MagAlpha MA310
12-Bit, Digital, Contactless Angle Sensor
with ABZ & UVW Incremental Outputs
DESCRIPTION
FEATURES
The MA310 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 MA310 is particularly suitable for low
magnetic
field
applications:
side-shaft
configuration or the use of non-rare earth
magnets.
The MA310 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 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, UVW pole pair emulation settings, and
magnetic field detection thresholds.
12-Bit Resolution Absolute Angle Encoder
15mT Minimum Magnetic Field
SPI Serial Interface for Digital Angle
Readout and Chip Configuration
Incremental 10-Bit ABZ Quadrature
Encoder Interface with Programmable
Pulses Per Turn from 1 to 256
UVW Interface with 1 to 8 Pole Pair
Emulation
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
APPLICATIONS
Brushless DC Motor Servo Drives
Motor Commutation
Motor Speed and Position Control
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
MA310 Rev. 1.0
9/22/2017
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
ORDERING INFORMATION
Part Number*
MA310GQ
Package
QFN-16 (3mmx3mm)
Top Marking
See Below
* For Tape & Reel, add suffix –Z (e.g. MA310GQ–Z)
TOP MARKING
AYV: Product code of MA310GQ
Y: Year code
LLL: Lot number
PACKAGE REFERENCE
TOP VIEW
QFN-16 (3mmx3mm)
MA310 Rev. 1.0
9/22/2017
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance (3)
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 ............................... 125°C
Lead temperature .................................... 260°C
Storage temperature .................. -65°C to 150°C
QFN-16 (3mmx3mm) ............ 50 ....... 12 ... °C/W
MA310 Rev. 1.0
9/22/2017
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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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
ELECTRICAL CHARACTERISTICS
Parameter
Symbol Condition
Recommended Operating Conditions
Min
Typ
Max
Units
Supply voltage
VDD
3.0
3.3
3.6
V
Supply current
IDD
10.2
11.7
13.8
mA
Operating temperature
Applied magnetic field
Top
B
125
°C
mT
MA310 Rev. 1.0
9/22/2017
From -40°C to +125°C
-40
15
50
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW 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
ms
10
µs
Power-up time (4)
Constant speed propagation
delay
Latency (5)
Filter cutoff frequency (4)
Accuracy
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
+125°C (5)
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)
Incremental Output – ABZ
ABZ update rate
Resolution - edges per turn
Pulses per channel per turn
ABZ hysteresis (5)
93
Hz
0.7
deg
1.1
deg
0.015
0.04
deg/°C
0.5
1.0
1.2
2.1
deg
deg
0.3
deg/mT
deg/V
0.005
16
PPT+1
H
Systematic jitter (5)
Random jitter (3σ)
Overall ABZ jitter (5)
Programmable
Programmable
4
1
MHz
1024
256
0.7
deg
For PPT = 255, between 0 and
100krpm, up to 60mT
13
%
For PPT = 127, between 0 and
100krpm
7
%
For PPT = 255, between 0 and
100krpm
5.5
%
For PPT = 127, between 0 and
100krpm
2.8
%
Up to 60mT
0.3
deg
8
0.7
0.3
deg
deg
Incremental Output – UVW
Cycle per turn
UVW hysteresis (5)
UVW jitter (3σ) (5)
MA310 Rev. 1.0
9/22/2017
NPP
H
1
0.1
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW 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)
Temperature drift (5)
Digital I/O
Input low voltage
voltage (5)
Output high
voltage (5)
Pull-down resistor
Rising edge slew
rate (4)
Falling edge slew rate
(4)
Typ
Max
5
6
-600
MagHys
Input high voltage
Output low
Min
2.5
-0.3
Units
mT
mT
ppm/°C
VIH
VIL
VOL
VOH
RPD
IOL = 4mA
TR
CL = 50pF
0.7
V/ns
TF
CL = 50pF
0.7
V/ns
IOH = 4mA
2.4
43
5.5
0.8
0.4
V
V
V
V
55
97
kΩ
NOTES:
4) Guaranteed by design.
5) Guaranteed by characteristic test.
MA310 Rev. 1.0
9/22/2017
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
TYPICAL CHARACTERISTICS
VDD = 3.3V, Temp = 25°C, unless otherwise noted.
ABZ Jitter at PPT = 255
Noise Spectrum at 50mT
Filter Transfer Function
5
6
FILTER TRANSFER FUNCTION (dB)
0.01
1/2
NOISE DENSITY (deg/Hz )
RANDOM JITTER (%)
5
4
3
0.001
0
-3 dB
-5
-10
-15
2
-20
0.0001
1
0.1
1
10
100
1000
10
4
10
5
1
0.1
1
10
100
1000
10
10
100
1000
10
4
4
f (Hz)
FREQUENCY (Hz)
ROTATION SPEED (rpm)
Non-Linearity
(INL and harmonics)
Error Curves at 50mT
Effective Resolution (3σ)
1.5
13
2
12
-45°C
0
-1
EFFECTIVE RESOLUTION (bit)
NON-LINEARITY (deg)
ERROR (deg)
INL
25°C
125°C
1
1
H1
0.5
H2
11
10
9
-2
8
0
0
50
100
150
200
250
300
350
ANGLE (deg)
0
20
40
60
MAGNETIC FIELD (T)
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 (°C)
MA310 Rev. 1.0
9/22/2017
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
PIN FUNCTIONS
Package
Pin #
Name
1
2
V
A
3
4
5
6
Z
MOSI
CS
B
7
MISO
8
9
GND
W
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.
Motor commutation output.
10
11
12
13
14
15
16
TEST
MGL
SCLK
VDD
NC
U
MGH
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.
Motor commutation output.
Digital output indicating field strength above MGHT level.
MA310 Rev. 1.0
9/22/2017
Description
Motor commutation output.
Incremental output.
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
BLOCK DIAGRAM
VDD
MA310
NVM
CS
Registers
SCLK
MISO
Spinaxis front-end
BP
2D Hall effect
device
Phase
detection
Digital
conditioning
Amplitude
detection
Serial
interface
MOSI
A
ABZ
encoder
B
UVW
U
V
W
Z
MGL
MGH
GND
Figure 1: Functional Block Diagram
MA310 Rev. 1.0
9/22/2017
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MA310 – 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 directly digitizes the direction of
the
field
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 MA310 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 package top, 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.
MA310 Rev. 1.0
9/22/2017
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 MA310 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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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
Generally, the MagAlpha works fine 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 MA310 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
MA310 indicates multiple rotations for each
mechanical turn.
Serial Interface
The sensor supports the SPI serial interface for
angle reading and register programming.
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 PCB layout quality and
signal trace length. See Figure 7, Figure 8, 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 bits long. See the SPI Communication
section on page 13 for details.
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
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
MGL MGH
A
B
Z
MISO
VDD
MOSI
SCLK
1 mF
MA310
CPOL
CPHA
Data Order (DORD)
Mode 0
Mode 3
0
1
0
1
0 (MSB first)
CS
GND
U
V
TEST
Exposed pad
W
Figure 6: Connection for Supply Decoupling
MA310 Rev. 1.0
9/22/2017
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW 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.
MA310 Rev. 1.0
9/22/2017
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
SPI Communication
The sensor supports three types of SPI
operation:
Read angle
Read configuration register
Write configuration register
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).
CS falling edge
CS rising edge
LSB
MISO
Angle(15:4)
MOSI
0
If less resolution is needed, the angle can be
read by sending even fewer clock counts (since
MSB is first).
In case of fast reading, the MagAlpha keeps
sending the same data until the data is refreshed
(see the refresh rate in the General
Characteristics table on page 5).
See timing diagram in Figure 9 and Figure 10.
Table 4: Sensor Data Timing
Event
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.
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
Figure 9: Diagram of a Full 16-Bit SPI Angle
Reading
The MagAlpha family has sensors with different
features and levels of resolution. Check the data
output length 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
MA310 Rev. 1.0
9/22/2017
LSB
Angle(15:4)
0
0 0 0 0
Figure 10: Diagram of a Partial 8-Bit SPI Angle
Reading
SPI Read Register
A read register operation is constituted of two 16bit 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 8-bit register value
(MSB byte).
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
The first 16-bit SPI frame (read request) is:
MSB
MISO
MOSI
LSB
Angle(15:0)
command
reg. address
0 1 0 A4 A3 A2 A1 A0
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
0 0 0 0 0 0 0 0
MISO
The second 16-bit SPI frame (response) is:
reg. value
MISO V7 V6 V5 V4 V3 V2 V1 V0
MOSI
0 0 0 0 0 0 0 0
MSB
MOSI
LSB
0
See Figure 11 for a complete transmission
overview.
LSB
Angle(15:0)
command
0 1 0
reg. address
1 1 0 1 1
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
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
MA310 Rev. 1.0
9/22/2017
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
SPI Write Register
Table 5 shows the programmable 8-bit registers.
Data written to these registers are stored in the
on-chip non-volatile memory and reloaded
automatically during power on. The factory
default register values are shown in Table 6.
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 important 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 correctly written, 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
MA310 Rev. 1.0
9/22/2017
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
Figure 14: Example Write Output Rotation Direction (RD) to Counterclockwise (High), on Register 9, Bit 7
MA310 Rev. 1.0
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
REGISTER MAP
Table 5: Register Map
Bit 7
MSB
No
Hex
Bin
Bit 6
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
MGLT(2:0)
7
0x7
00111
NPP(2:0)
9
0x9
01001
RD
-
27
0x1B
11011
MGH
MGL
-
-
Bit 5
-
Bit 4
-
PPT(1:0)
-
Bit 3
Bit 2
Bit 1
Bit 0
LSB
-
ETY
ETX
-
-
-
-
ILIP(3:0)
-
PPT(7:2)
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
7
0x7
00111
0
0
0
0
0
0
0
0
9
0x9
01001
0
0
0
0
0
0
0
0
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
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
4
Parametrization of the ABZ index pulse.
Fig. 23
MGHT
3
Sets the field strength high threshold.
14
MGLT
3
Sets the field strength low threshold.
14
NPP
3
RD
1
Index length /
index position
Magnetic field high
threshold
Magnetic field low
threshold
Number of pole
pairs
Rotation direction
MA310 Rev. 1.0
9/22/2017
Description
See Table
Sets the zero position.
For side-shaft configuration: reduces 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.
8
UVW cycles per turn for motor
commutation.
Determines the sensor positive direction.
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11
12
12
15
16
10
18
MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW 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 8 shows the zero setting parameter.
Table 8: Zero Setting Parameter
Zero pos.
Z(15:0)
a0
(16 bit dec)
65536
65535
65534
…
2
1
0
1
2
…
65534
65535
Zero pos.
a0
(deg)
360.000
359.995
359.989
…
0.011
0.005
20 deg 16
2 61895
360 deg
Table 10: Rotation Direction Parameter
RD
Positive Direction
0
1
Clockwise (CW)
Counterclockwise (CCW)
BCT Settings (Bias Current Trimming)
Side-Shaft
When the MA310 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. We define the field ratio k with Equation (5):
k Brad / Btan
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
Figure 15: Positive Rotation Direction of the
Magnetic Field
(5)
Where Brad is the maximum radial magnetic field,
and Btan is the maximum tangential magnetic field
(see Figure 16).
(4)
In binary, it is written as 1111 0001 1100 0111.
Table 9 shows the content of the registers 0 and
1.
Table 9: Register 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 15 and
Table 10).
MA310 Rev. 1.0
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Figure 16: Side-Shaft Field
The ratio k depends on the magnet geometry
and 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 18).
E is the amplitude of this error.
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
The X-axis or the Y-axis bias current can be
reduced in order to recover an equal Hall signal
for all angles and suppress the error. The
parameter ETX and ETY controls in which
direction the 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
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 18). k can be calculated
with Equation (7):
k
tan(E a m )
tan(a m )
(7)
(6)
40
Equation (6) is plotted in Figure 17.
20
200
BCT
Error (deg)
150
0
-20
100
-40
50
0
0
1
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
Table 11: Example of BCT Settings
E (deg)
0
11.5
19.5
25.4
30.0
33.7
36.9
39.5
41.8
MA310 Rev. 1.0
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2E
m
Magnet Ratio k
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
BCT(7:0)
0
86
129
155
172
184
194
201
207
50
100
150
200
250
300
350
rotor angle (deg)
Figure 18: Error Curve in Side-Shaft
Configuration with BCT = 0
Some examples are given in Table 11.
Alternatively, the k parameter can be obtained
from the graph of Figure 19.
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
out of range, defined by the lower and upper
magnetic field thresholds, respectively MGLT
and MGHT (see Figure 21).
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 19: Relation between the Error Measured
with BCT = 0 and the Magnet Ratio k
Sensor Orientation
The dot marked on the package shows whether
the radial field is aligned with the sensor
coordinate X or Y (see Figure 20).
Figure 21: MGH and MGL Signals as a Function
of the Field Strength
MagHys, the typical hysteresis on the signals
MGH and MGL, is 6mT (see Figure 24). The
MGLT and MGHT thresholds are coded on three
bits and are stored in register 6 (see Table 13).
Table 13: 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 14).
Table 14: MGLT and MGHT Binary to mT Relation
Figure 20: Package Top View with X and Y Axes
MGLT or
MGHT (8)
Determine which axis needs to be reduced (see
the qualitative field distribution around a ring in
Figure 16). For instance, with the arrangement
depicted in Figure 20, the field along the sensor
Y direction is tangential and weaker. Therefore,
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).
000
001
010
011
100
101
110
111
Table 12: Trimming Direction Parameters
ETX
0
1
ETY
0
1
Enable Trimming of the X-Axis
Disabled
Enabled
Enable Trimming of the Y-Axis
Disabled
Enabled
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 the 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 can be read in
register 27 (bit 6, bit 7), and their logic state is
also given at the digital output pins 11 and 16.
Magnetic Field Thresholds
The magnetic flags (MGL and MGH) indicate
that the magnetic field at the sensor position is
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW 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 MA310 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 MA310 ABZ output emulates a 10-bit
incremental encoder (such as an optical
encoder) providing logic pulses in quadrature
(see Figure 22). 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 5).
The factory default value is 256. Table 15
describes how to program PPT(7:0) to set the
required resolution.
Figure 22: 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 bit ILIP(3:0) in register 0x5
(see Figure 23).
Table 15: 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 23: 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 and 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 prevent any
spurious transitions (see Figure 24).
For example, to set 120 pulses per revolution
(480 edges), set PPT to 120 - 1 = 119 (binary:
01110111). Registers 4 and 5 must be set as
shown below:
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 24: Hysteresis of the Incremental Output
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW 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 25).
Figure 26: UVW Output for 1 Pole Pair Rotor
during Rotation
Figure 25: ABZ Jitter
The measurable jitter is composed of a
systematic jitter (always the same deviation at a
given angle) and a random jitter.
The random jitter reflects the sensor noise, so
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.
The random jitter is a function of the rotation
speed. At lower speeds, the random jitter is
smaller than the sensor noise (see the Typical
Characteristic Curves on page 7).
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.
Block Commutation – UVW
The UVW output emulates the three Hall
switches usually used for the block commutation
of a 3-phase electric motor. The three logic
signals have a duty cycle of 50% and are shifted
by 60 degrees relative to each other (see Figure
26).
MA310 Rev. 1.0
9/22/2017
If the number of pole pairs of the motor exceeds
the number of pole pairs of the target magnet,
the MA310 is able to generate more than one
UVW cycle per revolution. It does this by dividing
the digital angle into the required number of
commutation steps per 360-degree revolution.
The parameter NPP(2:0) in register 0x7 sets the
number of pole pairs emulated, and the
corresponding commutation step angle for the
UVW signals. Table 16 describes the pole pair
configuration options.
Table 16: Number of UVW Pair Poles
NPP
(2:0)
000
001
010
011
100
101
110
111
Pole
pairs
1
2
3
4
5
6
7
8
States per
revolution
6
12
18
24
30
36
42
48
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State width
(deg)
60
30
20
15
12
10
8.6
7.5
23
MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
An example of the 30 degree UVW commutation
signal spacing for a 4-pole (2-pole pair) motor is
shown in Figure 27.
UVW Hysteresis
A hysteresis larger than the output noise is
introduced on the UVW output to avoid any
spurious transitions (see Figure 28).
Figure 27: UVW Commutation Signals for a 4Pole (2-Pole Pair) Motor
Figure 28: Hysteresis of the UVW Signal
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
TYPICAL APPLICATION CIRCUITS
Figure 29: Typical Configurations Using SPI Interface and MGH/MGL Signals
Figure 30: Typical Motor Configuration Using UVW Commutation Signals
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
PACKAGE INFORMATION
QFN-16 (3mmx3mm)
MA310 Rev. 1.0
9/22/2017
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MA310 – 12-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
APPENDIX A: DEFINITIONS
Effective Resolution (3σ
noise level)
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 sate 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
It can be obtained from the error curve
, where
is the average over 1,000 sensor outputs, and
is the
mechanical angle indicated by a high precision encoder (
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