A1335 Datasheet

A1335
Precision Hall-Effect Angle Sensor IC
with I 2C, SPI, and SENT Interfaces
FEATURES AND BENEFITS
• 360° contactless high-resolution angle position sensor
• CVH (Circular Vertical Hall) technology
• Available with either a single die or dual independent die
housed within a single package
• Digital output format selectable among SPI, I2C, and
SENT (Single-Edge Nibble Transmission)
• SENT output is SAEJ2716 JAN2010 compliant, with
Allegro proprietary enhanced programmable features
• Customer-programmable SENT tick times, ranging
from 0.5 to 7.9 µs
• SPI interface allows use of multiple independent sensor
ICs for applications requiring redundancy
• Refresh rate: 32 µs, 12-bit resolution
• Wide range of diagnostics enable automotive applications
to achieve ASIL-D compliance
• Programmable via Manchester encoding on the VCC
line, reducing external wiring
• Automotive temperature range: –40°C to 150°C
• AEC-Q100 automotive qualified
• Two types of linearization algorithms offered: harmonic
linearization and segmented linearization
□□ Enables off-axis operation
Continued on the next page…
Packages:
The A1335 is a 360° contactless high-resolution programmable
magnetic angle position sensor IC. It is designed for digital
systems and is capable of communicating via an I2C, SPI, or
SENT interface.
This system-on-chip (SoC) architecture includes a front
end based on Circular Vertical Hall (CVH) technology,
programmable microprocessor-based signal processing, and
features an interface capable of supporting I2C, SPI, and SENT.
Besides providing full-turn angular measurement, the A1335
also provides scaling for angle measurement applications less
than 360°. It includes on-chip EEPROM technology, capable of
supporting up to 100 read/write cycles, 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 A1335 is ideal for automotive applications requiring highspeed 360° angle measurements, such as: electronic power
steering (EPS), transmission, torsion bar, and other systems
that require accurate measurement of angles. The A1335
linearization schemes were designed with challenging off-axis
applications in mind.
The A1335 is available as a single die in a 14-pin TSSOP, or
dual die in a 24-pin TSSOP. Both packages are lead (Pb) free
with 100% matte-tin leadframe plating.
Not to scale
Single SoC, 14-pin TSSOP
(suffix LE)
DESCRIPTION
Dual Independent SoCs, 24-pin
TSSOP (suffix LE)
V+
VCC (also
programming)
BYP
To all internal circuits
Analog Front End
SOC Die
Regulator
Multisegment
CVH Element
SENT
CBYP(VCC)
SENT
Interface
Diagnostics
Digital
Subsystem
SDA/MISO
SCL/SCLK
CBYP(BYP)
SA0/CS
I2C/SPI
Interface
32-bit
Microprocessor
SA1/MOSI
ISEL
DGND
VCC
(Programming)
EEPROM
AGND
Functional Block Diagram
A1335-DS
ADC
Industry-leading linearization
enables off-axis (side-shaft)
operation
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
Features and Benefits (continued)
• Programmable range—can scale 22.5° to full-scale digital
output
• Microprocessor-based output linearization
• EEPROM with Error Correction Control (ECC) for trimming
calibration
Selection Guide
Part Number
A1335LLETR-T
A1335LLETR-DD-T
System Die
Single
Dual
Package
14-pin TSSOP
24-pin TSSOP
• 1 mm thin (TSSOP) package
• Improved air-gap performance, based on continuous
background calibration
Packing*
4000 pieces per 13-in. reel
4000 pieces per 13-in. reel
*Contact Allegro for additional packing options
Table of Contents
Specifications
3
Functional Description
8
Absolute Maximum Ratings
Thermal Characteristics
Pinout Diagram and Terminal List
Operating Characteristics
Overview
Operation
Diagnostic Features
Programming Modes
Manchester Serial Interface
Entering Manchester Communication Mode
Transaction Types
Writing to EEPROM
Manchester Interface Reference
SENT Output Mode
SENT Message Structure
3
3
4
5
8
8
11
12
13
13
13
13
14
15
16
Application Information
17
Typical Performance Characteristics
Package Outline Drawings
25
27
Serial Interface Description
Magnetic Target Requirements
Field Strength
On-Axis Applications
Off-Axis Applications
Effect of Orientation on Signal
Linearization
Correction for Eccentric Orientation
Harmonic Coefficients
PCB Layout
17
18
18
19
19
21
22
23
24
24
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
SPECIFICATIONS
Absolute Maximum Ratings
Characteristic
Symbol
Notes
Rating
Unit
Forward Supply Voltage
VCC
24
V
Reverse Supply Voltage
VRCC
–18
V
All Other Pins
VIN
Operating Ambient Temperature
TA
Maximum Junction Temperature
Storage Temperature
–0.5 to 5.5
V
–40 to 150
ºC
TJ(max)
165
ºC
Tstg
–65 to 170
ºC
L temperature range
THERMAL CHARACTERISTICS: May require derating at maximum conditions; see application information
Characteristic
Package Thermal Resistance
Symbol
RθJA
Test Conditions*
Value
Unit
LE-14 package
82
ºC/W
LE-24 package
117
ºC/W
*Additional thermal information available on the Allegro website.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
Terminal List Table
Pin Name1
Pin Number
LE-14
LE-24
VCC_1
5
5
12 SA1/MOSI
VCC_2
–
17
NC 4
11 SCL/SCLK
AGND_1
7
3
VCC 5
10 SDA/MISO
AGND_2
–
15
BYP_1
2
2
Internal bypass node, connect with bypass capacitor to DGND (die 1).
Internal bypass node, connect with bypass capacitor to DGND (die 2).
DGND 1
BYP 2
DGND 3
NC 6
AGND 7
14 DGND
13 SA0/CS
9 SENT
8 ISEL
LE-14 Package
(Single SoC)
DGND_1 1
BYP_1 2
24 DGND_1
23 SA0_1/CS_1
AGND_1 3
22 SA1_1/MOSI_1
NC 4
21 SCL_1/SCLK_1
VCC_1 5
20 SDA_1/MISO_1
ISEL_2 6
19 SENT_1
SENT_2 7
18 ISEL_1
SDA_2/MISO_2 8
17 VCC_2
SCL_2/SCLK_2 9
16 NC
SA1_2/MOSI_2 10
15 AGND_2
SA0_2/CS_2 11
DGND_2 12
14 BYP_2
13 DGND_2
LE-24 Package
(Dual SoC)
Function
Device power supply and input for EEPROM writing pulses. Used
to enter/exit Manchester Serial Communication mode; serves as
programming data input once mode has been entered.
Device analog ground terminal.
BYP_2
–
14
DGND_1
1, 3, 14
1, 24
DGND_2
–
12,13
ISEL_1
8
18
Selects between I2C operation (set to logic low)
or SPI operation (set to logic high) (for SENT/Manchester operation set
low) (die 1)
ISEL_2
–
6
Selects between I2C operation (set to logic low)
or SPI operation (set to logic high) (for SENT/Manchester operation set
low) (die 2).
NC
4, 6
4, 16
SA0_1/
C̄ S̄¯ _1
SA0_2/
C̄ S̄¯ _2
SA1_1/
MOSI_1
13
–
12
Device digital ground terminal.
Not Connected; connect to GND for optimal ESD performance.
23
I2C: SA0 digital input. Sets slave address bit 0 (LSB)2; tie to BYP for 1,
tie to DGND for 0.
SPI: Chip Select input, active low (die 1).
Manchester: LSB of the ID value for Die 1. tie to BYP for 1, to DGND
for 0. Must be in I2C operation (ISEL set to a logic low).
11
I2C: SA0 digital input. Sets slave address bit 0 (LSB)2; tie to BYP for 1,
tie to DGND for 0.
SPI: Chip Select input, active low (die 2).
Manchester: LSB of the ID value for Die 2. tie to BYP for 1, to DGND
for 0. Must be in I2C operation (ISEL set to a logic low).
22
I2C: SA1 digital input: Sets slave address bit 1 (LSB)2; tie to BYP for 1,
tie to DGND for 0.
SPI: Master Output / Slave Input terminal (die 1).
Manchester: MSB of the ID value for Die 1. tie to BYP for 1, to DGND
for 0. Must be in I2C operation (ISEL set to a logic low).
SA1_2/
MOSI_2
–
10
I2C: SA1 digital input: Sets slave address bit 1 (LSB)2; tie to BYP for 1,
tie to DGND for 0.
SPI: Master Output / Slave Input terminal (die 2).
Manchester: MSB of the ID value for Die 2. tie to BYP for 1, to DGND
for 0. Must be in I2C operation (ISEL set to a logic low).
SCL_1/
SCLK_1
11
21
Digital input: Serial clock (I2C: SCL, SPI: SCLK); open drain, pull up
externally to 3.3 V (die 1).
SCL_2/
SCLK_2
–
9
Digital input: Serial clock (I2C: SCL, SPI: SCLK); open drain, pull up
externally to 3.3 V (die 2).
SDA_1/
MISO_1
10
20
I2C: Digital data terminal: digital output of evaluated target angle, also
programming data input; open drain, pull up externally to 3.3 V (die 1).
SPI: Master Input / Slave Output terminal (die 1).
SDA_2/
MISO_2
–
8
I2C: Digital data terminal: digital output of evaluated target angle, also
programming data input; open drain, pull up externally to 3.3 V (die 2).
SPI: Master Input / Slave Output terminal (die 2).
SENT_1
9
19
SENT transmission output terminal (die 1); Manchester output in
Manchester mode; open drain, pull-up to external supply.
SENT_2
–
7
SENT transmission output terminal (die 2); Manchester output in
Manchester mode; open drain, pull-up to external supply.
1 The
number following the underscore refers to the die number in a dual SOC variant
additional information, refer to the Programming Reference addendum, EEPROM Description and Programming section, regarding the
INTF register, I2CM field.
2 For
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
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
–
15
20
mA
VCCLOW(TH)
4.4
4.55
4.75
V
VCC Low Flag Threshold
Supply Zener Clamp Voltage
VZSUP
IZCC = ICC + 3 mA, TA = 25°C
26.5
–
–
V
Reverse Battery Voltage
VRCC
IRCC = –3 mA, TA = 25°C
–
–
–18
V
tPO
TA = 25°C
2
–
40
ms
Digital Input High Voltage3
VIH
MOSI, SCLK, C̄¯ S̄¯ pins
2.8
–
3.63
V
Digital Input Low Voltage3
VIL
MOSI, SCLK, C̄¯ S̄¯ pins
–
–
0.5
V
SPI Output High Voltage
VOH
MISO pins, TA = 25°C
2.93
3.3
3.69
V
SPI Output Low Voltage
VOL
MISO pins
–
0.3
–
V
SPI Clock Frequency3
fSCLK
Power-On Time3,4
SPI Interface Specifications5
MISO pins, CL = 50 pF
0.1
–
10
MHz
Chip Select to First SCLK Edge3
tCS
Time from C̄¯ S̄¯ going low to SCLK falling edge
50
–
–
ns
Data Output Valid Time3
tDAV
Data output valid after SCLK falling edge
–
45
–
ns
MOSI Setup
Time3
tSU
Input setup time before SCLK rising edge
10
–
–
ns
tHD
Input hold time after SCLK rising edge
50
–
–
ns
tCHD
Hold SCLK high time before C̄¯ S̄¯ rising edge
5
–
–
ns
Loading on digital output (MISO) pin
–
–
50
pF
tBUF
1.3
–
–
µs
Hold Time Start Condition3
tHD(STA)
0.6
–
–
µs
Setup Time for Repeated Start
Condition3
tSU(STA)
0.6
–
–
µs
tLOW
1.3
–
–
µs
MOSI Hold Time3
SCLK to C̄¯ S̄¯ Hold
Time3
Load Capacitance3
CL
I2C Interface Specifications (VPU = 3.3 V on SDA and SCL pins)
Bus Free Time Between Stop
and Start3
SCL Low Time3
SCL High
Time3
Data Setup Time3
Data Hold
Time3
tHIGH
0.6
–
–
µs
tSU(DAT)
100
–
–
ns
tHD(DAT)
0
–
900
ns
Setup Time for Stop Condition3
tSU(STO)
0.6
–
–
µs
Logic Input Low Level (SDA and
SCL pins)13
VIL(I2C)
–
–
0.9
V
Logic Input High Level (SDA and
SCL pins)
VIH(I2C)
2.1
–
3.63
V
Continued on the next page…
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
OPERATING CHARACTERISTICS (continued): Valid throughout full operating voltage and ambient temperature ranges,
unless otherwise specified
Characteristic
I2C
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit2
VIN = 0 V to VCC
–1
–
1
µA
RPU = 1 kΩ, CB = 100 pF, TA = 25°C
–
–
0.6
V
Interface Specifications (VPU = 3.3 V on SDA and SCL pins), continued
Logic Input Current3
IIN
Output Voltage (SDA pin)
VOL(I2C)
Logic Input Rise Time (SDA and
SCL pins)3
tr(IN)
–
–
300
ns
Logic Input Fall Time (SDA and
SCL pins)3
tf(IN)
–
–
300
ns
SDA Output Rise Time3
tr(OUT)
RPU = 1 kΩ, CB = 100 pF
–
–
300
ns
SDA Output Fall Time3
tF(OUT)
RPU = 1 kΩ, CB = 100 pF
–
–
300
ns
Frequency13
SCL Clock
fCLK
–
–
400
kHz
SDA and SCL Bus Pull-Up Resistor
RPU
–
1
–
kΩ
Total Capacitive Load on
SDA Line3
Pull-Up Voltage3
SENT Interface
CB
–
–
100
pF
2.97
3.3
3.63
V
Tick time = 3 µs
–
–
1
ms
tSENTMIN
Tick time = 0.5 µs, 3 data nibbles, SCN, and
CRC, nibble length = 27 ticks
–
96
–
µs
VSENT(L)
5 kΩ ≤ Rpullup ≤ 50 kΩ
VPU
RPU = 1 kΩ, CB = 100 pF
tSENT
Specifications3
SENT Message Duration
Minimum Programmable SENT
Message Duration
SENT Output Signal
SENT Trigger Signal
Minimum Time Frame for SENT
Trigger Signal
VSENT(H)
–
–
0.10
V
Minimum Rpullup = 5 kΩ
0.9 × VS
–
–
V
Maximum Rpullup = 50 kΩ
0.7 × VS
–
–
V
VSENTtrig(L)
–
–
1.4
V
VSENTtrig(H)
2.8
–
–
V
Ttrig(MIN)
2
–
–
µs
Triggered Delay Time
tdSENT
From end of trigger pulse to beginning of SENT
message frame.
TSENT (SENT_MODE 3 and SENT_MODE 4)
–
7
–
Tick
Maximum Sink Current
ILIMIT
Output FET on, TA = 25°C
–
30
–
mA
300
–
1000
G
Magnetic Characteristics
Magnetic Field6
B
Range of input field
Continued on the next page…
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
OPERATING CHARACTERISTICS (continued): Valid throughout full operating voltage and ambient temperature ranges,
unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit2
Angle Characteristics
Output7
Effective resolution8
Angle Refresh
Rate9
tANG
Response Time10
tRESPONSE
Angle Error11
Angle
–
12
–
bit
B = 300 G, TA = 25ºC, ORATE = 0
–
10.8
–
bits
B ≥ 700 G, TA = 25ºC, ORATE = 0
–
12
–
bits
ORATE = 0
–
32
–
µs
All linearization and computations disabled, see
Figure 1
–
60
–
µs
TA = 25°C, ideal magnet alignment, B = 300 G,
target rpm = 0, no linearization
–
±0.5
–
degrees
TA = 25°C, ideal magnet alignment, B = 900 G,
target rpm = 0, no linearization
–
±0.2
–
degrees
TA = 150°C, ideal magnet alignment, B = 300 G,
target rpm = 0, no linearization
–1.3
–
+1.3
degrees
TA = 150°C, ideal magnet alignment, B = 900 G,
target rpm = 0, no linearization
–
±0.3
–
degrees
TA = 25°C, 50 samples, B = 300 G, no internal
filtering
–
0.2
–
degrees
TA = 150°C, 50 samples, B = 300 G, no internal
filtering
–
0.27
–
degrees
1.4
degrees
RESANGLE
ERRANG
Noise11, 12
NANG
Temperature Drift
ANGLEDRIFT
TA = 150°C, B = 300 G
–1.4
TA = –40°C, B = 300 G
–
±1.2
–
degrees
–
±0.5
–
degrees
ANGLEDRIFT- B = 300 G, typical maximum drift observed after
Angle Drift Over Lifetime
LIFE
AEC Q100 qualification testing
1 Typical
data is at TA = 25°C and VCC = 5 V and it is for design information only.
G (gauss) = 0.1 mT (millitesla).
3 Parameters for this characteristic are determined by design. They are not measured at
final test.
4 End user can customize what power-on tests are conducted at each power-on that
causes a range of power-on times. For more information, see the description
of the CFG register.
5 During the power-on phase, the A1335 SPI transactions are not guaranteed.
6 The A1335 operates in Magnetic fields lower than 300 G, but with reduced accuracy
and resolution.
7 RES
ANGLE represents the number of bits of data available for reading from the die
registers.
8 Effective Resolution is calculated using the formula below:
21
log2 (360) - log2
Magnet
Position
Position 1
Position 2
t
( )
50
l=1
Response Time
l
where σ is the Standard Deviation based on thirty measurements taken at each of the
32 angular positions, I = 11.25, 22.5, … 360.
9 The rate at which a new angle reading is ready. This value varies with the ORATE
selection.
10 This value assumes no post-processing and is the response time to read the magnetic
position with no further computations. Actual response time is dependent on
EEPROM settings. Settings related to filter design, signal path computations, and
linearization will increase the response time.
11 Error 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.
12 One sigma value at 300 G. Operation with a larger magnetic field results in improved
noise performance. For 600 G operation, noise reduced by 40-50% vs. 300 G.
13 Parameter is tested at wafer probe only.
Sensor
Output
Output 1
Output 2
t
Definition of Response Time
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
7
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
FUNCTIONAL DESCRIPTION
Overview
The A1335 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 A1335 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 interface capable of supporting I2C, SPI and SENT, and
digital output of processed angle data.
Advanced linearization, offset, and gain adjustment options
are available in the A1335. 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.
value is calculated.
• Microprocessor The preprocess signal is subjected to various
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, 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:
Table 1: Refresh Rates of Averaged Samples
ORATE
[2:0]
Quantity of Samples
Averaged
Refresh Rate
(µs)
000
1
32
001
2
64
Operation
010
4
128
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 1 for a depiction
of the signal process flow described here.
011
8
256
100
16
512
101
32
1024
110
64
2048
111
128
4096
• 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
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.
P2 Angle Compensation The A1335 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.
P2a 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.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
A1
CVH
Element
A2
Analog Signal
Conditioning
A3
A to D
Converter
D1
Digital Signal
Conditioning
D2
Raw Angle
Computation
Analog
Front End
(Applied Magnetic
Signal Detection)
Digital
Front End
(Digital Logic for
Processing)
P1
Sample Rate
(Resolution)
Angle
Averaging
(Optional)
IR Filter
P1a
Angle
P2 Compensation
P2a
(Optional)
Prelinearization
Rotation
(Optional)
Gain Offset
P3
Minimum/
Maximum
Angle Check*
P4
Gain Adjust*
P2b
Microprocessor
(Angle Processing)
(Optional)
Harmonic
Linearization
(Optional)
P5 Postlinearization
0 Offset
(Optional)
P6 Angle Clamping*
P4b
(Optional)
Prelinearization
0 Offset
P4a
(Optional)
Segmented
Linearization
P4c
SRAM
EEPROM
P5a
(Optional)
Postlinearization
Rotation
P7 Angle Rounding
to 12 Bits
(Optional)
Angle
Inversion
* Short Stroke Applications Only
P7a
Primary Serial Interface
(Optional)
Die Adjust
Figure 1: Signal Processing Flow (refer by index number to text descriptions)
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A1335
P2b Gain Offset (Optional). Allows zeroing out of the angle
prior to applying Gain. Set via the GAIN_OFFSET field. Angle =
Angle - GAIN_OFFSET.
P3 Minimum/Maximum Angle Check (Short Stroke Applications Only). 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). This feature is useful for
applications that use angle strokes less than 360 degrees (short
stroke). (Note: This feature is only active if the Short Stroke bit
has been set.)
P4 Gain Adjust (Short Stroke Applications Only). 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 such that a 45-degree angular change would be
distributed across the entire 4095 → 0 code range. Set using the
GAIN field. (Note: This feature is only active if the Short Stroke
bit has been set.)
P4a Harmonic 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.
P4b Prelinearization 0 Offset (optional but required if
Segmented Linearization is used). The expected angle values
should be distributed throughout the input dynamic range to optimize angle post-processing. This is mostly needed for applications that use full 360-degree rotations. This value establishes the
position that will correspond to zero error. This value should be
set such that the 360 ≥ degree range corresponds to the 4095 ≥ 0
code range. Setting this point is critical if segmented linearization
is used. This is required prior to going through linearization, as
the compensation requires a continuous input function to operate
correctly. Set using the LIN_OFFSET field.
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
P4c Segmented Linearization (Optional). Applies user-programmed error correction coefficients (set in the LINC registers)
to the raw angle measurements. Use the SL bit to enable segmented linearization.
P5 Postlinearization 0 Offset (Optional). 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.
P5a 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.
P6 Angle Clamping (Short Stroke Applications Only). The
A1335 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: This feature is only active if the Short Stroke bit
has been set.)
P7 Angle Rounding to 12 Bits. All of the internal calculations
for angle processing in the A1335 take place with 16-bit precision. This step rounds the data into a 12-bit word for output
through the Primary Serial Interface.
P7a Angle Inversion (Short Stroke Application Only). Rotation within the high and low clamp values. [CLAMP_HI - (Angle
- CLAMP_LO)]. (Note: This feature is only active if the Short
Stroke bit has been set.)
P8 Die Adjust (Optional). Rotates final angle 180 degrees. Used
to compensate for the 180 degree offset between die in dual SoC
packages.
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10
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
Diagnostic Features
The A1335 was designed with diagnostic requirements in mind
and supports many on-chip diagnostics as well as error/status
flags, enabling the host microcontroller to assess the operational
status of each die.
In addition, the A1335 supports three different on-chip userinitiated diagnostics.
USER-INITIATED DIAGNOSTICS
The following three internal self-tests may be configured to run
at power-on, and may also be initiated at any time by the system
microcontroller via Extended Access commands through the
SPI/I2C interface. A failure of any one of the three self-tests will
assert the Self-Test Failure Flag, ST, within the extended error
register. The specific failing test can be identified by performing
an extended address-read (address 0xFFFC).
• CVH Self-Test
The CVH self-test is a signal path diagnostic used to verify
both analog and digital system integrity. Test execution
requires approximately 36 ms, during which time no new
angle measurements will be generated by the sensor. The
test is implemented by changing the transducer switch
configuration from normal mode into a test configuration,
allowing a test current to drive the CVHD in place of the
magnetic field. By changing the direction of the test current
and sequencing different elements within the CVH, the selftest emulates a changing magnetic field angle. The measured
angle is monitored to determine a passing or failing device.
A failure of the CVH self-test will assert the ST flag. If the
self-test was initiated via the Extended Access Command, test
results for the individual Hall elements will be stored in the
SRAM CmdStatus field (0x00) and the primary serial interface
ERD register (0x0E through 0x11).
• SRAM BIST
The SRAM Built-In Self-Test (BIST) verifies proper
functionality of the SRAM. The test may be run in either long
or short mode, and can be configured to halt on error. A failure
of the SRAM BIST will assert the ST flag. When enabled
to run on power-up, the short test mode is used, requiring
approximately 100 µs to complete. For more information on
SRAM BIST options, consult the A1335 programming guide.
Table 2: Status and Error Flags
Fault Condition
Description
Sensor Response
VCC < VCCLOW(TH)(min)
Indicates potential for reduced angle accuracy
UV error flag is set
VCC > 8.8 V
Indicates possible system level power supply failure
OV error flag is set*
Field > MAG_HIGH
MAG_HIGH programmable from 0-1240 G in 40 G steps. Monitors Mag Field
level in case of mechanical failure
MH flag is set
Field < MAG_LOW
MAG_LOW programmable from 0-620 G in 20 G steps. Monitors Mag Field
level in case of mechanical failure
ML flag is set
–60°C > TA > 180°C
Ambient temperature beyond maximum rating detected
TR flag is set
Processor Halt
Monitors digital logic for proper functionality
WT and WC Flags set
Single-Bit EEPROM Error (correctable)
Detects and corrects a single-bit EEPROM Error
ES error flag is set
Multi-Bit EEPROM Error (uncorrectable)
Detects a multi-bit uncorrectable EEPROM ERROR
EU error flag is set
Single-Bit SRAM Error (correctable)
Detects and corrects a single-bit SRAM Error
SS Error flag is set
Multi-Bit SRAM Error (uncorrectable)
Detects a multi-bit uncorrectable SRAM ERROR
SU Error flag is set
Angle-Processing Errors
New angle measurement did not occur within the maximum time allotted.
AT flag is set
Angle Out of Range
Angle value (prior to scaling by Gain) is outside the range set by MIN_ANGLE
and MAX_ANGLE. Short Stroke only.
The AL or AH flag is set
Loss of VCC
Determine if system power was lost. Also detects a reset of the internal
microprocessor
POR and RC flags are set
Self-Test Failure
Indicates a failure of one of the three internal self-tests. SRAM BIST, ROM
Checksum Verification, and CVH self-test. Tests can be individually configured
to run at power-up and may also be user initiated.
ST flag set
* EEPROM programming pulses result in OV flag assertion.
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Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
• ROM Checksum
Verification of the ROM checksum may be configured to take
place at power-on. In addition, the checksum is continuously
recalculated in the background during normal operation
(independent of power-on configuration). This test may be
initiated at any time by the system microcontroller via an
Extended Access Command (0xFFE0). If the self-test was
initiated via the Extended Access Command, the failing
checksum is stored in the CmdStatus SRAM register (0x00). A
bad ROM checksum asserts the Self-Test Failure Flag, ST.
LOW VOLTAGE DETECTION
In addition to setting the undervoltage (UV) flag, a VCC ramp will
also change the state of the output pins (SDA/MISO and SENT)
as the part enters and exits the reset condition. This is shown in
Figure 2.
For more information on diagnostic features and flags, refer to
the programmers guide for a more complete description of the
available flags and settings.
VCC (V)
VCC Low Flag Threshold, VCCLOW(TH)
4.4
POR
3.8
3.7
POR
UV
Error
Flag
Set
UV
Error
Flag
Set
State of SDA/MISO
and SENT Pins
High
Impedance
Angle
Output
Accuracy
Reduced
Accurate
Angle Output
Angle
Output
Accuracy
Reduced
High
Impedance
t
Figure 2: Relationship of VCC and Output
Programming Modes
The EEPROM can be written through the dedicated I2C or SPI
interface pins or via Manchester encoding on the VCC pin, allowing process coefficients to be entered and options selected. (Note:
programming EEPROM also requires the VCC line to be pulsed,
which could adversely affect other devices if powered from the
same line). 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 applica-
tion development and bench-testing. The EEPROM provides
persistent storage at end of line for final parameters. At Power-on
initialization, the EEPROM contents are read into the corresponding SRAM. Provided the Lock Microprocessor [LM] bit within
EEPROM is not set, SRAM can be overwritten during operation
(Use Caution). The EEPROM is permanently locked by setting
the lock EEPROM [LE] bit in the EEPROM.
The A1335 EEPROM is programmed via either the I2C, the SPI,
or the VCC pin Serial Interface, with additional power provided
by pulses on the VCC pin to set the EEPROM bit fields.
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Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
MANCHESTER SERIAL INTERFACE
To facilitate addressable device programming when using the
unidirectional SENT output mode with no need for additional
wiring, the A1335 incorporates a serial interface on the VCC
line. (Note: The A1335 may be programmed via the SPI or I2C
interfaces, with additional wiring connections. For detailed
information on part programming, refer to the A1335 programming manual). This interface allows an external controller to read
and write registers in the A1335 EEPROM and volatile memory.
The device uses a point-to-point communication protocol, based
on Manchester encoding per G.E. Thomas (a rising edge indicates a 0 and a falling edge indicates a 1), with address and data
transmitted MSB first. The addressable Manchester code implementation uses the logic states of the SA0/SA1 pins to set address
values for each die. In this way, individual communication with
up to four A1335 die is possible.
To prevent any undesired programming of the A1335, the serial
interface can be disabled by setting the Disable Manchester bit.
With this bit set, the A1335 will ignore any Manchester input on
VCC.
Entering Manchester Communication Mode
Transaction Types
As shown in Figure 3, the A1335 receives all commands via the
VCC pin, and responds to Read commands via the SENT pin.
This implementation of Manchester encoding requires the communication pulses be within a high (VMAN(H)) and low (VMAN(L))
range of voltages on the VCC line. Writing to EEPROM is supported by two high voltage pulses on the VCC line.
Each transaction is initiated by a command from the controller;
the A1335 does not initiate any transactions. Two commands are
recognized by the A1335: Write and Read.
Writing to EEPROM
When a Write command requires writing to non-volatile
EEPROM, after the Write command, the controller must also
send two Programming pulses, high-voltage strobes via the VCC
pin. These strobes are detected internally, allowing the A1335
to boost the voltage on the EEPROM gates. Refer to the A1335
programming manual for specifics on sensor programming and
protocol details.
Provided the Disable Manchester bit is not set in EEPROM, the
A1335 continuously monitors the VCC line for valid Manchester
commands. The part takes no action until a valid Manchester
Access Code is received.
Write/Read Command Manchester Code
There are two special Manchester code commands used to
activate or deactivate the serial interface and specify the output
format used during Read operations:
1. Manchester Access Code: Enters Manchester Communication Mode; Manchester code output on the SENT pin.
2. Manchester Exit Code; returns the SENT pin to normal
(angle data) output format.
Once the Manchester Communication Mode is entered, the SENT
output pin will cease providing angle data, interrupting any data
transmission in progress.
ECU
VCC
A1335
SENT
Read Manchester Code
GND
Figure 3: Top-Level Programming Interface
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Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
Manchester Interface Reference
Table 3: Manchester Interface Protocol Characteristics1
Characteristics
Symbol
Note
Min.
Typ.
Max.
Unit
Defined by the input message bit rate sent from
the external controller
4
–
100
kbps
243
250
257
µs
Data bit pulse width at 100 kbps
9.5
10
10.5
µs
Deviation in tBIT during one command frame
–11
–
+11
%
VCC <
6.0 V
–
–
–
¼ × tbit
–
¾ × tbit
µs
Delay from last bit cell of write command to start
of EEPROM programming pulse
40
–
–
μs
Input/Output Signal Timing
Bit Rate
Bit Time
tBIT
Bit Time Error
Write Delay
Read Delay
errTBIT
tWRITE(E)
Data bit pulse width at 4 kbps
Required delay from the end of the second
EEPROM Program pulse to the leading edge of
a following command frame
Delay from the trailing edge of a Read
tSTART_READ command frame to the leading edge of the Read
Acknowledge frame
EEPROM Programming Pulse
EEPROM Programming Pulse
Setup Time
tsPULSE(E)
Input Signal Voltage
Manchester Code High Voltage
VMAN(H)
Applied to VCC line
7.8
–
–
V
Manchester Code Low Voltage
VMAN(L)
Applied to VCC line
–
–
5.7
V
Minimum Rpullup = 5 kΩ
0.9 × VS
–
–
V
Maximum Rpullup = 50 kΩ
0.7 × VS
–
–
V
–
–
0.1
V
Output Signal Voltage (Applied on SENT Line)
Manchester Code High Voltage
VMAN(H)
Manchester Code Low Voltage
VMAN(L)
1 Determined
5 kΩ ≤ Rpullup ≤ 50 kΩ
by design.
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Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
SENT Output Mode
The SENT output converts the measured magnetic field angle to
a binary value mapped to the Full-Scale Output (FSO) range of
0 to 4095, shown in Figure 4. This data is inserted into a binary
pulse message, referred to as a frame, that conforms to the SENT
data transmission specification (SAEJ2716 JAN2010).
Angle (°)
The SENT frame may be configured via EEPROM. The A1335
may operate in one of three broadly defined SENT modes (see
the A1335 programming manual for details on SENT modes and
settings).
• SAE J2716 SENT: free-streaming SENT frame in accordance
with industry specification. Additional programmability allows
Tick time adjustment from 0.5 µs to 7.9 µs.
• Triggered SENT (TSENT): User-defined sampling and
retrieval.
• Shared SENT: Allows multiple devices to share a common
SENT line. Devices may either be directly addressed
(Addressable SENT or ASENT) or sequentially polled
(Sequential SENT or SSENT).
4095
(1111 1111 1111)
2048
(1000 0000 0000)
0000
(0000 0000 0000)
SENT Data Value
(LSB)
A1335
Figure 4: Angle is Represented as a 12-bit Digital Value
VCC 5 V Max
Sensor
ID = 0
Sensor
ID = 1
Sensor
ID = 2
Host
(ECU)
Sensor
ID = 3
R
C
Bus Capacitance
Figure 5: Allegro’s proprietary SENT protocol allows
multiple parts to share one common output bus.
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Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
Data within a SENT message frame is represented as a series of
nibbles, with the following characteristics:
The duration of a nibble is denominated in ticks. The period of
a tick is set by the SENT_TICK parameter. The duration of the
nibble is the sum of the low-voltage interval plus the high-voltage
interval.
• Each nibble is an ordered pair of a low-voltage interval
followed by a high-voltage interval
The parts of a SENT message are arranged in the following
required sequence (see Figure 7):
• The low-voltage interval acts as the delimiting state which acts
as a boundary between each nibble. The length of this lowvoltage interval is fixed at 5 ticks.
1. Synchronization and Calibration: Flags the start of the
SENT message.
2. Status and Communication Nibble: Provides A1335 status
and the optional serial data determined by the setting of the
SENT_SERIAL parameter.
3. Data: Angle information and optional data.
4. CRC: Error checking.
5. Pause Pulse (optional): Fill pulse between SENT message
frames.
SENT MESSAGE STRUCTURE
• The high-voltage interval performs the job of the information
state and is variable in duration in order to contain the data
payload of the nibble
• The slew rate of the falling edge may be adjusted using the
SENT_DRIVER parameter.
0
5
12
0
Ticks
5
27
Table 4: Nibble Composition and Value
Ticks
Message
Signal
Voltage
Quantity of Ticks
Message
Signal
Voltage
Low
High
Interval Interval
Low
Interval
Nibble Data Value = 0000
Total
Binary
(4-bit)
Value
Decimal
Equivalent
Value
7
12
0000
0
5
8
13
0001
1
5
9
14
0002
2
LowVoltage
Interval
HighVoltage
Interval
5
High
Interval
Nibble Data Value = 1111
Figure 6: General Value Formation for SENT
5
21
26
1110
14
0000 (left), 1111 (right)
5
22
27
1111
15
SENT_FIXED
SENT_FIXED
56 ticks
Nibble Name
Synchronization
and Calibration
SENT_FIXED
12 to 27
ticks
Status and
Communication
12 to 27
ticks
Data 1
(MSB)
SENT_FIXED
SENT_FIXED
SENT_FIXED
12 to 27
ticks
12 to 27
ticks
Data 6
CRC
Pause
Pulse
(optional)
tSENT
Figure 7: General Format for SENT Message Frame
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Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
APPLICATION INFORMATION
Serial Interface Description
The A1335 features I2C-, SPI-, and SENT-compliant interfaces
for communication with a host microcontroller, or Master. A basic
circuit for configuring the A1335 package is shown in Figure 8.
VCC = 5 V
VCC
0.1 µF
0.1 µF
BYP
A1335
SA1
Host/Master
Microprocessor
BYP
0.1 µF
SCLK
MOSI
A1335
MISO
ISEL
ISEL
AGND
AGND
DGND
DGND
DGND
SDA
(A) Typical A1335 configuration using I2C interface;
A1335 set up for serial address 0xC
DGND
DGND
DGND
SCL
AGND
AGND
Host/Master
Microprocessor
1 kΩ
VCC
CS
SA0
1 kΩ
0.1 µF
(B) Typical A1335 configuration using SPI interface
VCC = 5 V
3.3 V
0.1 µF
VCC
BYP
SA0
5 kΩ
Host/Master
Microprocessor
SA1
0.1 µF
A1335
SENT
SCLK
AGND
AGND
MISO
ISEL
DGND
DGND
DGND
3.3 V
VCC
(C) Typical A1335 configuration using SENT interface (SA0/SA1 may be brought
to BYP or GND to configure Manchester/Shared SENT address)
Figure 8: Typical A1335 configuration
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Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
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 13 to Figure 16 illustrate on- and off-axis sensing configurations.
Table 5: Target Magnet Parameters
Magnetic Material
Diameter
(mm)
Thickness
(mm)
Neodymium (bonded)
15
4
Neodymium
(sintered)*
10
4
Neodymium (sintered)
8
3
Neodymium / SmCo
6
2.5
FIELD STRENGTH
The A1335 actively measures and adapts to its magnetic environment. This allows the operation within a large range of field
strengths (300 to 1000 G). Due to the greater signal-to-noise ratio
provided at higher field strengths, performance inherently increases
with increasing field strength. Typical angle performance over
applied field strength is shown in Figure 9 and Figure 10.
Diameter
*A sintered Neodymium magnet with 10 mm (or greater) diameter and 4 mm thickness is
the recommended magnet for redundant applications.
1.5
25ºC
150ºC
1
Recommended Operating Range
(300 to 1000 G)
0.5
14
13
12
0
100
11
200
300
400
500
600
700
Field Strength in Gauss
800
900
10
1000
Angle Error (±°)
Angle Error in Degrees
S
N
Thickness
Figure 9: Typical Maximum Angle Error
Over Field Strength
9
8
7
6
5
4
3
2
1
25ºC
150ºC
0.9
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)
0.8
0.7
Noise in Degrees
1
0.6
Figure 11: Simulated Error versus Eccentricity for a
10 mm × 4 mm Neodymium magnet at a 2.7 mm air gap.
Recommended Operating Range
(300 to 1000 G)
0.5
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.
0.4
0.3
0.2
0.1
0
100
200
300
400
500
600
700
Field Strength in Gauss
800
900
1000
Figure 10: Typical One Sigma Angle Noise
Over Field Strength
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A1335
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
ON-AXIS APPLICATIONS
Some common on-axis applications for the device include digital
potentiometer, motor sensing, power steering, and throttle sensing. The A1335 is designed to operate with magnets constructed
with a variety of magnetic materials, cylindrical geometries, and
field strengths, as shown in Table 5. 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.
(a)
S
N
OFF-AXIS APPLICATIONS
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 nonlinearity 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.
(b)
Figure 12: Typical On-Axis (a) and
Off-Axis (b) Orientation
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Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
Effect of Orientation on Signal
+|B|
0G
Figure 13: The magnetic field flux lines run between the north pole and south pole of the magnet. The peak flux
densities are between the poles.
360°
+|B|
Detected
Rotation
Magnetic
Flux
0G
Zero
Crossing
90°
180°
270°
0°
360°
Figure 14: 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).
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Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
Hall element
Figure 15: Centering the axis of magnet rotation on the Hall element provides the strongest signal in all degrees
of rotation.
daxial(on-axis)
Axis of
Rotation
daxial(off-axis)
AG (off axis)
AG (on axis)
AG (on axis, centered)
Magnetic
Flux Lines
Figure 16: 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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Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
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 A1335.
The A1335 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 17 graphically illustrates
the general concept.
Harmonic linearization uses 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 using a
Meter and
Sender
sum of ideal periodic waveforms. The A1335 is capable of using
up to 11 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 18 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 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, 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 17: 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, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
22
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
Figure 18: Correction for Eccentric Orientation
∆daxial
∆daxial =
+ phase,
+ amplitude
∆daxial
∆daxial
∆daxial =
+ phase,
+ + amplitude
∆daxial
∆daxial =
+ phase,
– amplitude
∆daxial =
+ phase,
– – amplitude
360
n
ge
t
Fu
nc
tio
n
180
n
io
M
ag
ne
tic
In
p
Li
ut
ne
a
riz
at
In
ve
rs
Ta
r
io
Figure 18a: With the axis of
rotation aligned with the Hall
element, linearization coefficients are a simple inversion
of the input.
Detected Angle (°)
270
90
0
Error Correction (V)
0
Figure 18b: Any eccentricity is evaluated as an error.
Systematic eccentricity can
be factored out by appropriate linearization coefficients.
For off-axis applications,
the harmonic linearization
method is recommended.
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, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
23
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
HARMONIC COEFFICIENTS
PCB Layout
The device supports up to 11 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
Maximum Full Scale Input
io
n
ct
un
tf
2432
on
cti
A
–xLIN_3
n
t fu
u
Inp
–640
ut
pu
A
xLIN_10
A Coefficients stored in
BIN16
0
BIN10
BIN3
BIN2
O
BIN1
BIN0 Minimum Full Scale Input
Magnetic Input Values
(15 x-axis values read
and used to calculate
coefficients)
EEPROM
Figure 19: Sample of Linearization Function Transfer Characteristic
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
24
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
TYPICAL PERFORMANCE CHARACTERISTICS
1
0.8
0.6
Angle Error
0.4
0.2
0
−0.2
−0.4
−0.6
−0.8
−1
0
50
100
150
200
250
Encoder Position
300
350
Figure 20: Typical Angle Error versus Encoder Position
(300 G, 25ºC)
2
1.8
1.6
1.6
1.4
1.4
1.2
1.2
1
0.8
0.6
1
0.8
0.6
0.4
0.4
0.2
0.2
0
−40
−20
0
20
40
60
80
Temperature (ºC)
100
120
140
Figure 21: Peak Angle Error over Temperature
(300 G)
Mean
±3 Sigma
1.8
Drift in Degrees
Angle Error in Degrees
2
Mean
±3 Sigma
0
−40
−20
0
20
40
60
80
Temperature (ºC)
100
120
140
Figure 22: Maximum Absolute Drift from 25ºC Reading
(300 G)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
25
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
35
1
150ºC
25ºC
–40ºC
30
0.8
A1335 Noise in Degrees
Frequency (%)
25
20
15
10
0.7
0.6
0.5
0.4
0.3
0.2
5
0.1
0
0
0.2
0.4
0.6
Noise in Degrees
0.8
18
0
1
Figure 23: Noise Distribution over Temperature
(VCC = 5.5 V)
0
50
100
Ambient Temperature (ºC)
150
Figure 24: Noise Performance over Temperature
(1 Sigma, 300 G)
20
150ºC
25ºC
–40ºC
16
Mean
±3 Sigma
19
14
18
A1335 ICC in mA
12
Count (%)
Mean
±3 Sigma
0.9
10
8
6
17
16
15
14
4
13
2
0
12
13
14
15
16
ICC in mA
17
18
19
Figure 25: ICC Distribution over Temperature
(VCC = 5.5 V)
20
12
0
50
100
Ambient Temperature (ºC)
150
Figure 26: ICC over Temperature
(VCC = 5.5 V)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
26
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
PACKAGE OUTLINE DRAWINGS
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
1.59
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 27: Package LE, 14-Pin TSSOP (Single Die Version)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
27
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
For Reference Only – Not for Tooling Use
(Reference MO-153 AD)
Dimensions in millimeters – NOT TO SCALE
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
7.80±0.10
D
3.40
E
D
1.00
24
0.65
0.45
8º
0º
24
0.20
0.09
D E1
E2 D
4.40±0.10 6.40 BSC
D 2.20
6.10
+0.15
0.60 –0.10
A
1.00 REF
1.65
1
2
1
2
0.25 BSC
C
24X
1.10 MAX
0.10 C
0.30
0.19
SEATING
PLANE
SEATING PLANE
GAUGE PLANE
B
PCB Layout Reference View
0.65 BSC
0.15
0.05
A
Terminal #1 mark area
B
Reference land pattern layout (reference IPC7351 TSOP65P640X120-25M);
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 can improve thermal dissipation
(reference EIA/JEDEC Standard JESD51-5)
NNNNNNNNNN
YYWW
LLLL
1
C
C
Branding scale and appearance at supplier discretion
D
Hall elements (E1, E2), corresponding to respective die; not to scale
E
Active Area Depth 0.36 mm REF
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 28: Package LE, 24-Pin TSSOP (Dual Die Version)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
28
Precision Hall-Effect Angle Sensor IC
with I2C, SPI, and SENT Interfaces
A1335
Revision
Change
–
Initial release
1
Updated Angle Characteristics; reduced SENT and Manchester information
redundant with A1335 programming guide; added Field Strength section and
charts; added on-axis and off-axis figures; corrected CVH location in single-die
package outline drawing.
Pages
Responsible
Date
All
W. Wilkinson
September 21, 2015
1, 7,
19, 20,
27
W. Wilkinson
December 17, 2015
Copyright ©2015, Allegro MicroSystems, LLC
Allegro MicroSystems, LLC 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, LLC assumes no responsibility for its
use; nor for any infringement of patents or other rights of third parties which may result from its use.
I2C™ is a trademark of Philips Semiconductors.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
29
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