MagAlpha MA710
12-Bit, Digital, Contactless Angle Sensor
with ABZ Incremental & PWM Outputs
DESCRIPTION
FEATURES
The MA710 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 MA710 is particularly suitable for low
magnetic
field
applications:
side-shaft
configuration or the use of non-rare earth
magnets.
12-Bit Resolution Absolute Angle Encoder
15mT Minimum Magnetic Field
Contactless Sensing for Long Life
SPI Serial Interface for Digital Angle
Readout and Chip Configuration
Incremental
10-Bit
ABZ
Quadrature
Encoder Interface with Programmable
Pulses Per Turn from 1-256
PWM Output 12-Bit
Programmable Magnetic Field Strength
Detection for Diagnostic Checks
3.3V, 12mA Supply
-40°C to +125°C Operating Temperature
Available in a QFN-16 (3mmx3mm)
Package
The MA710 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.
APPLICATIONS
General Purpose Angle Measurement
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
MA710 Rev. 1.0
9/27/2017
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1
MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS
ORDERING INFORMATION
Part Number*
MA710GQ
Package
QFN-16 (3mmx3mm)
Top Marking
See Below
* For Tape & Reel, add suffix –Z (e.g. MA710GQ–Z)
TOP MARKING
AYZ: Product code of MA710GQ
Y: Year code
LLL: Lot number
PACKAGE REFERENCE
TOP VIEW
QFN-16 (3mmx3mm)
MA710 Rev. 01.0
9/27/2017
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MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance
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
(2)
Continuous power dissipation (TA = +25°C)
..................................................................2.0W
Junction temperature ............................... 125°C
Lead temperature .................................... 260°C
Storage temperature .................. -65°C to 150°C
QFN-16 (3mmx3mm) ............ 50 ....... 12 ... °C/W
MA710 Rev. 01.0
9/27/2017
(3)
θJA
θJC
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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MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS
ELECTRICAL CHARACTERISTICS
Parameter
Symbol Condition
Recommended Operating Conditions
Min
Typ
Max
Units
Supply voltage
3.0
3.3
3.6
V
10.2
11.7
13.8
mA
125
°C
mT
VDD
Supply current
IDD
Operating temperature
Applied magnetic field
Top
B
MA710 Rev. 01.0
9/27/2017
From -40°C to +125°C
-40
15
60
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MA710 – 12-BIT, DIGITAL 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 Condition
3σ deviation of the noise
distribution
3σ deviation of the noise
distribution
Effective resolution
Effective resolution at 15mT
(5)
Noise RMS
Refresh rate
Data output length
Response Time
Min
Typ
Max
Units
12.0
12.8
13.8
bit
10.5
11.0
11.5
Bit
0.004
850
14
0.008
980
0.015
1100
14
deg
kHz
bit
60
10
93
ms
µs
Hz
0.7
deg
1.1
deg
(4)
Power-up time
(4)
Latency
(4)
Filter cutoff frequency
Accuracy
Constant speed propagation delay
8
Fcutoff
At room temperature over the full
field range
Over the full temperature range
and field range
INL at 25°C
INL between -40°C to
(5)
+125°C
Output Drift
Temperature induced drift at
(5)
room temperature
From 25°C to 85°C
From 25°C to 125°C
Temperature induced
(5)
variation
(5)
Magnetic field induced
(5)
Voltage supply induced
Absolute Output - PWM
PWM frequency
PWM resolution
Incremental Output – ABZ
ABZ update rate
Resolution - edges per turn
Pulses per channel per turn
(5)
ABZ hysteresis
Systematic jitter
(5)
Random jitter (3σ)
Overall ABZ jitter
MA710 Rev. 01.0
9/27/2017
(5)
0.015
0.04
deg/°C
0.5
1.0
1.2
2.1
deg
deg
0.3
deg/mT
deg/V
264
12.0
Hz
bit
0.005
Fpwm
204
11.0
240
11.8
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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MHz
1024
256
0.7
deg
13
%
7
%
5.5
%
2.8
%
0.3
deg
5
MA710 – 12-BIT, DIGITAL 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
Min
(5)
Accuracy
(5)
Hysteresis
(5)
Temperature drift
Digital I/O
Input low voltage
Output low voltage
(5)
Output high voltage
(5)
Pull-down resistor
(4)
Rising edge slew rate
(4)
Falling edge slew rate
Max
5
6
-600
MagHys
Input high voltage
Typ
VIH
VIL
VOL
VOH
RPD
2.5
-0.3
IOL = 4mA
TR
TF
CL = 50pF
CL = 50pF
IOH = 4mA
2.4
43
Units
mT
mT
ppm/°C
5.5
0.8
0.4
V
97
kΩ
V
V
V
55
0.7
0.7
V/ns
V/ns
NOTES:
4) Guaranteed by design.
5) Guaranteed by characteristic test.
MA710 Rev. 01.0
9/27/2017
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MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS
TYPICAL CHARACTERISTICS
VDD = 3.3V, Temp = 25°C, unless otherwise noted.
Noise Spectrum at
50mT
ABZ Jitter at PPT = 255
Filter Transfer Function
0.01
6
5
FILTER TRANSFER FUNCTION (dB)
RANDOM JITTER (%)
1/2
NOISE DENSITY (deg/Hz )
5
4
3
0.001
0
-3 dB
-5
-10
-15
2
1
-20
0.0001
0.1
1
10
100
1000
10
4
10
5
0.1
1
10
ROTATION SPEED (rpm)
100
1000
10
4
1
10
100
10
4
f (Hz)
FREQUENCY (Hz)
Non-Linearity (INL and
Harmonics)
Error Curves at 50mT
1000
Effective Resolution
(3σ)
13
1.5
2
125癈
NON-LINEARITY (deg)
ERROR (deg)
1
EFFECTIVE RESOLUTION (bit)
12
INL
25癈
-45癈
0
1
H1
0.5
-1
H2
11
10
9
-2
8
0
0
0
50
100
150
200
250
300
350
0
20
40
60
80
20
40
60
80
100
120
100
MAGNETIC FIELD (mT)
ANGLE (deg)
MAGNETIC FIELD (T)
Current Consumption at
VDD = 3.3V
12
SUPPLY CURRENT (mA)
11.5
11
10.5
10
-50
0
50
100
150
TEMPERATURE (癈 )
MA710 Rev. 01.0
9/27/2017
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MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS
PIN FUNCTIONS
Package
Pin #
Name
1
2
SSD
A
Data out (SSI).
Incremental output.
3
4
5
6
Z
MOSI
CS
B
7
MISO
8
9
10
GND
PWM
TEST
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.
11
12
13
14
15
16
MGL
SCLK
VDD
NC
SSCK
MGH
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.
MA710 Rev. 01.0
9/27/2017
Description
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MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS
BLOCK DIAGRAM
VDD
MA710
NVM
CS
Registers
SCLK
MISO
Spinaxis front-end
BP
2D Hall effect
device
Phase
detection
Digital
conditioning
Amplitude
detection
Serial
interface
MOSI
SSCK
SSD
A
ABZ
encoder
PWM
B
Z
PWM
MGL
MGH
GND
Figure 1: Functional Block Diagram
MA710 Rev. 01.0
9/27/2017
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MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW 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 MA710 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.
MA710 Rev. 1.0
9/27/2017
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 15mT. The most straightforward
mounting method is to place the MA710 sensor
on the rotation axis of a permanent magnet (i.e.:
a diametrically magnetized cylinder) (see Figure
4). A typical magnet is a cylinder with
dimensions Ø5x3mm inserted into an aluminum
shaft with an air gap between the magnet and
the sensor (surface of package) of 1.5mm. A
broad variety of magnet material can be
selected, from hard ferrite to NdFeB. (producing
a field at the sensor position of about 20mT and
80mT, respectively, with typical material grade).
For good linearity, the sensor is positioned with
a precision of 0.5mm.
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MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
In general, the MagAlpha works well with or
without the exposed pad connected to anything.
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 MA710 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 MA710 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).
3.3 V
MGL MGH
A
B
VDD
Z
MISO
MOSI
1 mF
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).
SPI
SPI is a 4-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
Table 2: SPI Standard
SCLK
MA710
CS
GND
SSCK
SSD
TEST
Exposed pad
Mode 0
Mode 3
Low
High
On SCLK rising edge
On SCLK falling edge
High
MSB first
CPOL
CPHA
Data Order (DORD)
Mode 0
Mode 3
0
1
0
1
0 (MSB first)
PWM
Figure 6: Connection for Supply Decoupling
MA710 Rev. 1.0
9/27/2017
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MA710 – 12-BIT, DIGITAL 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.
MA710 Rev. 1.0
9/27/2017
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MA710 – 12-BIT, DIGITAL 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.
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).
LSB
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
CS falling edge
CS rising edge
Action
Start reading and freeze
output buffer
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:
MSB
MISO
MOSI
MA710 Rev. 1.0
9/27/2017
LSB
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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MA710 – 12-BIT, DIGITAL 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 eight bits of the frame must
be all set to 0. The second frame returns the 8bit register value (MSB byte).
MOSI
0
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:
MSB
The first 16-bit SPI frame (read request) is:
MSB
MISO
MISO
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
The second 16-bit SPI frame (response) is:
MSB
LSB
Angle(15:0)
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
MA710 Rev. 1.0
9/27/2017
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MA710 – 12-BIT, DIGITAL 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 68.
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
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:
MSB
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
MSB
LSB
MISO
Angle(15:0)
MOSI
command
reg. address
reg. value
1 0 0 A4 A3 A2 A1 A0 V7 V6 V5 V4 V3 V2 V1 V0
MOSI
LSB
0
See Figure 14 for a complete example.
Figure 13: Overview of Two 16-Bit Frames Write Register Operation
MA710 Rev. 1.0
9/27/2017
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MA710 – 12-BIT, DIGITAL 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).
MA710 Rev. 1.0
9/27/2017
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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MA710 – 12-BIT, DIGITAL 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
MA710 Rev. 1.0
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MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS
REGISTER MAP
Table 5: Register Map
Bit 7
MSB
Bit 6
Bit 0
LSB
-
ETY
ETX
-
-
-
-
-
-
-
-
-
-
-
Bin
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
-
-
-
-
Bit 4
Bit 1
Hex
-
Bit 5
Bit 2
No
-
PPT(1:0)
-
Bit 3
ILIP(3:0)
-
PPT(7:2)
MGLT(2:0)
MGHT(2:0)
Table 6: 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 7: Programming Parameters
Parameters
Symbol
Number of
Bits
Zero Setting
Bias Current
Trimming
Z
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
MA710 Rev. 1.0
9/27/2017
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
10
4
Parametrization of the ABZ index pulse
Fig 26
MGHT
3
Sets the field strength high threshold
16
MGLT
3
Sets the field strength low threshold
16
RD
1
Determines the sensor positive direction
12
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14
14
17
18
MA710 – 12-BIT, DIGITAL 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):
a0 216 Z (15 : 0)
(3)
Table 10: Zero Setting Parameter
0
1
2
…
65534
65535
Zero pos.
a0 (16 bit dec)
65536
65535
65534
…
2
1
Zero pos.
a0 (deg)
360.000
359.995
359.989
…
0.011
0.005
Example
To set the zero position to 20 degrees, the
Z(15:0) parameter shall be equal to the
complementary angle and can be calculated
with Equation (4):
Z (15 : 0) 216
20 deg 16
2 61895
360 deg
Table 12: Rotation Direction Parameter
RD
0
1
Positive Direction
Clockwise (CW)
Counterclockwise (CCW)
BCT Settings (Bias Current Trimming)
Side Shaft
When the MA710 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 10 shows the zero setting parameter.
Z(15:0)
Figure 15: 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 19).
(4)
In binary, it is written as 1111 0001 1100 0111.
Table 11 shows the content of the registers 0
and 1.
Table 11: Register 0 and 1 Content
Reg Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
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 18 and Table 12).
MA710 Rev. 1.0
9/27/2017
Figure 16: Side-Shaft Field
The ratio k depends on the magnet geometry
and the distance to the sensor. Having a k ratio
different than one 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 21).
E is the amplitude of this error.
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MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS
Table 13: Example of BCT Settings
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 20 shows the optimum
BCT value for a particular k ratio.
200
E (deg)
0
11.5
19.5
25.4
30.0
33.7
36.9
39.5
41.8
Magnet Ratio k
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
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 21). k can be calculated
with Equation (7):
150
BCT
BCT(7:0)
0
86
129
155
172
184
194
201
207
k
100
tan(E a m )
tan(a m )
(7)
40
50
20
0
2E
1.5
2
2.5
3
3.5
4
4.5
5
k
Figure 17: Relation between the k Ratio and the
Optimum BCT to Recover Linearity
Error (deg)
m
1
0
-20
Table 13 shows some typical BCT values.
-40
0
50
100
150
200
250
300
350
rotor angle (deg)
Figure 21: Error Curve in Side-Shaft
Configuration with BCT = 0
Some examples are given in Table 13.
Alternatively, the k parameter can be obtained
from the graph of Figure 22.
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MA710 – 12-BIT, DIGITAL 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 24).
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 22: 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 23).
Figure 19: 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 15).
Table 15: 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 16).
Figure 18: 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 19). For instance, with the arrangement
depicted in Figure 23, 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 14).
Table 14: Trimming Direction Parameters
ETX
0
1
ETY
0
1
MA710 Rev. 1.0
9/27/2017
Enable Trimming of the X-Axis
Disabled
Enabled
Enable Trimming of the Y-Axis
Disabled
Enabled
Table 16: MGLT and MGHT: Binary to mT
Relation
MGLT or
(8)
MGHT
000
001
010
011
100
101
110
111
Field threshold in mT
From low to high
magnetic. field
26
41
56
70
84
98
112
126
(7)
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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MA710 – 12-BIT, DIGITAL 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 MA710 answers with the register 27
content in the next transmission:
MGH MGL
x
R[7:0]
x
x
x
x
x
ABZ Incremental Encoder Output
The MA710 ABZ output emulates a 10-bit
incremental encoder (such as an optical
encoder) providing logic pulses in quadrature
(see Figure 25). 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 8 bits split
between registers 0x4 and 0x5 (see Table 7).
The factory default value is 256. Table 17
describes how to program PPT(7:0) to set the
required resolution.
Figure 25: 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 26).
Table 17: PPT
Pulses per
Turn
1
2
3
4
…
253
254
255
256
PPT(7:0)
00000000
00000001
00000010
00000011
…
11111100
11111101
11111110
11111111
Edges per
Turn
4
8
12
16
…
1012
1016
1020
1024
Figure 26: 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 27).
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 18.
Table 18: 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 27: Hysteresis of the Incremental Output
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MA710 – 12-BIT, DIGITAL 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 jitter characterizes how far a particular ABZ
edge can occur at an angular position different
from the ideal position (see Figure 28).
The angle can be calculated with Equation (8):
angle (in deg) 360
t ON
1
130
1 (8)
128
t ON t OFF
Figure 29, shows one period of the PWM signal.
The period T is 1/Fpwm, where Fpwm is the
PWM frequency indicated in the general
characteristic table.
Figure 28: 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.
Top Signal: 0°
Bottom Signal: Full Scale (i.e.: 360°(1-1/4096))
Figure 29: PWM Output Timing
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. 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 29), 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)).
MA710 Rev. 1.0
9/27/2017
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MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS
TYPICAL APPLICATION CIRCUITS
Figure 30: Typical Configurations Using SPI Interface and MGH/MGL Signals
Figure 31: Typical Configuration Using ABZ Interface
MA710 Rev. 1.0
9/27/2017
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MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS
PACKAGE INFORMATION
QFN-16 (3mmx3mm)
MA710 Rev. 1.0
9/27/2017
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MA710 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & PWM OUTPUTS
APPENDIX A: DEFINITIONS
Effective Resolution (3σ
noise level)
This is the smallest angle increment distinguishable from the noise. The
resolution is measured by computing three times σ (the standard
deviation in degrees) taken over 1,000 data points at a constant position.
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
degrees is
, where 𝑣 is the angular velocity in deg/s.
Power-Up Time
Time until the sensor delivers valid data starting at power up.
Integral Non-Linearity
(INL)
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
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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