MagAlpha MAQ470
12-Bit, Automotive Angle Sensor
with ABZ Incremental & PWM Outputs
DESCRIPTION
FEATURES
The MAQ470 detects the absolute angular
position of a permanent magnet, typically a
diametrically magnetized cylinder on a rotating
shaft. Fast data acquisition and processing
provide accurate angle measurement at speeds
from 0 to 60,000 rpm.
The MAQ470 supports a wide range of
magnetic
field
strengths
and
spatial
configurations. Both end-of-shaft and off-axis
(side-shaft mounting) configurations
are
supported.
The MAQ470 features magnetic field strength
detection with programmable thresholds to
allow sensing of the magnet position relative to
the sensor for creation of functions such as the
sensing of axial movements or for diagnostics.
On-chip non-volatile memory provides storage
for configuration parameters, including the
reference zero angle position, ABZ encoder
settings, and magnetic field detection
thresholds.
12-Bit Resolution Absolute Angle Encoder
Contactless Sensing for Long Life
AEC-Q100 Qualified
Simple and Robust Design
SPI Serial Interface with Parity Bit for Angle
Readout and Chip Configuration
Configuration Programmable Magnetic Field
Strength Detection for Diagnostic Checks
Incremental 10-Bit ABZ Quadrature
Encoder Interface with Programmable
Pulses Per Turn from 1-256
PWM Output 12-Bit
3.3V, 12mA Supply
-40°C to +150°C Operating Temperature
Available in a QFN-16 (3mmx3mm)
Package with Wettable Flanks
APPLICATIONS
Automotive
Angle Encoders
Automotive Angle or Speed Sensors
Robotics
All MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. For
MPS green status, please visit the MPS website under Quality Assurance. “MPS”
and “The Future of Analog IC Technology” are registered trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
MAQ470 Rev. 1.1
6/22/2021
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1
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
ORDERING INFORMATION
Part Number*
MAQ470GQE-AEC1
Package
QFN-16 (3mmx3mm)
Top Marking
See Below
* For Tape & Reel, add suffix -Z (e.g. MAQ470GQE-AEC1-Z)
TOP MARKING
BDC: Product code of MAQ470GQE
Y: Year code
LLL: Lot number
PACKAGE REFERENCE
TOP VIEW
QFN-16 (3mmx3mm)
MAQ470 Rev. 1.1
6/22/2021
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2
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
PIN FUNCTIONS
Package
Pin #
1
2
3
4
5
6
Name
Description
SSD
A
Z
MOSI
CS
B
Data out (SSI).
Incremental output.
Incremental output.
Data in (SPI). MOSI has an internal pull-down resistor.
Chip select (SPI). CS has an internal pull-up resistor.
Incremental output.
Data out (SPI). MISO has an internal pull-down resistor that is enabled at a high
impedance state.
Supply ground.
PWM output.
Connect to ground.
Digital output indicating field strength below MGLT level.
Clock (SPI). SCLK has an internal pull-down resistor.
Supply 3.3V.
No connection. Leave NC unconnected.
Clock (SSI). SSCK has an internal pull-down resistor.
Digital output indicating field strength above MGHT level.
7
MISO
8
9
10
11
12
13
14
15
16
GND
PWM
TEST
MGL
SCLK
VDD
NC
SSCK
MGH
ABSOLUTE MAXIMUM RATINGS (1)
Supply voltage ............................. -0.5V to +4.6V
Input pin voltage (VI) .................... -0.5V to +6.0V
Output pin voltage (VO) ................ -0.5V to +4.6V
Continuous power dissipation (TA = +25°C) (2)
..................................................................... 2.0W
Junction temperature ................................ 160°C
Lead temperature...................................... 260°C
Storage temperature ................... -65°C to 160°C
MAQ470 Rev. 1.1
6/22/2021
Thermal Resistance (3)
θJA
θJC
QFN-16 (3mmx3mm) ............. 50 ...... 12 ... °C/W
NOTES:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD (MAX) = (TJ
(MAX)-TA)/θJA.
3) Measured on JESD51-7, 4-layer PCB.
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3
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
ELECTRICAL CHARACTERISTICS
Parameter
Symbol Condition
Recommended Operating Conditions
Supply voltage
VDD
Supply current
Operating temperature
Applied magnetic field
MAQ470 Rev. 1.1
6/22/2021
IDD
Top
B
From -40°C to +125°C
Min
Typ
Max
Units
3.0
3.3
3.6
V
10.2
11.7
13.8
mA
-40
30
125
60
°C
mT
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4
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
GENERAL CHARACTERISTICS
VDD = 3.3V, 45mT < B < 100mT, Temp = -40°C to +125°C, unless otherwise noted.
Parameter
Absolute Output – Serial
Symbol
Effective resolution
Condition
Min
Typ
Max
Units
3σ deviation of the noise
distribution
11.0
11.8
12.8
bit
0.01
850
16
0.02
980
0.03
1100
16
deg
kHz
bit
12
ms
10
µs
Noise RMS
Refresh rate
Data output length
Response Time
Power-up time (4)
Constant speed propagation
delay
Latency (4)
Filter cutoff frequency (4)
Accuracy
8
Fcutoff
390
Hz
INL at 25°C
At room temperature over the full
field range
0.7
deg
INL between -40°C to
+125°C (5)
Over the full temperature range
and field range
1.1
deg
INL at 150°C
over the full field range
1.16
deg
0.015
deg/°C
0.5
1.0
0.005
deg
deg
deg/mT
deg/V
Output Drift
Temperature induced drift at
room temperature (5)
From 25°C to 85°C
From 25°C to 125°C
Temperature induced
variation (5)
Magnetic field induced (5)
Voltage supply induced (5)
Absolute Output - PWM
PWM frequency
PWM resolution
Incremental Output – ABZ
ABZ update rate
Resolution - edges per turn
Pulses per channel per turn
ABZ hysteresis (5)
Systematic jitter
(5)
Random jitter (3σ)
Overall ABZ jitter (5)
MAQ470 Rev. 1.1
6/22/2021
Fpwm
204
11.0
240
11.8
264
12.0
16
PPT+1
H
Programmable
Programmable
4
1
For PPT = 255, between 0 and
100krpm, up to 60mT
For PPT = 127, between 0 and
100krpm
For PPT = 255, between 0 and
100krpm
For PPT = 127, between 0 and
100krpm
Up to 60mT
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Hz
bit
MHz
1024
256
0.7
deg
13
%
7
%
5.5
%
2.8
%
0.3
deg
5
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
GENERAL CHARACTERISTICS (continued)
VDD = 3.3V, 45mT < B < 100mT, Temp = -40°C to +125°C, unless otherwise noted.
Parameter
Symbol Condition
Magnetic Field Detection Thresholds
Accuracy (5)
Hysteresis (5)
MagHys
(5)
Temperature drift
Digital I/O
Input high voltage
Input low voltage
Output low
voltage (5)
Output high voltage
(5)
Pull-down resistor
rate (4)
Rising edge slew
Falling edge slew rate
(4)
VIH
VIL
VOL
VOH
RPD
TR
TF
Min
Typ
5
6
-600
2.5
-0.3
CL = 50pF
CL = 50pF
2.4
43
Units
mT
mT
ppm/°C
5.5
0.8
0.4
IOL = 4mA
IOH = 4mA
Max
V
V
V
V
55
0.7
0.7
97
kΩ
V/ns
V/ns
NOTES:
4) Guaranteed by design.
5) Guaranteed by characteristic test.
MAQ470 Rev. 1.1
6/22/2021
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6
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
TYPICAL CHARACTERISTICS
VDD = 3.3V, Temp = 25°C, unless otherwise noted.
ABZ Jitter at PPT = 255
Noise Spectrum at 50mT
6
Filter Transfer Function
0.01
5
4
3
0
FILTER TRANSFER FUNCTION (dB)
1/2
NOISE DENSITY (deg/Hz )
RANDOM JITTER (%)
5
0.001
0.0001
-3 dB
-5
-10
-15
2
-20
10
10
1
0.1
1
10
100
1000
10
4
10
10
5
100
4
1000
4
10
10
5
1000
10
10
f (Hz)
5
FREQUENCY (Hz)
ROTATION SPEED (rpm)
Non-Linearity (INL and
Harmonics)
Error Curves at 50mT
Effective Resolution (3σ)
1.5
12
2
11.5
NON-LINEARITY (deg)
-45癈
0
-1
EFFECTIVE RESOLUTION (bit)
INL
25癈
125癈
1
ERROR (deg)
100
-5
1
H1
0.5
H2
11
10.5
10
9.5
9
8.5
-2
8
0
0
50
100
150
200
250
300
350
0
20
40
60
MAGNETIC FIELD (T)
ANGLE (deg)
80
100
0
20
40
60
80
100
120
MAGNETIC FIELD (mT)
Current Consumption at
VDD = 3.3V
12
SUPPLY CURRENT (mA)
11.5
11
10.5
10
-50
0
50
100
150
TEMPERATURE (癈 )
MAQ470 Rev. 1.1
6/22/2021
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MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
BLOCK DIAGRAM
Figure 1: Functional Block Diagram
MAQ470 Rev. 1.1
6/22/2021
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MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
OPERATION
Sensor Front-End
The magnetic field is detected with integrated
Hall devices located in the center of the
package. The angle is measured using the
SpinaxisTM method, which digitizes the direction
of the field directly without complex arctangent
computation or feedback loop-based circuits
(interpolators).
The SpinaxisTM method is based on phase
detection and generates a sinusoidal signal with
a phase that represents the angle of the
magnetic field. The angle is then obtained by a
time-to-digital converter, which measures the
time between the zero crossing of the
sinusoidal signal and the edge of a constant
waveform (see Figure 2). The time-to-digital is
output from the front-end to the digital
conditioning block.
Sensor – Magnet Mounting
The sensitive volume of the MAQ470 is
confined in a region less than 100µm wide and
has multiple integrated Hall devices. This
volume is located both horizontally and
vertically within 50µm of the center of the QFN
package. The sensor detects the angle of the
magnetic field projected in a plane parallel to
the package’s upper surface. This means that
the only relevant magnetic field is the in-plane
component (X and Y components) in the middle
point of the package.
By default, when looking at the top of the
package, the angle increases when the
magnetic field rotates clockwise. Figure 3
shows the zero angle of the unprogrammed
sensor, where the cross indicates the sensitive
point. Both the rotation direction and the zero
angle can be programmed.
Top: Sine Waveform
Bottom: Clock of Time-to-Digital Converter
Figure 2: Phase Detection Method
The output of the front-end delivers a digital
number proportional to the angle of the
magnetic field at the rate of 1MHz in a
straightforward and open-loop manner.
Digital Filtering
The front-end signal is further treated to
achieve the final effective resolution. This
treatment does not add any latency in steady
conditions. The filter transfer function can be
calculated with Equation (1):
H (s)
1 2s
(1 s ) 2
(1)
Where τ is the filter time constant related to the
cutoff frequency by: τ = 0.38/Fcutoff. See the
General Characteristics table on page 5 for the
value of Fcutoff.
MAQ470 Rev. 1.1
6/22/2021
Figure 3: Detection Point and Default Positive
Direction
This type of detection provides flexibility for the
design of an angular encoder. The sensor only
requires the magnetic vector to lie essentially
within the sensor plane with a field amplitude of
at least 30mT. Note that the MAQ470 can work
with fields smaller than 30mT, but the linearity
and resolution performance may deviate from
the specifications. The most straightforward
mounting method is to place the MAQ470
sensor on the rotation axis of a permanent
magnet (i.e.: a diametrically magnetized
cylinder) (see Figure 4). The recommended
magnet is a Neodymium alloy (N35) cylinder
with dimensions Ø5x3mm inserted into an
aluminum shaft with a 1.5mm air gap between
the magnet and the sensor (surface of
package). For good linearity, the sensor is
positioned with a precision of 0.5mm.
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MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
In general, the MagAlpha works well with or
without the exposed pad connected. For
optimum conditions (electrically, thermally, and
mechanically), it is recommended that the
exposed pad be connected to ground.
Figure 4: End-of-Shaft Mounting
If the end-of-shaft position is not available, the
sensor can be positioned away from the
rotation axis of a cylinder or ring magnet (see
Figure 5). In this case, the magnetic field angle
is no longer directly proportional to the
mechanical angle. The MAQ470 can be
adjusted to compensate for this effect and
recover the linear relation between the
mechanical angle and the sensor output. With
multiple pole pair magnets, the MAQ470
indicates multiple rotations for each mechanical
turn.
Figure 5: Side-Shaft Mounting
Electrical Mounting and Power Supply
Decoupling
It is recommended to place a 1µF decoupling
capacitor close to the sensor with a low
impedance path to GND (see Figure 6).
Serial Interface
The sensor supports the SPI serial interface for
angle reading and register programming.
Alternatively, the SSI bus can be used for angle
reading (programming through SSI is not
supported).
Data length is 16 bit. For checking the integrity
of the data received (angle or register content)
the master shall send a 17th clock count and
receive a parity bit.
SPI
SPI is a four-wire, synchronous, serial
communication interface. The MagAlpha
supports SPI Mode 3 and Mode 0 (see Table 1
and Table 2). The SPI Mode (0 or 3) is detected
automatically by the sensor and therefore does
not require any action from the user. The
maximum clock rate supported on SPI is
25MHz. There is no minimum clock rate. Note
that real-life data rates depend on the PCB
layout quality and signal trace length. See
Figure 7 and Table 3 for SPI timing.
All commands to the MagAlpha (whether for
writing or reading register content) must be
transferred through the SPI MOSI pin and must
be 16-bit long.
See the SPI Communication section on page
13 for details.
Table 1: SPI Specification
SCLK idle state
Data capture
Data transmission
CS idle state
Data order
Mode 0
Mode 3
Low
High
On SCLK rising edge
On SCLK falling edge
High
MSB first
Table 2: SPI Standard
Figure 6: Connection for Supply Decoupling
MAQ470 Rev. 1.1
6/22/2021
CPOL
CPHA
Data Order (DORD)
Mode 0
Mode 3
0
1
0
1
0 (MSB first)
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MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
tcsL
CS
tsclk
tsclkL tsclkH
tcsH
tMISO
tMISO
tidleAngle
tidleReg
tnvm
SCLK
tMISO
MISO
hi-Z
MOSI
MSB
X
LSB
MSB
hi-Z
MSB
X
LSB
MSB
tMOSI
Figure 7: SPI Timing Diagram
tidleAngle
tidleAngle
tidleAngle
tidleReg
tidleReg
tidleAngle
tnvm
tidleReg
CS
MISO
Angle
Angle
Angle
Angle
Reg Value
Angle
Angle
Reg Value
Angle
MOSI
0
0
0
Read Reg Cmd
0
0
Write Reg Cmd
0
0
Figure 8: Minimum Idle Time
Table 3: SPI Timing
Parameter
(6)
Description
Min
Max
tidleAngle
Idle time between two subsequent angle transmissions
150
ns
tidleReg
Idle time before and after a register readout
750
ns
tnvm
Idle time between a write command and a register readout
(delay necessary for non-volatile memory update)
20
ms
tcsL
Time between CS falling edge and SCLK falling edge
80
ns
tsclk
SCLK period
40
ns
tsclkL
Low level of SCLK signal
20
ns
tsclkH
High level of SCLK signal
20
ns
tcsH
Time between SCLK rising edge and CS rising edge
25
ns
tMISO
SCLK setting edge to data output valid
tMOSI
Data input valid to SCLK reading edge
15
15
Unit
ns
ns
NOTE:
6) All values are guaranteed by design.
MAQ470 Rev. 1.1
6/22/2021
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11
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
SPI Communication
The sensor supports three types of SPI
operation:
Read angle
Read configuration register
Write configuration register
Angle reading can be therefore optimized,
without any loss of information, by reducing the
number of clock counts. In the case of a 12-bit
data output length, only 12 clock counts are
required to get the full sensor resolution.
LSB
MSB
Each operation has a specific frame structure
described below.
SPI Read Angle
Every 1µs, new data is transferred into the
output buffer. The master device triggers the
reading by pulling CS low.
When a trigger event is detected, the data
remains in the output buffer until the CS signal
is de-asserted (see Table 4).
MISO
Angle(15:4)
MOSI
0
If less resolution is needed, the angle can be
read by sending even fewer clock counts (since
the MSB is first).
In case of fast reading, the MagAlpha continues
sending the same data until the data is
refreshed. See the refresh rate section in the
General Characteristics table on page 5.
Table 4: Sensor Data Timing
Event
Action
Start reading and freeze
CS falling edge
output buffer
CS rising edge
Release of the output buffer
See Figure 9 for a diagram of a full SPI angle
reading. See Figure 10 for a partial SPI angle
reading. A full angle reading requires 16 clock
pulses. The sensor MISO line returns:
MSB
LSB
MISO
Angle(15:0)
MOSI
0
The MagAlpha family has sensors with different
features and levels of resolution. See the data
output length section in the General
Characteristics table on page 5 for the number
of useful bits delivered at the serial output. If the
data length is smaller than 16, the rest of the
bits sent are zeros. For example, a data output
length of 12 bits means that the serial output
delivers a 12-bit angle value with four bits of
zeros padded at the end (MISO state remains
zero). If the master sends 16 clock counts, the
MagApha replies with:
LSB
MSB
MISO
MOSI
MAQ470 Rev. 1.1
6/22/2021
Angle(15:4)
Figure 9: Diagram of a Full 16-Bit SPI Angle
Reading
Figure 10: Diagram of a Partial 8-Bit SPI Angle
Reading
0 0 0 0
0
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MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
SPI Read Register
A read register operation is constituted of two
16-bit frames. The first frame sends a read
request, which contains the 3-bit read
command (010) followed by the 5-bit register
address. The last 8 bits of the frame must be all
set to 0. The second frame returns the 8-bit
register value (MSB byte).
MSB
See Figure 11 for a complete transmission
overview.
For example, to get the value of the magnetic
level high and low flags (MGH and MGL), read
register 27 (bit 6, bit 7) by sending the following
first frame:
MISO
LSB
Angle(15:0)
LSB
Angle(15:0)
MOSI
command
reg. address
MOSI 0 1 0 A4 A3 A2 A1 A0
0 0 0 0 0 0 0 0
reg. value
MISO V7 V6 V5 V4 V3 V2 V1 V0
command
0 1 0
reg. address
1 1 0 1 1
0 0 0 0 0 0 0 0
LSB
0 0 0 0 0 0 0 0
In the second frame, the MagAlpha replies:
reg. value
MISO MGH MGL X X X X X X
Second 16-bit SPI frame (response):
MSB
0
MSB
First 16-bit SPI frame (read request):
MISO
MOSI
0 0 0 0 0 0 0 0
MSB
MOSI
LSB
0
See Figure 12 for a complete example overview.
Figure 11: Two 16-Bit Frames Read Register Operation
Figure 12: Example Read Magnetic Level Flags High and Low (MGH, MGH) on Register 27, Bit 7-6
MAQ470 Rev. 1.1
6/22/2021
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13
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
SPI Write Register
Table 7 shows the programmable 8-bit registers.
Data written to these registers are stored in the
on-chip non-volatile memory and reloaded at
power-on automatically. The factory default
register values are shown in Table 8.
A write register operation is constituted of two
16-bit frames. The first frame sends a write
request, which contains the 3-bit write
command (100) followed by the 5-bit register
address and the 8-bit value (MSB first). The
second frame returns the newly written register
value (acknowledge).
The on-chip memory is guaranteed to endure
1,000 write cycles at 25°C.
It is critical to wait 20ms between the first and
the second frame. This is the time taken to write
the non-volatile memory. Failure to implement
this wait period results in the register’s previous
value being read. Note that this delay is only
required after a write request. A read register
request and read angle do not require this wait
time.
The second 16-bit SPI frame (response) is:
reg. value
MISO V7 V6 V5 V4 V3 V2 V1 V0
MSB
MSB
LSB
MOSI
0
The read-back register content can be used to
verify the register programming. See Figure 13
for a complete transmission overview.
For example, to set the value of the output
rotation direction (RD) to counterclockwise
(high). Write register 9 by sending the following
first frame:
MSB
MISO
MOSI
LSB
Angle(15:0)
command
1 0 0
reg. address
0 1 0 0 1
reg. value
1 0 0 0 0 0 0 0
Send the second frame after a 20ms wait time.
If the register is written correctly, the reply is:
reg. value
MISO 1 0 0 0 0 0 0 0
The first 16-bit SPI frame (write request) is:
MISO
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
MSB
LSB
Angle(15:0)
MOSI
LSB
0
See Figure 14 for a complete example.
command
reg. address
reg. value
MOSI 1 0 0 A4 A3 A2 A1 A0 V7 V6 V5 V4 V3 V2 V1 V0
Figure 13: Overview of Two 16-Bit Frames Write Register Operation
MAQ470 Rev. 1.1
6/22/2021
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14
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
Figure 14: Example Write Output Rotation Direction (RD) to Counterclockwise (High), on Register 9, Bit 7
SSI
SSI is a 2-wire synchronous serial interface for
data reading only. The sensor operates as a
slave to the external SSI master and supports
only angle reading. It is not possible to read or
write registers by SSI.
SSI Communication
Unlike SPI, the sensor SSI only supports angle
reading operation. It is not possible to read or
write registers using SSI. SSI timing
communication is shown in Figure 15 and Table
5.
Figure 15: SSI Timing
Table 5: SSI Timing
Parameter
Description
Min
tssd
Max
Unit
15
ns
tssck
SSCK period
0.04
16
µs
tssckL
Low level of SSCK signal
0.02
8
µs
tssckH
High level of SSCK signal
0.02
8
µs
tm
Transfer timeout (monoflop time)
25
µs
tp
Dead time: SSCK high time for next data reading
40
µs
SSI Read Angle
The bit order of the transmitted data is MSB first
and LSB last. Every 1µs, new data is
transferred into the output buffer. The master
device triggers the reading by driving SSCK
high. A full reading requires up to 17 clock
counts (see Figure 16).
MAQ470 Rev. 1.1
6/22/2021
The first clock is a dummy clock to start the
transmission. The data length is up to 16 bits
long. See the data output length section in the
General Characteristics table on page 5 for the
number of useful bits delivered at the serial
output.
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15
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
The first data MSB is transmitted on the second
clock count. If the data length is less than 16,
the 16-bit output word is completed by zeros.
Therefore, the reading can also be performed
with fewer than 16 clock counts. For example,
for a part with a 12-bit data length, it is only
necessary to send the first dummy clock to start
the transmission + 12 clocks to read the angle
data.
When a trigger event is detected, the data
remains in the output buffer until the clock
falling edge for the LSB bit 0 and the transfer
timeout time has passed (see Table 6).
Table 6: Sensor Data Timing
Trigger Event
Release of the Output Buffer
First SSCK pulse rising
edge
SSCK falling edge + time out tm (Fig 15)
Figure 16: Diagram of a Full 16-Bit SSI Angle Reading (with First Dummy Clock)
For consecutive angle readings, see the timing in Figure 17.
Figure 17: Diagram of Two Consecutive 16-Bit SSI Angle Reading with the Required Dead Time between
the Frames
Parity bit
The parity bit, or check bit, is added to the output string to ensure that the total number of 1’s in the
string is even. It is used as error detecting code for angle or register reading. The MagAlpha transmits
the parity bit at the 17th clock edge. See table 7 and figure 18
Table 7: Example of Parity bit
Number of
16-bits output
bits set to
Output with the parity bit
"1"
0
0000000000000000
00000000000000000
6
1000110001100010
10001100011000100
5
0101110100000000
01011101000000001
MAQ470 Rev. 1.1
6/22/2021
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16
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
CS
6
5
4
3
2
1
0
Parity
7
6
5
4
3
2
1
0
7
8
9
10
11
12
13
14
8
9
10
11
12
13
14
15
MOSI
Angle
16
MISO
15
SCLK
0
Figure 18: SPI Angle reading with parity bit
MAQ470 Rev. 1.1
6/22/2021
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17
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
REGISTER MAP
Table 8: Register Map
No
Hex
Bit 7
MSB
Bin
Bit 6
Bit 5
Bit 4
Bit 3
0
0x0
00000
Z(7:0)
1
0x1
00001
Z(15:8)
2
0x2
00010
BCT(7:0)
3
0x3
00011
4
0x4
00100
5
0x5
00101
6
0x6
00110
9
0x9
01001
RD
-
27
0x1B
11011
MGH
MGL
-
-
-
-
PPT(1:0)
-
Bit 2
Bit 1
Bit 0
LSB
-
ETY
ETX
-
-
-
-
-
-
-
-
ILIP(3:0)
-
PPT(7:2)
MGLT(2:0)
MGHT(2:0)
-
-
-
-
MIR(3:0)
Table 9: Factory Default Values
No
Hex
Bin
Bit 7
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
LSB
0
0x0
00000
0
0
0
0
0
0
0
0
1
0x1
00001
0
0
0
0
0
0
0
0
2
0x2
00010
0
0
0
0
0
0
0
0
3
0x3
00011
0
0
0
0
0
0
0
0
4
0x4
00100
1
1
0
0
0
0
0
0
5
0x5
00101
0
0
1
1
1
1
1
1
6
0x6
00110
0
0
0
1
1
1
0
0
9
0x9
01001
0
0
0
0
0
0
0
0
Table 10: Programming Parameters
Parameters
Symbol
Zero Setting
Bias Current
Trimming
Z
Number of
Bits
16
BCT
8
Enable Trimming X
ETX
1
Enable Trimming Y
ETY
1
Pulses Per Turn
PPT
8
ILIP
Index Length /
Index Position
Magnetic Field
High Threshold
Magnetic Field Low
Threshold
Rotation Direction
Magnetic field In
Range
MAQ470 Rev. 1.1
6/22/2021
Description
See Table
Set the zero position
For side-shaft configuration: reduce the
bias current of the X or Y Hall device
Biased current trimmed in the X direction
Hall device
Biased current trimmed in the Y direction
Hall device
Number of pulses per turn of the ABZ
output
11
4
Parametrization of the ABZ index pulse
Fig 26
MGHT
3
Sets the field strength high threshold
17
MGLT
3
Sets the field strength low threshold
17
RD
1
13
MIR
3
Determines the sensor positive direction
Indicates that the measured field level is
correct
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15
15
18
20
18
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
REGISTER SETTINGS
Zero Setting
The zero position of the MagAlpha (a0) can be
programmed with 16 bits of resolution. The
angle streamed out by the MagAlpha (aout) is
given by Equation (2):
aout araw a0
(2)
Where araw is the raw angle provided by the
MagAlpha front end.
The parameter Z(15:0), which is zero by default,
is the complementary angle of the zero setting.
In decimals, it can be written as shown in
Equation (3):
a 0 216 Z (15 : 0)
(3)
Table 11 shows the zero setting parameter.
Example
To set the zero position to 20 degrees, the
Z(15:0) parameter must be equal to the
complementary angle and can be calculated
with Equation (4):
20 deg 16
2 61895
360 deg
Table 13: Rotation Direction Parameter
RD
0
1
Positive Direction
Clockwise (CW)
Counterclockwise (CCW)
BCT Settings (Bias Current Trimming)
Side Shaft
When the MAQ470 is mounted on the side of
the magnet, the relation between the field angle
and the mechanical angle is no longer directly
linear. This effect is related to the fact that the
tangential magnetic field is usually smaller than
the radial field. Define the field ratio k with
Equation (5):
Table 11: Zero Setting Parameter
Zero pos.
Zero pos.
Z(15:0)
a0 (deg)
a0 (16 bit dec)
0
65536
360.000
1
65535
359.995
2
65534
359.989
…
…
…
65534
2
0.011
65535
1
0.005
Z (15 : 0) 216
Figure 19: Positive Rotation Direction of the
Magnetic Field
k Brad / Btan
(5)
Where Brad and Btan are the maximum radial and
tangential magnetic fields (see Figure 20).
(4)
In binary, it is written as 1111 0001 1100 0111.
Table 12 shows the content of the registers 0
and 1.
Table 12: Register 0 and 1 Content
Reg Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0
1
1
0
0
0
1
1
1
1
1
1
1
1
0
0
0
1
Rotation Direction
By default, when looking at the top of the
package, the angle increases when the
magnetic field rotates clockwise (CW) (see
Figure 19 and Table 13).
MAQ470 Rev. 1.1
6/22/2021
Figure 20: Side-Shaft Field
The ratio k depends on the magnet geometry
and the distance to the sensor. Having a k ratio
different than 1 results in the sensor output
response not being linear with respect to the
mechanical angle. Note that the error curve has
the shape of a double sinewave (see Figure 22).
E is the amplitude of this error.
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19
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
The X-axis or the Y-axis bias current can be
reduced by programming in order to recover an
equal Hall signal for all angles and therefore
suppress the error. The parameter ETX and
ETY controls the direction in which sensitivity is
reduced. The current reduction is set by the
parameter bias current trimming BCT(7:0),
which is an integer from 0 to 255.
In side-shaft configuration (i.e.: the sensor
center is located beyond the magnet outer
diameter), k is greater than 1. For optimum
compensation, the sensitivity of the radial axis
should be reduced by setting the BCT
parameter as shown in Equation (6):
1
BCT (7 : 0) 2581
k
(6)
The graph in Figure 21 shows the optimum
BCT value for a particular k ratio.
200
BCT
150
Table 14: Example of BCT Settings
BCT(7:0)
E (deg)
Magnet Ratio k
0
1.0
0
11.5
1.5
86
19.5
2.0
129
25.4
2.5
155
30.0
3.0
172
33.7
3.5
184
36.9
4.0
194
39.5
4.5
201
41.8
5.0
207
Determining k with the MagAlpha
It is possible to deduce the k ratio from the error
curve obtained with the default BCT setting
(BCT = 0). For this purpose, rotate the magnet
over one revolution and record the MagAlpha
output. Then plot the error curve (the MagAlpha
output minus the real mechanical position vs
the real mechanical position) and extract two
parameters: the maximum error E and the
position of this maximum with respect to a zero
crossing am (see Figure 22). k can be calculated
with Equation (7):
k
100
tan( E a m )
tan(a m )
(7)
40
50
20
0
1.5
2
2.5
3
3.5
4
4.5
5
k
Figure 21: Relation between the k Ratio and the
Optimum BCT to Recover Linearity
2E
m
Error (deg)
1
0
-20
Table 14 shows some typical BCT values.
-40
0
50
100
150
200
250
300
350
rotor angle (deg)
Figure 22: Error Curve in Side-Shaft
Configuration with BCT = 0
Some examples are given in Table 14.
Alternatively, the k parameter can be obtained
from the graph of Figure 23.
MAQ470 Rev. 1.1
6/22/2021
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20
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
Magnetic Field Thresholds
The magnetic flags (MGL and MGH) indicate
that the magnetic field at the sensor position is
out a range defined by the lower (MGLT) and
upper magnetic field thresholds (MGHT) (see
Figure 25).
5
4.5
4
k
3.5
3
2.5
2
1.5
1
0
5
10
15
20
25
30
35
40
E (deg)
Figure 23: Relation between the Error Measured
with BCT = 0 and the Magnet Ratio k
Sensor Orientation
From the dot marked on the package, it is
possible to know whether the radial field is
aligned with the sensor coordinate X or Y (see
Figure 24).
Figure 25: MGH and MGL Signals as a Function
of the Field Strength
MagHys, the typical hysteresis on the signals
MGH and MGL is 6mT. The MGLT and MGHT
thresholds are coded on three bits and stored in
register 6 (see Table 16).
Table 16: Register 6
Register 6
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
MGLT
MGHT
-
The 3-bit values of MGLT and MGHT
correspond to the magnetic field (see Table 17).
Figure 24: Package Top View with X and Y Axes
Determine which axis needs to be reduced (see
the qualitative field distribution around a ring in
Figure 20). For instance, with the arrangement
depicted in Figure 24, the field along the sensor
Y direction is tangential and weaker. The X-axis
should be reduced (ETX = 1 and ETY = 0).
Note that if both ETX and ETY are set to 1, the
current bias is reduced in both directions the
same way (i.e.: without side-shaft correction)
(see Table 15).
Table 15: Trimming Direction Parameters
ETX
Enable Trimming of the X-Axis
0
Disabled
1
Enabled
ETY
Enable Trimming of the Y-Axis
0
Disabled
1
Enabled
MAQ470 Rev. 1.1
6/22/2021
Table 17: MGLT and MGHT: Binary to mT
Relation
MGLT or
MGHT (8)
000
001
010
011
100
101
110
111
Field threshold in mT (7)
From low to high
magnetic field
26
41
56
70
84
98
112
126
From high to low
magnetic field
20
35
50
64
78
92
106
120
NOTES:
7) Valid for VDD=3.3V. If different then field threshold is scaled
by the factor VDD/3.3V.
8) MGLT can have a larger value than MGHT.
The alarm flags MGL and MGH are available to
be read in register 27 (bit 6, bit 7), and their
logic state is also given at the digital output pins
11 and 16.
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21
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
To read the MGL and MGH flags by SPI send
the 8-bit command write into register 27:
command
0 1 0
reg. address
1 1 0 1 1
value
LSB
0 0 0 0 0 0 0 0
MSB
The MAQ470 answers with the register 27
content in the next transmission:
MGH MGL
R[7:0]
x
x
x
x
x
x
ABZ Incremental Encoder Output
The MAQ470 ABZ output emulates a 10-bit
incremental encoder (such as an optical
encoder) providing logic pulses in quadrature
(see Figure 26). Compared to signal A, signal B
is shifted by a quarter of the pulse period. Over
one revolution, signal A pulses N times, where
N is programmable from 1 to 256 pulses per
revolution. The number of pulses per channel
per revolution is programmed by setting the
parameter PPT, which consists of eight bits split
between registers 0x4 and 0x5 (see Table 8).
The factory default value is 256. Table 18
describes how to program PPT(7:0) to set the
required resolution.
Table 18: PPT
Pulses per Edges per
Turn
Turn
1
4
2
8
3
12
4
16
…
…
253
1012
254
1016
255
1020
256
1024
PPT(7:0)
00000000
00000001
00000010
00000011
…
11111100
11111101
11111110
11111111
Figure 26: Timing of the ABZ Output
Signal Z (zero or index) raises only once per
turn at the zero-angle position.
The position and length of the Z pulse is
programmable via bits ILIP(3:0) in register 0x5
(see Figure 27).
Figure 27: ILIP Parameter Effect on Index Shape
MIN
…
MAX
By default, the ILIP parameter is 0000. The
index rising edge is aligned with the channel B
falling edge. The index length is half the A or B
pulse length.
ABZ Hysteresis
A hysteresis larger than the output noise is
introduced on the ABZ output to avoid any
spurious transitions (see Figure 28).
For example, to set 120 pulses per revolution
(i.e.: 480 edges), set PPT to 120 - 1 = 119. In
binary: 01110111. Thus the registers 4 and 5
must be set as shown in Table 19.
Table 19: Example PPT Setting for 120 Pulses
R4
R5
B7
1
0
B6
1
0
B5
0
0
B4
0
1
B3
0
1
B2
0
1
B1
0
0
B0
0
1
Figure 28: Hysteresis of the Incremental Output
MAQ470 Rev. 1.1
6/22/2021
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MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
ABZ Jitter
The ABZ state is updated at a frequency of
16MHz, enabling accurate operation up to a
very high rpm (above 105 rpm).
The angle can be calculated with Equation (8):
The jitter characterizes how far a particular ABZ
edge can occur at an angular position different
from the ideal position (see Figure 29).
Figure 30 shows one period of the PWM signal.
The period T is 1/Fpwm, where Fpwm is the
PWM frequency indicated in the General
Characteristics table.
angle(in deg) 360
t ON
1
130
1 (8)
128
t ON t OFF
Figure 29: ABZ Jitter
The measurable jitter is composed by a
systematic jitter (i.e.: always the same deviation
at a given angle) and a random jitter.
The random jitter reflects the sensor noise.
Therefore, the edge distribution is the same as
the SPI output noise. Like the sensor resolution,
it is defined as the 3σ width of this distribution.
In fact, the random jitter is a function of the
rotation speed. At a lower speed, the random
jitter is smaller than the sensor noise.
This is a consequence of the fact that the
probability of measuring an edge at a certain
distance from the ideal position depends on the
number of ABZ updates at this position.
The minimum field for ABZ reading is 30mT.
PWM Absolute Output
This output provides a logic signal with a duty
cycle proportional to the angle of the magnetic
field. The PWM frequency is indicated in the
General Characteristics table on page 5. The
duty cycle is bounded by a minimum value
(1/130 of the period) and a maximum value
(129/130 of the period) (see Figure 30), so the
duty cycle varies from 1/130 to 129/130 with a
resolution of 12 bits. The angle can be retrieved
by measuring the on time. Since the absolute
PWM frequency can vary from chip to chip or
with the temperature, accurate angle detection
requires the measurement of the duty cycle (i.e.:
the measurement of both the on time (ton) and
the off time (toff)).
MAQ470 Rev. 1.1
6/22/2021
Top Signal: 0°
Bottom Signal: Full Scale (i.e.: 360°(1-1/4096))
Figure 30: PWM Output Timing
Diagnostic Features
The following feature can be used to determine
correct functional operation of the sensor.
1) Parity bit on the angle (see description
of the parity bit on page 16 )
2) Magnetic Field in Range via MIR(3:0)
Magnetic Field In Range
The bits MIR(3:0) in register 27 can be used to
verify that the magnetic field is between the
thresholds set by MGLT(2:0) and MGHT(2:0) in
register 6. The value of MIR(3:0) will be 0011
when the field is between these thresholds.
This also indicates that the Hall sensor front
end is functioning correctly and acquiring angle
samples.
For example: Assuming MGLT(2:0) is left at the
default value of 00 representing 15mT, and the
MGHT(2:0) is left at 111 representing 126mT,
then if the field strength is between these
values, the MIR(3:0) value will be 0011.
For the above default threshold settings, values
of MIR(3:0)can be decoded as shown in table
20.
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23
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
Table 20: MIR(3:0) logic states
MIR(3:0)
0011
1111
0000
0001
0010
0100
1000
1001
1010
1011
1100
1101
MAQ470 Rev. 1.1
6/22/2021
Conditions MGLT(2:0) at default of 15mT, MGHT(2:0) at default of 126mT
Field in range and Hall sensor array operational
Field above MAGH and MAGL threshold – magnet too close to sensor
Field below MAGH and MAGL threshold – magnet too far away / missing
Invalid state : Hall array sensor functional error
Invalid state : Hall array sensor functional error
Invalid state : Hall array sensor functional error
Invalid state : Hall array sensor functional error
Invalid state : Hall array sensor functional error
Invalid state : Hall array sensor functional error
Invalid state : Hall array sensor functional error
Invalid state : Hall array sensor functional error
Invalid state : Hall array sensor functional error
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24
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
TYPICAL APPLICATION CIRCUITS
Figure 31: Typical Configurations Using SPI Interface and MGH/MGL Signals
Figure 32: Typical Configuration Using ABZ Interface
MAQ470 Rev. 1.1
6/22/2021
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25
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
PACKAGE INFORMATION
QFN-16 (3mmx3mm)
MAQ470 Rev. 1.1
6/22/2021
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26
MAQ470 – 12-BIT, AUTOMOTIVE ANGLE SENSOR WITH ABZ & PWM OUTPUTS
APPENDIX A: DEFINITIONS
This is the smallest angle increment distinguishable from the noise. The
Effective Resolution (3σ resolution is measured by computing three times σ (the standard
deviation in degrees) taken over 1,000 data points at a constant position.
noise level)
The resolution in bits is obtained with: log2(360/6σ).
Refresh Rate
Rate at which new data points are stored in the output buffer.
ABZ Update Rate
Rate at which a new ABZ state is computed. The inverse of this rate is
the minimum time between two ABZ edges.
Latency
The time elapsed between the instant when the data is ready to be read
and the instant at which the shaft passes that position. The lag in
, where is the angular velocity in deg/s.
degrees is
Power-Up Time
Time until the sensor delivers valid data starting at power up.
Maximum deviation between the average sensor output (at a fixed
position) and the true mechanical angle.
400
sensor out (deg)
350
300
lag
250
ideal
sensor output
200
150
INL
100
Integral
(INL)
Non-Linearity
0
sensor out
best straight fit
resolution
( ? 3 )
50
0
100
200
300
400
500
600
700
rotor position (deg)
Figure A1: Resolution, INL, Lag
INL can be obtained from the error curve
, where
is the average over 1000 sensor output and is the mechanical
angle indicated by a high precision encoder (
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