MA704 [MPS]
10-Bit, Digital, Contactless Angle Sensor with ABZ Incremental & PWM Outputs;
| 型号： | MA704 |
| 厂家： | 
MONOLITHIC POWER SYSTEMS |
| 描述： | 10-Bit, Digital, Contactless Angle Sensor with ABZ Incremental & PWM Outputs |
| 文件： | 总27页 (文件大小：1098K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MagAlpha MA704
10-Bit, Digital, Contactless Angle Sensor
with ABZ Incremental & PWM Outputs
DESCRIPTION
FEATURES
The MA704 detects the absolute angular
position of a permanent magnet, typically a
diametrically magnetized cylinder on a rotating
shaft. The MA704 is particularly suited to track
highly dynamic movements with speeds up to
60’000 rpm.
10-Bit Resolution Absolute Angle Encoder
Contactless Sensing for Long Life
SPI Serial Interface for Digital Angle
Readout and Chip Configuration
Incremental 8-Bit ABZ Quadrature Encoder
Interface with Programmable Pulses Per
Turn from 1-64
The MA704 supports a wide range of magnetic
field strengths and spatial configurations. Both
end-of-shaft and off-axis (side-shaft mounting)
configurations are supported.
PWM Output 10-Bit
Programmable Magnetic Field Strength
Detection for Diagnostic Checks
3.3V, 12 mA Supply
-40°C to +125°C Operating Temperature
Available in a QFN-16 (3mmx3mm)
Package
The MA704 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.
APPLICATIONS
On-chip non-volatile memory provides storage
for configuration parameters, including the
reference zero angle position, ABZ encoder
settings, and magnetic field detection thresholds.
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
MA704 Rev. 1.0
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
ORDERING INFORMATION
Part Number*
Package
Top Marking
MA704GQ
QFN-16 (3mmx3mm)
See Below
* For Tape & Reel, add suffix –Z (e.g. MA704GQ–Z)
TOP MARKING
BAN: Product code of MA704GQ
Y: Year code
LLL: Lot number
PACKAGE REFERENCE
TOP VIEW
QFN-16 (3mmx3mm)
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
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
Thermal Resistance (3) θJA
QFN-16 (3mmx3mm) ............ 50.......12 ... °C/W
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-to-
ambient 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.
(2)
Continuous power dissipation (TA = +25°C)
..................................................................2.0W
Junction temperature...............................125°C
Lead temperature ....................................260°C
Storage temperature..................-65°C to 150°C
3) Measured on JESD51-7, 4-layer PCB.
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
ELECTRICAL CHARACTERISTICS
Parameter
Symbol Condition
Min
Typ
Max
Units
Recommended Operating Conditions
Supply voltage
VDD
IDD
Top
B
3.0
10.2
-40
30
3.3
3.6
13.8
125
V
Supply current
From -40°C to +125°C
11.7
mA
°C
Operating temperature
Applied magnetic field
60
mT
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MA704 – 10-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
Symbol Condition
Min
Typ
Max
Units
Absolute Output – Serial
Effective resolution
Noise RMS
3σ deviation of the noise distribution
9.5
0.04
850
12
10.0
0.06
980
10.5
0.08
1100
12
bit
deg
kHz
bit
Refresh rate
Data output length
Response Time
Power-up time (4)
Latency (4)
1.1
10
ms
µs
Constant speed propagation delay
8
Filter cutoff frequency (4)
Fcutoff
2970
Hz
Accuracy
At room temperature over the full
field range
INL at 25°C
0.7
1.1
deg
deg
INL between -40°C to
+125°C (5)
Over the full temperature range and
field range
Output Drift
Temperature induced drift
at room temperature (5)
0.015
0.04
deg/°C
From 25°C to 85°C
From 25°C to 125°C
0.5
1.0
1.2
2.1
deg
deg
Temperature induced
variation (5)
Magnetic field induced (5)
Voltage supply induced (5)
Absolute Output – PWM
PWM frequency
0.005
deg/mT
deg/V
0.3
782
9.5
920
16
1010
10.0
Hz
bit
PWM resolution
Incremental Output – ABZ
ABZ update rate
MHz
Resolution - edges per
turn
Programmable
4
1
256
64
Pulses per channel per
turn
PPT+1 Programmable
H
ABZ hysteresis (5)
Systematic jitter (5)
Random jitter (3σ)
Overall ABZ jitter (5)
1.1
6.0
3.0
0.5
deg
%
For PPT = 63, 0 - 100kRPM
For PPT = 63, 0 - 100kRPM
%
deg
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MA704 – 10-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
Min
Typ
Max
Units
Magnetic Field Detection Thresholds
Accuracy (5)
Hysteresis (5)
5
6
mT
mT
MagHys
Temperature drift (5)
-600
ppm/°C
Digital I/O
Input high voltage
Input low voltage
VIH
VIL
2.5
5.5
0.8
0.4
V
V
-0.3
Output low voltage (5)
Output high voltage (5)
Pull-down resistor
Rising edge slew rate(4)
Falling edge slew rate (4)
VOL
VOH
RPD
TR
IOL = 4mA
IOH = 4mA
V
2.4
43
V
55
0.7
0.7
97
kΩ
V/ns
V/ns
CL = 50pF
CL = 50pF
TF
NOTES:
4) Guaranteed by design.
5) Guaranteed by characteristic test.
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MA704 – 10-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
3
0
0.01
2.5
-3 dB
-5
2
-10
-15
-20
1.5
0.001
10
100
1000
f (Hz)
104
105
1
104
105
10
100
1000
104
105
0.1
1
10
100
1000
FREQUENCY (Hz)
ROTATION SPEED (rpm)
Non-Linearity (INL and
Error Curves at 50mT
Effective Resolution (3σ)
Harmonics)
1.5
11
2
10
9
INL
25°C
125°C
1
1
-45°C
0
8
H1
7
0.5
-1
-2
H2
6
5
0
0
20
40
60
80
100
120
0
50
100
150
200
250
300
350
0
20
40
60
80
100
MAGNETIC FIELD (mT)
ANGLE (deg)
MAGNETIC FIELD (T)
Current Consumption at
VDD = 3.3V
12
11.5
11
10.5
10
-50
0
50
100
150
TEMPERATURE (°C)
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
PIN FUNCTIONS
Package
Pin #
Name Description
1
2
3
4
5
6
SSD
A
Data out (SSI).
Incremental output.
Z
Incremental output.
MOSI
CS
B
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.
7
MISO
8
GND
PWM
TEST
MGL
SCLK
VDD
NC
Supply ground.
9
PWM output.
10
11
12
13
14
15
16
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.
SSCK Clock (SSI). SSCK has an internal pull-down resistor.
MGH
Digital output indicating field strength above MGHT level.
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
BLOCK DIAGRAM
VDD
MA704
CS
NVM
Registers
SCLK
MISO
Spinaxis front-end
MOSI
Serial
interface
Digital
conditioning
Phase
detection
SSCK
SSD
BP
2D Hall effect
device
A
B
Z
Amplitude
detection
ABZ
encoder
PWM
PWM
MGL
MGH
GND
Figure 1: Functional Block Diagram
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
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.
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 Spinaxis
method, which digitizes the direction of the field
directly without complex arctangent computation
or feedback loop-based circuits (interpolators).
TM
TM
The Spinaxis method is based on phase
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.
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.
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.
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 MA704 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 MA704 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.
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):
1 2s
(1s)2
H(s)
(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.
Sensor – Magnet Mounting
The sensitive volume of the MA704 is confined
in a region less than 100µm wide and has
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MA704 – 10-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.
Serial Interface
The sensor supports the SPI serial interface for
Figure 4: End-of-Shaft Mounting
angle reading and register programming.
Alternatively, the SSI bus can be used for angle
reading (programming through SSI is not
supported).
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 MA704 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
MA704 indicates multiple rotations for each
mechanical turn.
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.
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).
Table 1: SPI Specification
Mode 0
Low
Mode 3
High
SCLK idle state
Data capture
On SCLK rising edge
On SCLK falling edge
High
3.3 V
Data transmission
CS idle state
MGL MGH
VDD
A
B
Z
Data order
MSB first
MISO
MOSI
SCLK
CS
Table 2: SPI Standard
Mode 0
Mode 3
1 mF
CPOL
CPHA
0
1
1
MA704
GND
0
SSCK
Data Order (DORD)
0 (MSB first)
SSD
Exposed pad
TEST
PWM
Figure 6: Connection for Supply Decoupling
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
tidleAngle
tidleReg
tnvm
tcsL
tsclk
tcsH
tsclkL tsclkH
CS
SCLK
MISO
MOSI
tMISO
hi-Z
tMISO
tMISO
MSB
LSB
hi-Z
MSB
X
MSB
LSB
X
MSB
tMOSI
Figure 7: SPI Timing Diagram
tidleAngle
tidleAngle
tidleAngle
tidleReg
tidleReg
tidleAngle
tnvm
tidleReg
CS
Angle
Angle
Angle
Angle
Reg Value
0
Angle
Angle
Reg Value
0
Angle
0
MISO
MOSI
0
0
0
Read Reg Cmd
0
Write Reg Cmd
Figure 8: Minimum Idle Time
Table 3: SPI Timing
Description
Parameter (6)
tidleAngle
Min
Max
Unit
ns
Idle time between two subsequent angle transmissions
Idle time before and after a register readout
150
750
tidleReg
ns
Idle time between a write command and a register readout
(delay necessary for non-volatile memory update)
tnvm
20
ms
tcsL
tsclk
Time between CS falling edge and SCLK falling edge
SCLK period
80
40
20
20
25
ns
ns
ns
ns
ns
ns
ns
tsclkL
tsclkH
tcsH
Low level of SCLK signal
High level of SCLK signal
Time between SCLK rising edge and CS rising edge
SCLK setting edge to data output valid
Data input valid to SCLK reading edge
tMISO
tMOSI
15
15
NOTE:
6) All values are guaranteed by design.
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
SPI Communication
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.
The sensor supports three types of SPI
operation:
Read angle
Read configuration register
Write configuration register
MSB
LSB
MISO
MOSI
Angle(15:4)
0
Each operation has a specific frame structure
described below.
SPI Read Angle
If less resolution is needed, the angle can be
read by sending even fewer clock counts (since
the MSB is first).
Every 1µs, new data is transferred into the output
buffer. The master device triggers the reading by
pulling CS low.
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.
When a trigger event is detected, the data
remains in the output buffer until the CS signal is
de-asserted (see Table 4).
Table 4: Sensor Data Timing
Event
Action
Start reading and freeze
output buffer
Release of the output buffer
CS falling edge
CS rising edge
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
Figure 9: Diagram of a Full 16-Bit SPI Angle
Reading
MISO
MOSI
Angle(15:0)
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:
Figure 10: Diagram of a Partial 8-Bit SPI Angle
Reading
MSB
LSB
MISO
MOSI
Angle(15:4)
0
0 0 0 0
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
SPI Read Register
See Figure 11 for a complete transmission
overview.
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 zero. The
second frame returns the 8-bit register value
(MSB byte).
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
LSB
MISO
Angle(15:0)
reg. address
First 16-bit SPI frame (read request):
command
MSB
LSB
MOSI
0
1
0
1
1
0
1
1
0 0 0 0 0 0 0 0
MISO
Angle(15:0)
In the second frame, the MagAlpha replies:
command
reg. address
A4 A3 A2 A1 A0 0 0 0 0 0 0 0 0
reg. value
MOSI
0
1
0
MISO MGH MGL X X X X X X
0
0
0
0
0
0
0
0
Second 16-bit SPI frame (response):
MSB
LSB
reg. value
MOSI
0
MISO V7 V6 V5 V4 V3 V2 V1 V0
0
0
0
0
0
0
0
0
See Figure 12 for a complete example overview.
MSB
LSB
MOSI
0
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
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
SPI Write Register
Second 16-bit SPI frame (response):
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.
reg. value
MISO V7 V6 V5 V4 V3 V2 V1 V0
0
0
0
0
0
0
0
0
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.
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).
For example, to set the value of the output
rotation direction (RD) to counterclockwise
(high). Write register 9 by sending the following
first frame:
The on-chip memory is guaranteed to endure
1,000 write cycles at 25°C.
MSB
LSB
MISO
Angle(15:0)
reg. address
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.
command
reg. value
1 0 0 0 0 0 0 0
MOSI
1
0
0
0 1 0 0 1
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
0
0
0
0
0
0
0
0
MSB
LSB
First 16-bit SPI frame (write request):
MOSI
0
MSB
LSB
MISO
MOSI
Angle(15:0)
See Figure 14 for a complete example.
command
reg. address
reg. value
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
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
Figure 14: Example Write Output Rotation Direction (RD) to Counterclockwise (High), on Register 9, Bit 7
SSI
SSI Communication
SSI is a two-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.
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
Description
Parameter
Min
Max
15
16
8
Unit
ns
tssd
tssck
tssckL
tssckH
tm
SSCK period
Low level of SSCK signal
0.04
0.02
0.02
25
µs
µs
High level of SSCK signal
8
µs
Transfer timeout (monoflop time)
Dead time: SSCK high time for next data reading
µs
tp
40
µs
SSI Read Angle
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.
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).
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
The first data MSB is transmitted on the second
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).
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.
Table 6: Sensor Data Timing
Release of the Output Buffer
Trigger Event
First SSCK pulse rising
SSCK falling edge + time out tm (Fig 15)
edge
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
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
REGISTER MAP
Table 7: Register Map
Bit 7
MSB
Bit 0
LSB
No
Hex
Bin
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
0
1
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x9
0x1B
00000
00001
00010
00011
00100
00101
00110
01001
11011
Z(7:0)
Z(15:8)
2
BCT(7:0)
3
-
-
-
-
-
-
-
-
ETY
-
ETX
-
4
PPT(1:0)
ILIP(3:0)
5
-
-
MGLT(2:0)
-
PPT(5:2)
6
MGHT(2:0)
-
-
-
-
-
-
9
RD
-
-
-
-
-
-
-
-
27
MGH
MGL
Table 8: Factory Default Values
Bit 7
MSB
Bit 0
LSB
No
Hex
Bin
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
0
1
2
3
4
5
6
9
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x9
00000
00001
00010
00011
00100
00101
00110
01001
0
0
0
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
1
1
0
0
0
0
0
0
1
1
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
0
Table 9: Programming Parameters
Number of
Parameters
Symbol
Description
See Table
Bits
Zero Setting
Z
16
Set the zero position
10
13
Bias Current
Trimming
For side-shaft configuration: reduce the
bias current of the X or Y Hall device
BCT
8
1
1
6
4
3
Biased current trimmed in the X direction
Hall device
Enable Trimming X
Enable Trimming Y
Pulses Per Turn
ETX
ETY
14
14
Biased current trimmed in the Y direction
Hall device
Number of pulses per turn of the ABZ
output
PPT
17
Index Length /
Index Position
ILIP
Parametrization of the ABZ index pulse
Sets the field strength high threshold
Fig 26
16
Magnetic Field
High Threshold
MGHT
Magnetic Field
Low Threshold
MGLT
RD
3
1
Sets the field strength low threshold
16
12
Rotation Direction
Determines the sensor positive direction
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MA704 – 10-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.
Figure 18: Positive Rotation Direction of the
Magnetic Field
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):
Table 12: Rotation Direction Parameter
RD
0
Positive Direction
Clockwise (CW)
a0 216 Z(15 : 0)
(3)
1
Counterclockwise (CCW)
BCT Settings (Bias Current Trimming)
Table 10 shows the zero setting parameter.
Side Shaft
Table 10: Zero Setting Parameter
When the MA704 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):
Zero pos.
a0 (16-bit dec)
Zero pos.
a0 (deg)
360.000
359.995
359.989
…
Z(15:0)
0
1
2
65536
65535
65534
…
…
65534
65535
2
1
0.011
0.005
k Brad / Btan
(5)
Where Brad and Btan are the maximum radial and
Example
tangential magnetic fields (see Figure 19).
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):
20deg
Z(15: 0) 216
216 61895
(4)
360deg
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
Figure 19: Side-Shaft Field
Reg
0
1
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
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 21).
E is the amplitude of this error.
1
1
1
1
0
1
0
1
0
0
1
0
1
0
1
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).
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW 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.
E (deg)
Magnet Ratio k
BCT(7:0)
0
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0
11.5
19.5
25.4
30.0
33.7
36.9
39.5
41.8
86
129
155
172
184
194
201
207
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):
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
1
BCT(7:0) 258 1
(6)
k
The graph in Figure 20 shows the optimum BCT
value for a particular k ratio.
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):
200
150
100
50
tan(E am )
k
(7)
tan(am )
40
20
0
0
1
1.5
2
2.5
3
k
3.5
4
4.5
5
m
2E
Figure 20: Relation between the k Ratio and the
Optimum BCT to Recover Linearity
Table 13 shows some typical BCT values.
-20
-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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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
Magnetic Field Thresholds
5
4.5
4
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).
3.5
3
2.5
2
1.5
1
0
5
10
15
20
25
30
35
40
E (deg)
Figure 24: MGH and MGL Signals as a Function
of the Field Strength
Figure 22: Relation between the Error Measured
with BCT = 0 and the Magnet Ratio k
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).
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).
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).
Table 16: MGLT and MGHT: Binary to mT
Relation
Figure 23: Package Top View with X and Y Axes
Field threshold in mT (7)
MGLT or
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).
MGHT (8)
From low to high From high to low
magnetic field
magnetic field
000
001
010
011
100
101
110
111
26
41
56
70
84
98
112
126
20
35
50
64
78
92
106
120
Table 14: Trimming Direction Parameters
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.
ETX
0
Enable Trimming of the X-Axis
Disabled
Enabled
Enable Trimming of the Y-Axis
Disabled
1
ETY
0
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.
1
Enabled
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MA704 – 10-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
reg. address MSB
value
LSB
0
1
0
1 1 0 1 1 0 0 0 0 0 0 0 0
The MA704 answers with the register 27 content
in the next transmission:
R[7:0]
MGH MGL
x
x
x
x
x
x
ABZ Incremental Encoder Output
The MA704 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 eight 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 Edges per
PPT(7:0)
Figure 26: ILIP Parameter Effect on Index Shape
Turn
1
Turn
4
00000000
00000001
00000010
00000011
…
MIN
…
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.
2
3
4
…
8
12
16
…
ABZ Hysteresis
11111100
11111101
11111110
11111111
253
254
255
256
1012
1016
1020
1024
A hysteresis larger than the output noise is
introduced on the ABZ output to avoid any
spurious transitions (see Figure 27).
MAX
For example, to set 120 pulses per revolution
(i.e. 480 edges), set PPT to 120 - 1 = 119. In
binary: 01110111. Registers 4 and 5 must be set
as shown in Table 18.
Table 18: Example PPT setting for 120 pulses
B7 B6 B5 B4 B3 B2 B1 B0
R4
R5
1
0
1
0
0
0
0
1
0
1
0
1
0
0
0
1
Figure 27: Hysteresis of the Incremental Output
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
ABZ Jitter
The angle can be calculated with Equation (8):
The ABZ state is updated at a frequency of
16MHz, enabling accurate operation up to a very
high rpm (above 105 rpm).
tON
1
angle(in deg) 360
34
1 (8)
32
tON tOFF
The jitter characterizes how far a particular ABZ
edge can occur at an angular position different
from the ideal position (see Figure 28).
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.
Top Signal: 0°
Bottom Signal: Full Scale (i.e.: 360°(1-1/4096))
Figure 29: PWM Output Timing
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 (1/34
of the period) and a maximum value (33/34 of the
period) (see Figure 29), so the duty cycle varies
from 1/34 to 33/24 with a resolution of 10 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)).
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
TYPICAL APPLICATION CIRCUITS
Figure 30: Typical Configurations Using SPI Interface and MGH/MGL Signals
Figure 31: Typical Configuration Using ABZ Interface
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
PACKAGE INFORMATION
QFN-16 (3mmx3mm)
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
APPENDIX A: DEFINITIONS
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).
Effective Resolution (3σ
noise level)
Rate at which new data points are stored in the output buffer.
Refresh Rate
Rate at which a new ABZ state is computed. The inverse of this rate is
the minimum time between two ABZ edges.
ABZ Update Rate
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
Latency
is
, where 푣 is the angular velocity in deg/s.
Time until the sensor delivers valid data starting at power up.
Power-Up Time
Maximum deviation between the average sensor output (at a fixed
position) and the true mechanical angle.
400
350
300
lag
250
ideal
sensor output
200
150
100
50
INL
300
sensor out
best straight fit
Integral
(INL)
Non-Linearity
resolution
( ± 3 )
0
0
100
200
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 (<0.001 deg). INL is then
computed with Equation (A1):
max(err(a)) min(err(a))
INL
(A1)
2
Angle variation rate when one parameter is changed (e.g.: temperature,
VDD) and all the others, including the shaft angle, are maintained
constant.
Drift
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MA704 – 10-BIT, DIGITAL ANGLE SENSOR WITH ABZ & UVW OUTPUTS
APPENDIX B: SPI COMMUNICATION CHEATSHEET
Read Angle
Read Register
Write Register
NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third
party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not assume
any legal responsibility for any said applications.
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