A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
Discontinued Product
This device is no longer in production. The device should not be
purchased for new design applications. Samples are no longer available.
Date of status change: December 5, 2018
Recommended Substitutions:
For existing customer transition, and for new customers or new applications, refer to the A1335LLETR-T.
NOTE: For detailed information on purchasing options, contact your
local Allegro field applications engineer or sales representative.
Allegro MicroSystems reserves the right to make, from time to time, revisions to the anticipated product life cycle plan for a
product to accommodate changes in production capabilities, alternative product availabilities, or market demand. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems assumes no responsibility for
its use; nor for any infringements of patents or other rights of third parties which may result from its use.
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
FEATURES AND BENEFITS
•
•
•
•
•
•
•
•
•
•
360° contactless high resolution angle position sensor
CVH (Circular Vertical Hall) technology
Digital I2C output
Refresh Rate: 32 µs, 12-bit resolution
Automotive temperature range -40 to 85C as well as -40
to 125C
Two types of linearization schemes offered: harmonic
linearization and segmented linearization
Linearization features enable use in off-axis applications
EEPROM with Error Correction Control (ECC) for
trimming calibration
1 mm thin (TSSOP-14) package
Automatic calibration features maintain angle accuracy
over airgap
PACKAGE: 14-pin TSSOP (LE suffix)
DESCRIPTION
The A1332 is a 360° contactless high resolution programmable
magnetic angle position sensor IC. It is designed for digital
systems using an I2C interface.
This system-on-chip (SoC) architecture includes a front
end based on Circular Vertical Hall (CVH) technology,
programmable microprocessor based signal processing, and
digital I2C interface. Besides providing full-turn angular
measurement, the A1332 also provides scaling for angle
measurement applications less than 360°. It includes on-chip
EEPROM technology for flexible programming of calibration
parameters.
Digital signal processing functions, including temperature
compensation and gain/offset trim, as well as advanced output
linearization algorithms, provide an extremely accurate and
linear output for both end of shaft applications, as well as
off‑axis applications.
The A1332 is ideal for automotive applications requiring high
speed 360° angle measurements, such as: electronic power
steering (EPS), transmission, torsion bar, and other systems
that require accurate measurement of angles. The A1332
linearization schemes were designed with challenging off-axis
applications in mind.
Not to scale
The device is offered in a 14-pin TSSOP (LE) package, which
has a single die. The package is lead (Pb) free, with 100%
matte tin leadframe plating.
V+
VCC (also
programming)
BYP
To all internal circuits
Analog Front End
SOC Die
Regulator
Multisegment
CVH Element
TEST
CBYP(VCC)
Digital Subsystem
Diagnostics
SDA
CBYP(BYP)
SCL
SA0
I2 C
Interface
32-bit
Microprocessor
SA1
ADC
DGND
AGND
EEPROM
VCC
(Programming)
Functional Block Diagram
A1332-DS, Rev. 7
MCO-0000464
February 13, 2020
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
Selection Guide
Part Number
Application
A1332ELETR-T
I2C digital output
A1332KLETR-T
I2C digital output
*Contact Allegro™
Packing*
Operating Ambient Temperature, TA
4000 pieces per 13-in. reel
–40°C to 85°C
4000 pieces per 13-in. reel
–40°C to 125°C
Package
Single die,
14-pin TSSOP
Single die,
14-pin TSSOP
for additional packing options
Specifications
Absolute Maximum Ratings
Thermal Characteristics
Pin-out Diagram and Terminal List
Operating Characteristics Table
Functional Description
Overview
Operation
Diagnostic Features
Programming Modes
Application Information
Table of Contents
3
3
3
3
4
6
6
6
8
8
10
Serial Interface Description
Magnetic Target Requirements
On-Axis Applications
Off-Axis Applications
Effect of Orientation on Signal
Linearization
Correction for Eccentric Orientation
Harmonic Coefficients
PCB Layout
Typical Characteristics
Package Outline Drawing
10
11
11
11
12
13
14
15
15
16
19
Refer to the Programming Reference addendum for information on programming the device.
Allegro MicroSystems
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
2
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
SPECIFICATIONS
Absolute Maximum Ratings
Characteristic
Symbol
Notes
Rating
Unit
Forward Supply Voltage
VCC
24
V
Reverse Supply Voltage
VRCC
–18
V
Logic Input Voltage for I2C Pins
VIN
–0.5 to 5.5
V
For A1332ELETR-T, E temperature range
–40 to 85
ºC
For A1332KLETR-T, K temperature range
Operating Ambient Temperature
TA
–40 to 125
ºC
Maximum Junction Temperature
TJ(max)
165
ºC
Tstg
–65 to 170
ºC
Value
Unit
82
ºC/W
Storage Temperature
Thermal Characteristics may require derating at maximum conditions, see application information
Characteristic
Package Thermal Resistance
Symbol
Test Conditions*
RθJA
On 4-layer PCB based on JEDEC standard
*Additional thermal information available on the Allegro website
DGND 1
14 DGND
BYP 2
13 SA0
DGND 3
12 SA1
AGND 4
11 SCL
VCC 5
10 SDA
VCC 6
9 DGND
AGND 7
8 TEST
Package LE, 14-Pin
TSSOP Pin-out Diagram
Terminal List Table
PinName
Pin Number
AGND
4, 7
BYP
2
DGND
1, 3, 9,
14
SA0
13
Digital input: Sets slave address bit 0 (LSB)*; tie to BYP for 1, tie to DGND for 0
SA1
12
Digital input: Sets slave address bit 0 (LSB)*; tie to BYP for 1, tie to DGND for 0
SCL
11
Digital input: Serial clock; open drain, pull up externally to 3.3 V
SDA
10
Digital control output: digital output of evaluated target angle, also programming data
input
I2C data terminal; open drain, pull up externally to 3.3 V
TEST
8
VCC
5, 6
Function
Device analog ground terminal
Internal bypass node, connect with bypass capacitor to DGND
Device digital ground terminal
Test terminal, must be tied to DGND for correct operation
Device power supply; also input for EEPROM writing pulse
*For additional information, refer to the Programming Reference addendum, EEPROM Description
and Programming section, regarding the INTF register, I2CM field.
Allegro MicroSystems
955 Perimeter Road
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www.allegromicro.com
3
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
OPERATING CHARACTERISTICS: valid throughout full operating voltage and ambient temperature ranges, unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit2
Electrical Characteristics
Supply Voltage
VCC
4.5
5
5.5
V
Supply Current
ICC
–
16
20
mA
VCCLOW(TH)
4.4
4.55
4.75
V
VCC Low Flag Threshold3
Supply Zener Clamp
Voltage6
VZSUP
IZCC = ICC + 3 mA, TA = 25°C
26.5
–
–
V
VRCC
IRCC = –3 mA, TA = 25°C
–
–
–18
V
TA = 25°C
2
–
40
ms
tBUF
1.3
–
–
µs
Hold Time Start Condition4
tHD(STA)
0.6
–
–
µs
Setup Time for Repeated Start
Condition4
tSU(STA)
0.6
–
–
µs
SCL Low Time4
tLOW
1.3
–
–
µs
SCL High Time4
tHIGH
0.6
–
–
µs
Reverse Battery Voltage
Power-On Time4,5
tPO
I2C Interface Specification (VPU = 3.3 V on SDA and SCL pins)
Bus Free Time Between Stop
and Start4
Data Setup
Time4
Data Hold Time4
Setup Time for Stop
Condition4
tSU(DAT)
100
–
–
ns
tHD(DAT)
0
–
900
ns
tSU(STO)
0.6
–
–
µs
Logic Input Low Level (SDA and
SCL pins)6
VIL(I2C)
TA = 25ºC
–
–
0.9
V
Logic Input High Level (SDA and
SCL pins)6
VIH(I2C)
TA = 25ºC
2.1
–
3.63
V
VIN = 0 V to VCC, TA = 25ºC
–1
–
1
µA
RPU = 1 kΩ, CB = 100 pF, TA = 25ºC
–
–
0.6
V
Logic Input Current6
Output Voltage (SDA pin)6
IIN
VOL(I2C)
Logic Input Rise Time (SDA and
SCL pins)4
tr(IN)
–
–
300
ns
Logic Input Fall time (SDA and
SCL pins)4
tf(IN)
–
–
300
ns
ns
SDA Output Rise Time4
tr(OUT)
RPU = 1 kΩ, CB = 100 pF
–
–
300
SDA Output Fall Time4
tF(OUT)
RPU = 1 kΩ, CB = 100 pF
–
–
300
ns
SCL Clock Frequency 6
fCLK
TA = 25ºC
–
–
400
kHz
–
1
–
kΩ
–
–
100
pF
2.97
3.3
3.63
V
SDA and SCL Bus Pull-Up Resistor
RPU
Total Capacitive Load for Each of SDA
and SCL buses 6
CB
TA = 25ºC
Pull-Up Voltage
VPU
RPU = 1 kΩ, CB = 100 pF
1Typical
data is at TA = 25°C and VCC = 5 V and it is for design information only.
G (gauss) = 0.1 mT (millitesla).
3VCC Low Threshold Flag will be sent via the I2C interface as part of the angle measurement. When V
CC goes below the minimum value of VCCLOW(TH) . the VCC Low Flag is
set. See programming manual for details.
4Min. and Max. parameters for this characteristic are determined by design. They are not measured at final test.
5End user can customize what power-on tests are conducted at each power-on that causes a wide range of power-on times. For more information, see the description of the
CFG register, which is available in the programming manual.
6This Parameter is tested at wafer probe only.
21
Continued on the next page…
Allegro MicroSystems
955 Perimeter Road
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4
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
OPERATING CHARACTERISTICS (continued): valid throughout full operating voltage and ambient temperature ranges,
unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit2
300
–
1000
G
Magnetic Characteristics
Magnetic Field9
B
Range of input field
Angle Characteristics
Output10
Effective
–
12
–
bits
B = 300 G, TA = 25ºC, ORATE = 0
–
10.1
–
bits
ORATE = 0
–
32
–
µs
All linearization and computations disabled, see figure 1,
note 12
–
68
–
µs
For A1332ELETR-T, TA = 25 to 85°C, ideal magnet
alignment, B = 300 G, target rpm = 0, no linearization
–2
–
2
deg.
For A1332KLETR-T, TA = 25 to 125°C, ideal magnet
alignment, B = 300 G, target rpm = 0, no linearization
–2
–
2
deg.
For A1332ELETR-T, TA = 25°C, 30 samples, B = 300 G,
no internal filtering.
–
0.6
–
deg.
For A1332ELETR-T, TA = 85°C, 30 samples, B = 300 G,
no internal filtering
–
0.8
–
deg.
For A1332KLETR-T, TA = 25°C, 30 samples, B = 300 G,
no internal filtering.
–
0.6
–
deg.
For A1332KLETR-T, TA = 125°C, 30 samples, B = 300 G,
no internal filtering
–
0.8
–
deg.
For A1332ELETR-T, TA = –40°C, B = 300 G, drift
measured relative to TA = 25°C
–2
–
2
deg.
For A1332ELETR-T, TA = 85°C, B = 300 G, drift
measured relative to TA = 25°C
–1.5
–
1.5
deg.
For A1332KLETR-T, TA = –40°C, B = 300 G, drift
measured relative to TA = 25°C
–2
–
2
deg.
For A1332KLETR-T, TA = 125°C, B = 300 G, drift
measured relative to TA = 25°C
–1.5
–
1.5
deg.
–
±1
–
deg.
RESANGLE
resolution11
Angle Refresh Rate12
tANG
Response Time13
tRESPONSE
Angle Error
Angle Noise14,15
NANG3Σ
Temperature Drift
ANGLEDRIFT
ANGLEDRIFT- B = 300G, drift observed after AEC-Q100 qualification
Angle Drift over Life-Time16
LIFE
testing
7Typical
data is at TA = 25°C and VCC = 5 V and it is for design information only.
G (gauss) = 0.1 mT (millitesla).
9This represents a typical input range.
10RES
ANGLE represents the number of bits of data available for reading from the device
registers.
11Effective Resolution is calculated using the formula below:
81
(
log2 (360) - log2 3 X
32
l=1
)
l
Angle
(Degrees)
Applied Magnetic Field
50
Transducer Output
where σ is the Standard Deviation based on thirty measurements taken at each of the
0
32 angular positions, I = 11.25, 22.5, … 360.
t
12The rate at which a new angle reading is ready. This value varies with the ORATE
Response Time, tRESPONSE
selection.
13This value assumes no linearization, (harmonic, or segmented) , no IIR or ORATE
Figure 1: Definition of Response Time
filtering, and no short-stroke features enabled. This number also does not account for the
added latency associated with the I2C interface sampling rate. This value only represents
the time to read the magnetic position with no further computations made. Actual response time is dependent on EEPROM settings. Settings related to filter design, signal
path computations, and linearization will increase the response time.
14Error and noise values are with no further signal processing. Angle Error can be corrected with linearization algorithm, and Angle Noise can be reduced with internal filtering
and slower Angle Refresh Rate value. The parameters are characterized, but not measured at final test.
15This value represents 3-sigma or thrice the standard deviation of the measured samples.
16The Angle Error of most devices tested did not shift appreciably after AEC-Q100 qualification testing. However, the Angle Error of some devices was observed to drift by approximately 2 degrees after AEC-Q100 (grade 1) testing.
Allegro MicroSystems
955 Perimeter Road
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5
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
FUNCTIONAL DESCRIPTION
Overview
The A1332 incorporates a Hall sensor IC that measures the direction of the magnetic field vector through 360° in the x-y plane
(parallel to the branded face of the device). The A1332 computes
the angle based on the actual physical reading, as well as any
internal parameters that have been set by the user. The end user
can configure the output dynamic range, output scaling, and
filtering.
This device is an advanced, programmable internal microprocessor-driven system-on-chip (SoC). It includes a Circular Vertical
Hall (CVH) analog front end, a high speed sampling A-to-D converter, digital filtering, a 32-bit custom microprocessor, a digital
control I2C interface, and digital output of processed angle data.
Advanced linearization, offset, and gain adjustment options
are available in the A1332. These options can be configured in
onboard EEPROM providing a wide range of sensing solutions
in the same device. Device performance can be optimized by
enabling individual functions or disabling them in EEPROM to
minimize latency.
Operation
The device is designed to acquire angular position data by sampling a rotating bipolar magnetic target using a multi-segmented
circular vertical Hall effect (CVH) detector. The analog output
is processed, and then digitized, and compensated before being
loaded into the output register. Refer to figure 2 for a depiction of
the signal process flow described here.
• Analog Front End In this stage, the applied magnetic signal is
detected and digitized for more advanced processing.
A1 CVH Element. The CVH is the actual magnetic sensing element that measures the direction of the applied magnetic vector.
A2 Analog Signal Conditioning. The signal acquired by the
CVH is sampled.
A3 A to D Converter. The analog signal is digitized and handed
off to the Digital Front End stage.
• Digital Front End In this preprocessing stage, the digitized
signal is conditioned for analysis.
D1 Digital Signal Conditioning. The digitized signal is decimated and band pass filtered.
D2 Raw Angle Computation. For each sample, the raw angle
value is calculated.
• Microprocessor The preprocess signal is subjected to various
standard and user-selected computations. The type and selection
of computations used involves a trade-off between precision and
increased response time in producing the final output.
P1 Angle Averaging. The raw angle data is received in a periodic stream (every 32 µs), and several samples are accumulated
and averaged, based on user selected output rate. This feature
increases the effective resolution of the system. The amount of
averaging is determined by the user-programmable ORATE (output rate) field. The user can configure the quantity of averaged
samples by powers of two to determine the refresh rate, the rate
at which successive averaged angle values are fed into the post
processing stages. The available rates are set as follows:
ORATE
[2:0]
Quantity of Samples
Averaged
Refresh Rate
(µs)
000
001
010
011
100
101
110
111
1
2
4
8
16
32
64
128
32
64
128
256
512
1024
2048
4096
P1a IIR Filter (Optional) The optional IIR filter can provide
more advanced multi-order filtering of the input signal. Filter
coefficients can be user-programmed, and the FI bit can be programmed by the user to enable or disable this feature.
P1b Angle Compensation over Temperature and Magnetic
Field (Optional) The A1332 is capable of compensating for drift
in angle readings that result from changes in the device temperature through the operating ambient temperature range. The device
comes from the factory pre-programmed with coefficient settings
to allow compensation of linear shifts of angle with temperature.
The TC bit can be programmed by the user to enable or disable
this feature. The default value from Allegro factory is “enabled”.
Please note, this bit must be set, to meet specifications on angle
error related items in the data-sheet.
P1c Prelinearization 0 Offset (Optional, but required if linearization used.) The expected angle values should be distributed
throughout the input dynamic range to optimize angle post-
Allegro MicroSystems
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6
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
A1
CVH
Element
A2
Analog Signal
Conditioning
A3
A to D
Converter
D1
Digital Signal
Conditioning
D2
Raw Angle
Computation
P1
Angle
Averaging
Analog
Front End
(Applied Magnetic
Signal Detection)
Digital
Front End
(Digital Logic for
Processing)
Sample Rate
(Resolution)
(Optional)
IR Filter
P1a
Angle
Compensation
P1b
P1c
(Optional)
Prelinearization
0 Offset
P1d
(Optional)
Prelinearization
Rotation
Microprocessor
(Angle Processing)
P2
Minimum/
Maximum
Angle Check*
P3
Gain Adjust*
(Optional)
Linearization
Segmented or
Harmonic
P3a
SRAM
P4 Postlinearization
0 Offset
P4a
(Optional)
Postlinearization
Rotation
EEPROM
Rounding
P5 Angle
to 12 Bits
(Optional)
P6 Angle Clamping*
(Optional)
Angle
Inversion
P6a
Primary Serial Interface
* Short Stroke Applications Only
Figure 2: Signal Processing Flow
(refer by index number to text descriptions)
Allegro MicroSystems
955 Perimeter Road
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7
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
processing. This is mostly needed for applications that utilize
full 360-degree rotations. This value establishes the position
that will correspond to zero error. This value should be set such
that the 360 → 0 degree range corresponds to the 4095 → 0
code range. Setting this point is critical if linearization is used,
whether segmented or harmonic. This is required, prior to going
through linearization, because both linearization methods require
a continuous input function to operate correctly. Set using the
LIN_OFFSET field.
P1d Prelinearization Rotation (Optional, but required if linearization used). The linearization algorithms require input functions
that are both continuous and monotonically increasing. The LR
bit sets which relative direction of target rotation results in an
increasing angle value. The bit must be set such that the input to
the linearization algorithm is increasing.
P2 Minimum/Maximum Angle Check. The device compares
the raw angle value to the angle value boundaries set by the
user programming the MIN_ANGLE_S or MAX_ANGLE_S
fields. If the angle is excessive, an error flag is set at ERR[AH]
(high boundary violation) or ERR[AL] (low boundary violation). (Note: To bypass this feature, set MIN_ANGLE_S to 0 and
MAX_ANGLE_S to 4095.)
P3 Gain Adjust. This bit adjusts the output dynamic range of the
device. For example, if the application only requires 45 degrees
of stroke, the user can set this field (to 8 in this example) such
that a 45-degree angular change would be distributed across the
entire 4095 → 0 code range. Set using the GAIN field.
P3a Linearization (Optional). Applies user-programmed error
correction coefficients (set in the LINC registers) to the raw angle
measurements. Use the HL bit to enable harmonic linearization
and the SL bit to enable segmented linearization (along with the
LIN_SEL field to select the type of segmented linearization).
P4 Postlinearization 0 Offset. This computation assigns the final
angle offset value, to set the low expected angle value to code 0
in the output dynamic range, after all linearization and processing
has been completed. Set using the ZERO_OFFSET field.
P4a Postlinearization Rotation (Optional). This feature allows
the user to chose the polarity of the final angle output, relative to
the result of the Prelinearization Rotation direction setting (LR
bit, described above). Set using the RO bit.
P5 Angle Rounding to 12 Bits. All of the internal calculations
for angle processing in the A1332 take place with 16-bit precision. This step truncates the data into a 12 bit word for output
through the Primary Serial Interface.
P6 Angle Clamping. The A1332 has the ability to apply digital clamps to the output signal. This feature is most useful for
applications that use angle strokes less than 360 degrees. If the
output signal exceeds the upper clamp, the output will stay at
the clamped value. If the output signal is lower than the lower
clamp, the output will stay at the low clamp value. Set using
the CLAMP_HI] and CLAMP_LO fields. (Note: To bypass this
feature, set CLAMP_HI to 4095 and CLAMP_LO to 0.)
P6a Angle Inversion (Optional). This calculation subtracts the
angle from the high clamp.
Diagnostic Features
The A1332 features several diagnostic features and status flags
to let the user know if any issues are present with the A1332 or
associated magnetic system:
Condition
Diagnostic Response
VCC < VCCLOW(TH)(min)
UV error flag is set
VCC > 8.8 V
OV error flag is set
Field > MAG_HIGH
MH flag is set
Field < MAG_LOW
ML flag is set
Angle processing errors
AT flag is set
Angle out of range
AHF, ALF flags are set
System status
ALIVE always counting indicating
angles being processed
The SDA pin state changes according to the state of the VCC
ramp, as shown in Figure 3.
For more information on diagnostic features and flags, please
refer to the programmers guide for a more complete description
of the available flags and settings.
Allegro MicroSystems
955 Perimeter Road
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8
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
Programming Modes
The EEPROM can be written through the primary serial interface
to enter process coefficients and select options. Certain operating
commands also are available by writing directly to SRAM. The
EEPROM and SRAM provide parallel data structures for operating parameters. The SRAM provides a rapid test and measurement environment for application development and bench testing.
The EEPROM provides persistent storage at end of line for final
parameters. At initialization, the EEPROM contents are read into
the corresponding SRAM. The SRAM can be overwritten during
operation (although it is not recommended). the EEPROM is
permanently locked by setting the lock EEPROM [LE] bit in the
EEPROM.
The A1332 is programmed through the primary serial interface,
an I2C interface receiving pulses through the SDA and SCL pins,
with additional power provided by pulses on the VCC pin to set
the EEPROM bit fields.
VCC (V)
4.4
3.8
3.7
VCC Low Flag Threshold, VCCLOW(TH)
POR
Angle
output
accuracy
reduced
SDA Pin
State
High
Impedance
Error
Flag Set
Angle
output
accuracy
reduced
Accurate
Angle Output
Error
Flag Set
POR
High
Impedance
t
Figure 3: Relationship of VCC and SDA output
Allegro MicroSystems
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9
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
APPLICATION INFORMATION
Serial Interface Description
The A1332 features an I2C compliant interface for communication with a host microcontroller, or Master. A basic circuit for
configuring the A1332 package is shown in Figure 4. It is recommended that both the SCL and SDA lines be tied to 3.3 V via a
1 kΩ pull-up resistor. If using a Pull-Up voltage of 5 V, it is
recommended to limit current by using a higher value pull-up
resistance that 1 K.
If the SDA pin is tied to 5 V, instead of 3.3 V, this results in the
forward biasing of an internal diode in the A1332 which could
conduct current into the digital voltage regulator internal to the
device. This may result in degraded voltage regulation performance. Current- limiting resistors have been implemented
on-chip to limit this effect. Measurements show that exposure to
this condition does not damage the IC in any permanent manner.
However, for best results, it is recommended that the Serial Logic
pins SDA and SCL be tied to 3.3 V and not 5 V VCC.
SDA Pull-Up = 3.3 V
SDA Pull-Up = 5 V
3.3 V Internal Regulator
3.3 V Internal Regulator
3.3 V External Supply
5 V External Supply
Digital Sub-System
Internal
Resistor
+
-
+
-
+
-
+
Internal
Diode:
OFF
Internal
Diode:
ON
Pull-Up
Resistor
SDA
Pin
Digital Sub-System
Internal
Resistor
Pull-Up
Resistor
SDA
Pin
Current Flows from VCC into
3.3 V Internal Regulator.
Regulator may suffer some
degradation in performance.
Figure 4: SDA Pin Schematic
A1332 will continue to function
with the 5 V SDA Pull-Up, but
this is not a desirable coniguration.
Allegro MicroSystems
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10
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
Magnetic Target Requirements
There are two main sensing configurations for magnetic angle
sensing, on axis and off axis. On-axis (end of shaft) refers to
when the center axis of a magnet lines up with the center of the
sensing element. Off-axis (side shaft) refers to when the angle
sensor is mounted along the edge of a magnet. Figure 9 illustrates
on and off axis sensing configurations.
Table 1: Target Magnet Parameters
Magnetic Material
Neodymium (bonded)
15
4
10
4
Neodymium (sintered)
8
3
Neodymium / SmCo
6
2.5
There are two major challenges with off axis angle sensing
applications. The first is field strength. All efforts should be
conducted to maximize magnetic signal strength as seen by the
device. The goal is a minimum of 300 G. Field strength can be
maximized by using high quality magnetic material, and by minimizing the distance between the sensor and the magnet. Another
challenge is overcoming the inherent non-linearity of the magnetic field vector generated at the edge of a magnet. The device
has two linearization algorithms that can compensate for much of
the geometric error. Harmonic linearization is recommended for
off-axis applications.
VCC = 5 V
0.1 µF
3.3 V
Diameter
*A sintered Neodymium magnet with 10 mm (or greater) diameter and 4 mm thickness is the recommended magnet for redundant applications.
14
13
12
11
10
9
8
7
6
5
4
2
1
VCC VCC
SA1
BYP
A1332
SCL
SDA
TEST
AGND
AGND
AGND
DGND
DGND
DGND
Host/Master
Microprocessor
1 kΩ
S
N
3
SA0
1 kΩ
Thickness
Angle Error (±°)
OFF-AXIS APPLICATIONS
Thickness
(mm)
Neodymium (sintered)*
ON-AXIS APPLICATIONS
Some common on-axis applications for the device include digital
potentiometer, motor sensing, power steering, and throttle sensing. The A1332 is designed to operate with magnets constructed
with a variety of magnetic materials, cylindrical geometries, and
field strengths, as shown in Table 1. The device has two internal
linearization algorithms that can compensate for much of the
error due to alignment. Contact Allegro for more detailed information on magnet selection and theoretical error.
Diameter
(mm)
0.1 µF
0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Eccentricity of SOC Chip Relative to Magnet Rotation Axis (mm)
Figure 6: Simulated Error versus Eccentricity for a
10 mm x 4 mm Neodymium Magnet at a 2.7 mm Air
Gap.
Typical Systemic Error versus magnet to sensor eccentricity (daxial),
Note: “Systemic Error” refers to application errors in alignment and
system timing. It does not refer to sensor IC device errors. The data
in this graph is simulated with ideal magnetization.
Figure 5: Typical A1332 Configuration
A1332 set up for serial address 0xC
Allegro MicroSystems
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11
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
Effect of Orientation on Signal
+|B|
0G
360°
+|B|
Detected
Rotation
Magnetic
Flux
0G
Zero
Crossing
Figure 7: Magnetic Field Flux Lines
The magnetic field flux lines run fixed field lines coming out of
the north pole and going into the south pole of the magnet. The
peak flux densities are between the poles.
90°
180°
0°
360°
270°
Figure 8: Hall Element Detects Rotating Relative Polarity
of Magnetic Field
As the magnet rotates, the Hall element detects the rotating relative
polarity of the magnetic field (solid line); when the center of rotation is
centered on the Hall element, the magnetic flux amplitude is constant
(dashed line).
daxial(on-axis)
daxial(off-axis)
AG (off axis)
Axis of
Rotation
AG (on axis)
AG (on axis, centered)
Magnetic
Flux Lines
Hall element
Figure 9: Centering the Axis of Magnet Rotation on
the Hall Element
Centering the axis of magnet rotation on the Hall element provides the strongest signal in all degrees of rotation.
Figure 10: Rapid Degeneration of Magnetic Flux Density
The magnetic flux density degenerates rapidly away from the plane of
peak north-south polarity. When the axis of rotation is placed away from
the Hall element, the device must be placed closer to the magnetic poles
to maintain an adequate level of flux at the Hall element.
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12
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
Linearization
Magnetic fields are generally not completely linear throughout
the full range of target positions. This can be the result of nonuniformities in mechanical motion or of material composition.
In some applications, it may be required to apply a mathematical
transfer function to the angle that is reported by the A1332.
The A1332 has built-in functions for performing linearization on
the acquired angle data. It is capable of performing one of two
different linearization methods: harmonic linearization and piecewise (segmented) linearization.
Segmented linearization breaks up the output dynamic range
into 16 equal segments. Each segment is then represented by the
equation of a straight line between the two endpoints of the segment. Using this basic principle, it is possible to tailor the output
response to compensate for mechanical non-linearity.
One example is a fluid level detector in a vehicle fuel tank.
Because of requirements to conform the tank and to provide
stiffening, fuel tanks often do not have a uniform shape. A level
detector with a linear sensor in this application would not correctly indicate the remaining volume of fuel in the tank without
some mathematical conversion. Figure 11 graphically illustrates
the general concept.
Harmonic linearization utilizes the Fourier series in order to
compensate for periodic error components. In the most basic of
terms, the Fourier series is used to represent a periodic signal
Meter and
Sender
using a sum of ideal periodic waveforms. The A1332 is capable
of utilizing up to 15 Fourier series components to linearize the
output transfer function.
While it can be used for many applications, harmonic linearization is most useful for 360-degree applications. The error curve
for a rotating magnet that is not perfectly aligned will most often
have an error waveform that is periodic. This is phenomenon is
especially true for systems where the sensor is mounted off-axis
relative to the magnet. Figure 12 illustrates this periodic error.
An initial set of linearization coefficients is created by characterizing the application experimentally. With all signal processing
options configured, the device is used to sense the applied magnetic field, B: at a target zero-degrees of rotation reference angle
and at regular intervals. For segmented linearization, 16 samples
are taken: at nominal zero degrees and every 1/16 interval (22.5°)
of the full 360° rotational input range. Each angle is read from
the ANG[ANGLE] register and recorded.
These values are loaded into the Allegro ASEK programming
utility for the device, or an equivalent customer software program, and to generate coefficients corresponding to the values.
The user then uses the software load function to transmit the
coefficients to the EEPROM. Each of the coefficient values can
be individually overwritten during normal operation by writing
directly to the corresponding SRAM.
Fill pipe
Linear Depth
Linearized rate
Uniform walls
Angled walls
Wall stiffener cavities
Angled walls, uneven bottom
Fuel Volume
0
Figure 11: Varying Volumes in an Integrated Vehicle Fuel Tank
An integrated vehicle fuel tank has varying volumes according to depth due to structural elements. As shown in the chart, this results in a
variable rate of fuel level change, depending on volume at the given depth, and a linearized transfer function can be used against the integral
volume.
Allegro MicroSystems
955 Perimeter Road
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13
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
Correction for Eccentric Orientation
∆daxial
∆daxial =
+ phase,
+ amplitude
∆daxial
∆daxial
∆daxial =
+ phase,
+ + amplitude
∆daxial
∆daxial =
+ phase,
– amplitude
∆daxial =
+ phase,
– – amplitude
360
rs
Ta
r
io
n
ge
t
Fu
nc
tio
n
180
n
io
ag
ne
tic
In
Li
pu
t
ne
ar
iz
at
In
With the axis of rotation
aligned with the Hall
element, linearization
coefficients are a simple
inversion of the input.
ve
Figure 12a: Linearization Coefficients
Detected Angle (°)
270
M
90
0
Systematic eccentricity can
be factored out by appropriate linearization coefficients.
For off-axis applications,
the harmonic linearization
method is recommended.
0
Error Correction (V)
Figure 12b: Any Eccentricity is Evaluated as
an Error.
90
180
Target Rotational Position (°)
270
360
+V
∆daxial Correction
Corrected Angle Output
Inversion Result
0
0
90
180
Device Output Position (°)
270
360
Allegro MicroSystems
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14
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
HARMONIC COEFFICIENTS
PCB Layout
The device supports up to 15 harmonics. Each harmonic is characterized by an amplitude and a phase coefficient.
Bypass and decoupling capacitor should be placed as close as
possible to corresponding pins, with low impedance traces.
Capacitors should be tied to a low impedance ground plane whenever possible.
To apply harmonic linearization, the device:
1. Calculates the error factors.
2. Applies any programmed offsets.
3. Calculates the linearization factor as:
An × sin(n × t + φn )
4095
fun
ctio
O
n
ut
pu
tf
un
ct
io
n
Interpolated Linear Position
(y-axis values represent
16 equal intervals)
ut
Inp
A
Maximum Full Scale Input
on
cti
n
t fu
A
–xLIN_3
u
Inp
–640
A Coefficients stored in
BIN10
BIN3
BIN2
0
BIN16
2432
n
ct
io
un
tf
ut
pu
xLIN_10
O
BIN1
BIN0 Minimum Full Scale Input
Magnetic Input Values
(15 x-axis values read
and used to calculate
coefficients)
EEPROM
Figure 13: Sample of Linearization Function Transfer Characteristic.
Allegro MicroSystems
955 Perimeter Road
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15
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
TYPICAL CHARACTERISTICS
1
0.8
Angle Error (Degrees)
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0
50
100
150
250
200
Encoder Position (Degrees)
300
350
Figure 14: Angle Error versus Encoder Position
1
2.0
1.8
Mean
Mean
±3 Sigma
±3 Sigma
1.5
1.4
Drift (Degrees)
Angle Error (Degrees)
1.6
1.2
1.0
0.8
1.0
0.6
0.5
0.4
0.2
-1
-40
-20
0
20
40
60
Temperature (ºC)
80
100
Figure 15: Peak Angle Error over Temperature
120
-1
0
50
Temperature (ºC)
100
Figure 16: Maximum Absolute Drift from 25ºC
Measurement
Allegro MicroSystems
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16
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
1
16
125ºC
25ºC
–40ºC
14
Mean
+3 Sigma
-3 Sigma
0.8
A1332 NOISE in Degrees
Frequency (%)
12
10
8
6
4
0.6
0.4
0.2
2
0
0
0.4
0.2
0
-50
1
0.8
0.6
Noise in Degrees
0
50
100
150
Ambient Temperature (ºC)
Figure 17: Noise Distribution vs. Temperature
(1 σ, 300 G, VCC = 4.5 V)
Figure 18: Noise Distribution vs. Temperature
(1 σ, 300 G, VCC = 4.5 V)
20
12
125ºC
25ºC
–40ºC
10
19
18
17
A1332 ICC in mA
Frequency (%)
8
6
4
16
15
14
Mean
2
13
+3 Sigma
-3 Sigma
0
12
14
16
18
ICC in mA
Figure 19: ICC Distribution vs. Temperature
(VCC = 5.5 V)
20
12
-50
0
50
100
Ambient Temperature in Degrees C
150
Figure 20: ICC vs. Temperature
(VCC = 5.5 V)
Allegro MicroSystems
955 Perimeter Road
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17
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
PACKAGE OUTLINE DRAWING
For Reference Only – Not for Tooling Use
(Reference MO-153 AB-1)
NOT TO SCALE
Dimensions in millimeters
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
5.00 ±0.10
1.45
0.45
8º
0º
D
14
0.65
14
0.20
0.09
1.70
E
D
4.40 ±0.10
6.00
6.40 BSC
0.60
A
+0.15
–0.10
1.00 REF
1
2
16X
0.10
1.10 MAX
C
0.30
0.19
1
0.25 BSC
Branded Face
C
SEATING
PLANE
B
SEATING PLANE
GAUGE PLANE
2
PCB Layout Reference View
0.15
0.00
0.65 BSC
A
Terminal #1 mark area
B
Reference land pattern layout (reference IPC7351 TSOP65P640X120-14M);
All pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary
to meet application process requirements and PCB layout tolerances; when
mounting on a multilayer PCB, thermal vias at the exposed thermal pad land
can improve thermal dissipation (reference EIA/JEDEC Standard JESD51-5)
C
Branding scale and appearance at supplier discretion
D
Hall element, not to scale
E
Active Area Depth = 0.36 mm (Ref)
NNNNNNNNNNNN
YYWW
LLLLLLLLLLLL
1
C
Standard Branding Reference View
N = Device part number
= Supplier emblem
Y = Last two digits of year of manufacture
W = Week of manufacture
L = Lot number
Figure 21: Package LE, 14-Pin TSSOP (Single Die Version)
Allegro MicroSystems
955 Perimeter Road
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18
A1332
Precision Hall-Effect Angle Sensor IC with I2C Interface
Revision History
Number
Date
Description
–
September 11, 2014
1
January 21, 2015
Added K Variant and Typical Characteristic Graphs
Initial release
2
January 23, 2015
Revised Noise Distribution plots
3
December 1, 2015
Status of product changed to “Not for New Design”
4
December 17, 2015
5
July 2, 2018
Corrected CVH location in single-die package outline drawing
Product status changed to Last-Time Buy
6
February 4, 2019
Product status changed to Discontinued
7
February 13, 2020
Minor editorial updates
I2C™ is a trademark of Philips Semiconductors.
Copyright 2020, Allegro MicroSystems.
Allegro MicroSystems reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit
improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the
information being relied upon is current.
Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of
Allegro’s product can reasonably be expected to cause bodily harm.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems assumes no responsibility for its use; nor
for any infringement of patents or other rights of third parties which may result from its use.
Copies of this document are considered uncontrolled documents.
For the latest version of this document, visit our website:
www.allegromicro.com
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