Ω
20pF
62.7pF
VSIN
AMR
BRIDGE
ADA4571
62.7pF
12514-005
Rev. 0 | Page 14 of 21
Data Sheet ADA4571
Figure 28. Typical Output Waveforms; Sine and Cosine vs. Magnetic Angle
93% V DD
VCOS
VSIN
50% V DD
7% VDD
MAGNETIC ANGLE, α (Degrees)
090 180 270 360
VOFFSET
DIAGNOSTIC
BAND
DIAGNOSTIC
BAND
LINEAR
REGION
V p-p
12514-003
Rev. 0 | Page 15 of 21
ADA4571 Data Sheet
APPLICATIONS INFORMATION
The integrated AMR sensor is designed for applications with a
separate processing IC or electronic control unit (ECU) containing
an ADC with references connected to the supply voltage. With
the ADC input resolution related to VDD in the same way as the
AMR sensor output, the system is inherently ratiometric and the
signal dependency on supply voltage changes are minimized.
ANGLE CALCULATION
To calculate angle from the output of the AMR device, use the
trigonometric function arctangent2. The arctangent2 function
is a standard arctangent function with additional quadrant
information to extend the output from the magnetic angle range
of −90° to +90° to the magnetic angle range of −180° to +180°.
Because of the sensing range of AMR technology, this
calculated magnetic angle repeats over each pole of the magnet.
For a simple dipole magnet, the following equation reports
absolute angle over 180° mechanical:
2
)arctan(
COS
SIN
V
V
=
α
CONNECTION TO ECU
Because of the limited driving capability of the ADA4571
output, minimize the length of printed circuit board (PCB)
traces between the ADA4571 and other IC. Shielding of the
signal lines is recommended. Match the load capacitors and
resistors for best angular accuracy. Add bandwidth limitation
filters related to the sampling frequency of the system in front
of the ADC inputs to reduce noise bandwidth.
In Figure 29, the load resistors on VCOS and VSIN are
representing the input load of the filter and the ADC. The
processor may be used for arctan and offset calculations, offset
storage, and additional calibration.
VTEMP Output Pin
A proportional to absolute temperature circuit provides a
voltage output at the VTEMP pin for temperature monitoring
or temperature calibration purposes. The output voltage is
ratiometric to the supply voltage enabling the interface with an
ADC that uses the supply voltage to generate the reference
voltage. This pin must be left open when not in use.
To achieve maximum accuracy from the VTEMP output
voltage, perform an initial calibration at a known, controlled
temperature. Then, use the following equation to extract
temperature information:
VTEMP
CO
CAL
DD
CAL
DD
TEMP
VTEMP
TC
T
T
V
V
V
V
T
×
=
–
–
where:
TVTEMP is the calculated temperature (°C) from the VTEMP
output voltage.
VTEMP is the VTEMP output voltage during operation.
VDD is the supply voltage.
VCAL is the VTEMP output voltage during calibration at a
controlled temperature.
TCAL is the controlled temperature during calibration.
TCO is the temperature coefficient of the internal circuit; see the
Specifications section for the exact value.
Gain Control Mode
Gain control (GC) enable mode can be activated by switching
the GC pin to the VDD pin. In this mode, the AMR bridge
sensor amplitude outputs are compensated to reduce
temperature variation. This results in higher and controlled
output voltage levels, boosting system dynamic range and
easing the system design task. If the GC pin is left floating, a
weak pull-up resistor ensures that the GC mode is enabled as a
default condition. The GC mode can also be used as a sensor
self diagnostic by comparing the sine and cosine amplitude
outputs when enabled and disabled, such as radius check. In the
event that the radius does not change, it indicates a gross failure
in the IC.
Power-Down Mode
Power-down mode can be activated by switching the PD pin to
the VDD pin. Within this mode, the device shuts down and its
output pins are set to high impedance to avoid current
consumption across the load resistors. The VTEMP output is
connected to ground through a pull-down resistor. Power-down
mode can be entered with GC = VDD or GC = GND. An internal
pull-down resistor ensures that the device remains active if the
PD pin is left floating.
Rev. 0 | Page 16 of 21
Data Sheet ADA4571
Figure 29. Typical Application Diagram with Separate Processor and Data Conversion
Power Consumption
Worst case quiescent power occurs when the supply current
runs at its specified maximum of 7 mA and the ADA4571 is run
at the maximum VDD of 5.5 V, giving a worst case quiescent
power of 38.5 mW.
The power consumption is dependent on VDD, temperature,
load resistance (RL), load capacitance (CL), and frequency of the
rotating magnetic field. It is recommended to refer RL and CL to
ground. The output voltages are protected against short circuit
to the VDD pin or ground by current limitation within the
given time duration. Placing the device 180° rotated into the
socket may lead to damages if the supply current is not limited
to 100 mA.
Offset of Signal Outputs
The single-ended output signals are referenced to VDD/2
generated internally on-chip. Offsets originate from matching
inaccuracies and other imperfections during the production
process. For tight tolerances, it is required to match the external
loads for VSIN and VCOS to each other. For ESD and EMC
protection, the outputs contain a series resistance of 50 Ω. The
influence of this series resistance is minimized with a large
output load resistance.
Signal Dependence on Air Gap Distance
The IC measures the direction of the external magnetic field
within its x-y plane. The result is widely independent of the
field strength as long as it is above the specified minimum value
of 25 kA/m. Within a homogeneous field in x-y direction, the
result is independent of its placement in z direction (air gap).
The nominal z distance of the internal x-y plane to the top
surface of the plastic package is 0.400 mm.
ADA4571
EMI
FILTER
EMI
FILTER
+G = 40
+
–
–
G=40
DRIVER
DRIVER
AMR BRI DGE
SENSORS
TEMPERATURE SENSOR
BRIDG E DRIVE R
BIAS OSCILLATOR FAULT DETECTION
VTEMP
GC
VSIN
VCOS
PDGND
GND
VDD
VDD
RLO4 CLO4
Σ-Δ
ADC
MICROPROCESSOR
VDD
CLO2
RLO2
CLO3
RLO3
CLO1
RLO1
Σ-Δ
ADC
12514-007
Rev. 0 | Page 17 of 21
ADA4571 Data Sheet
MECHANICAL TOLERANCES DIAGRAMS
Figure 30. Mechanical Drawing of the ADA4571
AMR SENSING ELEMENT
1.400
1.250
1.100
0.475
0.400
0.325
SEATING PLANE
C
0.10 C
12514-035
Figure 31. Cross Sectional View of the ADA4571
0.25 C A B
0.25 C A
0.50 C B
M
SENSING ELEMENT
CENTER
NOTES 5, 6
NOTES 3, 6, 7
NOTE 2
NOTE 4
SEATING PLANE
LEAD TIPS
ALL LEADS
2.00
1.95
1.90
0.854
0.487
0.437
0.387
4
1
85
A
B
C
4.00
3.90
3.80
3.10
3.00
2.90 6.20
6.00
5.80
5.00
4.90
4.80 2.50
2.45
2.40
12514-034
0.10 C
1.27
NOTES
1. DIMENSIONS ARE IN MILLIMETERS.
2. M AX I MUM SE NS OR RO TAT ION.
3. THIS DIMENSION AND TRUE POSITION SPECIFY THE LOCATION OF THE CENTER
OF T HE SENSING ELEMENT W I T H RESPECT TO T HE CENTER OF THE PACKAGE.
THE CENTER OF THE SENSING ELEMENT IS ALIGNED WITH THE EDGES OF
LE AD 2 AND LEAD 7.
4. THE CENTER OF THE SENSING ELEMENT IS ALIGNED WITH THE CENTER LINE
OF THE P ACKAGE ( DATUM B) .
5. THE LEAD WIDTH DIMENSION IS TOLERANCED MORE TIGHTLY THAN ON
THE R8 PACKAGE OUT LI NE DRAWI NG. THI S DIMENS IO N IS M E AS URED AT
THE FOOT OF THE LEAD (NO FLASH, BURRS).
6. DO E S NOT INCL UDE M OL D FLAS H, DAMBAR P ROT RUS IONS , O R BURRS .
7. M OLD BODY WI DTH AND LE NGT H DIME NS IONS DO NO T I NCLUDE MOL D FL AS H,
OFFSETS, OR MOLD GATE PROTRUSIONS.
8. REFER TO THE R8 P ACKAGE O UTL INE DRAWING F OR DI M E NS IONS NOT S HOW N HE RE .
2° M AX
Rev. 0 | Page 18 of 21
Data Sheet ADA4571
DIAGNOSTICS
Radius Calculation
The VSIN and VCOS outputs can be used to calculate a radius
value. These outputs have a fixed 90° phase relationship and
therefore the calculated radius value remains in a predictable,
predetermined range that varies with the temperature of the
device independent of the current magnetic field direction. This
radius, VRAD, can be used to validate the VSIN and VCOS readings
in the ECU. When the calculated radius is no longer within the
acceptable bounds, a fault may occur in the system. To calculate
radius, use the following formula:
22 )
2
()
2
(DD
COS
DD
SINRAD V
V
V
VV −+−=
It is important to perform offset calibration before calculating
the radius.
Figure 32 shows the allowable radius values when GC mode is
enabled and Figure 33 shows the allowable radius values when
GC mode is disabled. The maximum and minimum VRAD values
are calculated based on the allowable amplitude range for VSIN
and VCOS, over the entire operating temperature of the device as
specified in the Specifications section. This range is represented
by the shaded region in Figure 32 and Figure 33.
Typical VRAD values for −40°C, +25°C, +125°C, and +150°C are
indicated as well.
Figure 32. GC On Radius Values
Figure 33. GC Off Radius Values
Monitoring of the VTEMP pin can allow an even tighter range
for radius length at the known temperature. See the
Specifications section and the Typical Performance
Characteristics section for exact values and output amplitude
specifications at each temperature.
Broken Bond Wire Detection
The ADA4571 includes circuitry to detect broken bond wire
conditions between the AMR sensor and the instrumentation
amplifier. The detection circuitry consists of current sources
and window comparators placed on the signal connections
between the AMR sensor and the ASIC. The purpose of the
current sources is to pull the signal node outside of the normal
operating region in the event of an open bond wire between the
AMR sensor and the ASIC. The purpose of the window
comparators is to detect when the signal from the AMR sensor
is outside of the normal operating region. When the comparators
detect that the signal nodes are outside the normal operating
region, the circuit pulls the VSIN and/or VCOS node to ground
to indicate the fault to the host controller.
In addition to the active circuitry, there are applications
recommendations, such as the utilization of pull-up and pull-
down resistors, which detect broken bond wires by pulling
nodes outside of the defined operating regions. A broken bond
wire at VTEMP, VCOS, and VSIN interrupts the corresponding
outputs. To ensure that the output enters into a known state if
there is a broken bond wire on these pins, connect a 200 kΩ
pull-down resistor at these pins. Pulling these nodes outside of
the normal operating region signals a fault to the host
controller.
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
0
5
VCOS MAG NIT UDE ( %V DD)
GC ON
VSIN MAGNIT UDE ( %V DD)
–40°C
+25°C
+125°C
+150°C
VSIN
VCOS
VCOS
VSIN
VRAD
12514-101
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
0
5
VCOS MAG NIT UDE ( %V DD)
GC OFF
VSIN MAGNIT UDE ( %V DD)
–40°C
+25°C
+125°C
+150°C
VSIN
VCOS
VCOS
VSIN
VRAD
12514-100
Rev. 0 | Page 19 of 21
ADA4571 Data Sheet
Short-Circuit Condition to GND or VDD
In the event of a short-circuit condition, the output voltages are
pulled to the GND or VDD pin.
Short-Circuit Between Sine and Cosine Sensor Outputs
In the event of a short-circuit between sensor outputs, the IC
output voltages are tied to the output common-mode voltage. A
gross angular error is detected in the microcontroller.
Figure 34. Output Span Classification During Short-Circuit Diagnostic Condition
Table 7. Diagnostic Cases
Fault Description Output Conditions Alert
Broken Bond Wire Between the
Internal MR Sensor and the ASIC
Broken bond wire detection is activated; the
broken channel(s), VSIN or VCOS, are pulled to
ground
Diagnostic region violation
Broken Bond Wire at the PD Pin Device remains functional No alert
Broken Bond Wire at the GC Pin Gain control is activated Possible change in output amplitude
Output Short-Circuit to GND Shorted channel is pulled to ground Diagnostic region violation
Output Short-Circuit to VDD Shorted channel is pulled to VDD Diagnostic region violation
100%
93%
OUTPUT LEVEL
LINEAR REGION
SHORT- CIRCUI T DI AGNOS TI C BAND ( HIG H)
SHORT- CIRCUI T DI AGNOS TI C BAND ( LO W)
7%
0%
12514-009
Rev. 0 | Page 20 of 21
Data Sheet ADA4571
Rev. 0 | Page 21 of 21
OUTLINE DIMENSIONS
Figure 35. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model1, 2 Temperature Range Package Description Package Option
ADA4571WHRZ-R7 −40°C to +150°C 8-Lead SOIC_N, 7” Tape and Reel R-8
ADA4571BRZ −40°C to +125°C 8-Lead SOIC_N R-8
ADA4571BRZ-RL −40°C to +125°C 8-Lead SOIC_N, 13” Tape and Reel R-8
ADA4571BRZ-R7 −40°C to +125°C 8-Lead SOIC_N, 7” Tape and Reel R-8
1 Z = RoHS Compliant Part.
2 W = Qualified for Automotive Applications.
AUTOMOTIVE PRODUCTS
The ADA4571WHRZ model is available with controlled manufacturing to support the quality and reliability requirements of automotive
applications. Note that this automotive model may have specifications that differ from the commercial models; therefore, designers
should review the Specifications section of this data sheet carefully. Only the automotive grade products shown are available for use in
automotive applications. Contact your local Analog Devices account representative for specific product ordering information and to
obtain the specific Automotive Reliability reports for these models.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
COMPLIANT TO JEDEC STANDARDS MS-012-AA
012407-A
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40 (0.0157)
0.50 (0.0196)
0.25 (0.0099) 45°
8°
0°
1.75 (0.0688)
1.35 (0.0532)
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0040)
4
1
85
5.00 (0.1968)
4.80 (0.1890)
4.00 (0.1574)
3.80 (0.1497)
1.27 (0.0500)
BSC
6.20 (0.2441)
5.80 (0.2284)
0.51 (0.0201)
0.31 (0.0122)
COPLANARITY
0.10
©2014 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D12514-0-10/14(0)
