AS5245_1 [AMSCO]
Programmable 360º Magnetic Angle Encoder with Absolute SSI and PWM Output; 可编程360º磁性角度编码器与绝对SSI和PWM输出
| 型号： | AS5245_1 |
| 厂家： | 
AMS(艾迈斯) |
| 描述： | Programmable 360º Magnetic Angle Encoder with Absolute SSI and PWM Output |
| 文件： | 总31页 (文件大小：877K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Data Sheet
AS5245
Programmable 360º Magnetic Angle Encoder with Absolute SSI and
PWM Output
ꢀ
ꢀ
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Two digital 12-bit absolute outputs
1 General Description
The AS5245 is a contactless magnetic angle encoder for accurate
measurement up to 360º and includes two AS5145 devices in a
punched stacked leadframe.
Quadrature A/B (10- or 12-bit) and Index output signal
User programmable zero position
Failure detection mode for magnet placement monitoring and
loss of power supply
It is a system-on-chip, combining integrated Hall elements, analog
front end and digital signal processing in a single device.
ꢀ
“Red-Yellow-Green” indicators display placement of magnet in
Z-axis
To measure the angle, only a simple two-pole magnet, rotating over
the center of the chip is required. The magnet may be placed above
or below the IC.
ꢀ
ꢀ
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Tolerant to magnet misalignment and air gap variations
Wide temperature range: - 40ºC to +150ºC
Unique Chip Identifier
The absolute angle measurement provides instant indication of the
magnet’s angular position with a resolution of 0.0879º = 4096
positions per revolution. This digital data is available as a serial bit
stream and as a PWM signal.
Fully automotive qualified to AEC-Q100, grade 0
Small package: QFN 32 LD (7x7)
An internal voltage regulator allows operation of the AS5245 from
3.3V or 5.0V supplies.
3 Applications
The AS5245 is fully automotive qualified to AEC-Q100, grade 0.
The AS5245 is ideal for applications with an angular travel range
from a few degrees up to a full turn of 360º. The device is suitable for
Automotive applications like Throttle position sensors, Gas/brake
pedal position sensing, Headlight position control, Contactless rotary
position sensing, Front panel rotary switches and Replacement of
potentiometer.
2 Key Features
ꢀ
Contactless high resolution rotational position encoding over a
full turn of 360º
Figure 1. AS5245 Block Diagram
VDD3V3
MagINCn
MagDECn
VDD5V
LDO 3.3V
PWM
PWM
Interface
Sin
Ang
DO
DSP
Absolute
Interface
(SSI)
Cos
Mag
Hall Array
&
CSn
Frontend
Amplifier
CLK
OTP
Register
PDIO
DTEST1_A
DTEST2_B
Incremental
Interface
Mux
AS5245
Mode_Index
Note: This Block Diagram presents only one die
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AS5245
Data Sheet - Contents
Contents
1 General Description ..................................................................................................................................................................
2 Key Features.............................................................................................................................................................................
3 Applications...............................................................................................................................................................................
4 Pin Assignments .......................................................................................................................................................................
4.1 Pin Descriptions....................................................................................................................................................................................
5 Absolute Maximum Ratings ......................................................................................................................................................
6 Electrical Characteristics...........................................................................................................................................................
6.1 System Specifications ..........................................................................................................................................................................
7 Timing Characteristics ..............................................................................................................................................................
1
1
1
3
4
5
6
7
9
8 Detailed Description................................................................................................................................................................ 10
8.1 Mode_Index Pin.................................................................................................................................................................................. 10
8.2 Synchronous Serial Interface (SSI) .................................................................................................................................................... 11
8.2.1 Serial Data Contents.................................................................................................................................................................. 11
8.2.2 Z-axis Range Indication (Push Button Feature, Red/Yellow/Green Indicator)........................................................................... 12
8.2.3 Incremental Mode...................................................................................................................................................................... 12
8.2.4 Sync Mode................................................................................................................................................................................. 14
8.2.5 Sine/Cosine Mode ..................................................................................................................................................................... 14
8.2.6 Daisy Chain Mode ..................................................................................................................................................................... 14
8.3 Pulse Width Modulation (PWM) Output.............................................................................................................................................. 15
8.3.1 Changing the PWM Frequency.................................................................................................................................................. 16
8.4 Analog Output..................................................................................................................................................................................... 16
9 Application Information ........................................................................................................................................................... 17
9.1 Programming the AS5245 .................................................................................................................................................................. 17
9.1.1 Zero Position Programming....................................................................................................................................................... 17
9.1.2 OTP Memory Assignment.......................................................................................................................................................... 18
9.1.3 User Selectable Settings ........................................................................................................................................................... 18
9.1.4 OTP Default Setting................................................................................................................................................................... 19
9.1.5 Redundancy............................................................................................................................................................................... 19
9.1.6 Redundant Programming Option............................................................................................................................................... 19
9.2 Alignment Mode.................................................................................................................................................................................. 20
9.3 3.3V / 5V Operation............................................................................................................................................................................ 21
9.4 Choosing the Proper Magnet.............................................................................................................................................................. 22
9.5 Failure Diagnostics............................................................................................................................................................................. 23
9.5.1 Magnetic Field Strength Diagnosis............................................................................................................................................ 23
9.5.2 Power Supply Failure Detection ................................................................................................................................................ 23
9.6 Angular Output Tolerances................................................................................................................................................................. 23
9.6.1 Accuracy.................................................................................................................................................................................... 23
9.6.2 Transition Noise......................................................................................................................................................................... 25
9.6.3 High Speed Operation ............................................................................................................................................................... 25
9.6.4 Propagation Delays ................................................................................................................................................................... 26
9.6.5 Internal Timing Tolerance.......................................................................................................................................................... 26
9.6.6 Temperature .............................................................................................................................................................................. 26
9.6.7 Accuracy over Temperature ...................................................................................................................................................... 26
9.7 AS5245 Differences to AS5045.......................................................................................................................................................... 27
10 Package Drawings and Markings ......................................................................................................................................... 28
11 Ordering Information ............................................................................................................................................................. 30
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AS5245
Data Sheet - Pin Assignments
4 Pin Assignments
Figure 2. Pin Assignments (Top View)
32 31 30 29 28 27 26 25
1
2
3
4
5
6
7
8
DTest1_A_Bottom
DTest2_B_Top
DTest2_B_Bottom
NC
24
23
22
21
20
19
18
17
VDD3V_Bottom
NC
NC
NC
AS5245
NC
NC
Mode_Index_Top
Mode_Index_Bottom
VSS_Top
PWM_Top
PWM_Bottom
CSn_Top
9
10 11 12 13 14 15 16
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AS5245
Data Sheet - Pin Assignments
4.1 Pin Descriptions
Table 1. Pin Descriptions
Pin Name
DTest1_A
DTest2_B
NC
Pin Number
Pin Type
Digital output
Digital output
-
Description
Test output in default mode
Test output in default mode
1, 32
2, 3
For internal use. Must be left unconnected
4, 5
Select between slow (open, low: VSS) and fast (high) mode. Internal pull-
down resistor. Hard wired connection to VDD or GND recommended.
Mode_Index
VSS
6, 7
8, 9
Digital I/O pull-down
Supply pin
Negative Supply Voltage (GND)
OTP Programming Input and Data Input for Daisy Chain mode.
Internal pull-down resistor (74kΩ). Should be connected to VSS if
programming is not used.
PDIO
10, 11
Digital input pull-down
Digital input, Schmitt-
trigger input
Clock Input of Synchronous Serial Interface; Schmitt-Trigger input
Data Output of Synchronous Serial Interface
CLK
DO
12, 13
14, 15
16, 17
Digital output / tri-
state
Chip Select. Active low. Schmitt-Trigger input, internal pull-up resistor
(50kΩ)
Digital input pull-up,
Schmitt-trigger input
CSn
Pulse Width Modulation
PWM
NC
18, 19
20, 21
22, 23
Digital output
For internal use. Must be left unconnected
For internal use. Must be left unconnected
-
-
NC
3V-Regulator Output for internal core, regulated from VDD5V. Connect to
VDD5V for 3V supply voltage. Do not load externally.
VDD3V3
VDD5V
24, 25
26, 27
28, 29
Supply pin
Supply pin
Positive Supply Voltage, 3.0V to 5.5V
Magnet Field Magnitude Increase. Active low. Indicates a distance
reduction between the magnet and the device surface.
Digital output open
drain
MagINCn
Magnet Field Magnitude Decrease. Active low. Indicates a distance
increase between the device and the magnet.
Digital output open
drain
MagDECn
30, 31
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AS5245
Data Sheet - Absolute Maximum Ratings
5 Absolute Maximum Ratings
Stresses beyond those listed in Table 2 may cause permanent damage to the device. These are stress ratings only, and functional operation of
the device at these or any other conditions beyond those indicated in Electrical Characteristics on page 6 is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
Table 2. Absolute Maximum Ratings
Parameter
Min
-0.3
-0.3
-0.3
-100
Max
7
Units
V
Comments
DC supply voltage at pin VDD5V
DC supply voltage at pin VDD3V3
Input pin voltage
5
V
7
V
Pins Prog, MagINCn, MagDECn, CLK, CSn
Norm: EIA/JESD78 Class II Level A
Norm: JESD22-A114E
Input current (latchup immunity)
Electrostatic discharge
100
±2
+150
mA
kV
ºC
Storage temperature
-55
t=20 to 40s, Norm: IPC/JEDEC J-Std-020C
Lead finish 100% Sn “matte tin”
Body temperature (Lead-free package)
260
ºC
Humidity non-condensing
Ambient temperature
5
85
%
-40
150
ºC
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AS5245
Data Sheet - Electrical Characteristics
6 Electrical Characteristics
TAMB = -40 to +150ºC, VDD5V = 3.0-3.6V (3V operation) VDD5V = 4.5-5.5V (5V operation) unless otherwise noted.
Table 3. Electrical Characteristics
Symbol
Operating Conditions
TAMB
Parameter
Condition
Min
Typ
Max
Unit
Ambient temperature
Supply current
-40
+150
21
ºC
Isupp
(one die only)
16
mA
VDD5V
Supply voltage at pin VDD5V
4.5
3.0
5.0
5.5
5V Operation
V
V
Voltage regulator output voltage at pin
VDD3V3
3.3
3.6
VDD3V3
VDD5V
Supply voltage at pin VDD5V
Supply voltage at pin VDD3V3
3.0
3.0
3.3
3.3
3.6
3.6
3.3V Operation
(pin VDD5V and VDD3V3 connected)
VDD3V3
Power-on reset thresholds
VON
1.37
1.08
2.2
1.9
2.9
2.6
On voltage; 300mV typ. hysteresis
V
VDD
DC supply voltage 3.3V (
3V3)
Power-on reset thresholds
Off voltage; 300mV typ. hysteresis
VOFF
Programming Conditions
VPROG
Programming voltage
Programming voltage off level
Programming current
Voltage applied during programming
Line must be discharged to this level
Current during programming
3.3
0
3.6
1
V
V
VProgOff
IPROG
100
∞
mA
Ω
Rprogrammed
Programmed fuse resistance (log 1)
10µA maximum current@100mV
100k
50
Unprogrammed fuse resistance (log
0)
Runprogrammed
2mA maximum current@100mV
100
Ω
DC Characteristics CMOS Schmitt-Trigger Inputs: CLK, CSn (CSn = Internal Pull-up)
0.7 *
VIH
VIL
High level input voltage
Low level input voltage
Normal operation
V
VDD5V
0.3 *
V
V
VDD5V
VIon- VIoff
ILEAK
IiL
Schmitt Trigger hysteresis
Input leakage current
1
CLK only
-1
1
µA
Pull-up low level input current
CSn only, VDD5V: 5.0V
-30
-100
DC Characteristics CMOS / Program Input: PDIO
0.7 *
VDD5V
V
V
VIH
High level input voltage
High level input voltage
VDD5V
During programming,
Either with 3.3V or 5V supply
VPROG
3.3
3.6
0.3 *
V
VIL
Low level input voltage
High level input current
VDD5V
IiL
VDD5V: 5.5V
30
100
µA
DC Characteristics CMOS Output Open Drain: MagINCn, MagDECn
IOZ
Open drain leakage current
Low level output voltage
1
µA
V
VSS
+0.4
VOL
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AS5245
Data Sheet - Electrical Characteristics
Table 3. Electrical Characteristics
Symbol
Parameter
Output current
Condition
VDD5V: 4.5V
VDD5V: 3V
Min
Typ
Max
4
Unit
IO
mA
2
DC Characteristics CMOS Output: PWM
VDD5V–
0.5
VOH
High level output voltage
V
V
VSS
VOL
Low level output voltage
Output current
+0.4
VDD5V: 4.5V
VDD5V: 3V
4
2
IO
mA
DC Characteristics CMOS Output: A, B, Index
VDD5V–
0.5
VOH
High level output voltage
Low level output voltage
V
V
VSS
+0.4
VOL
VDD5V: 4.5V
VDD5V: 3V
4
2
IO
Output current
mA
DC Characteristics Tri-state CMOS Output: DO
VDD5V–
0.5
VOH
High level output voltage
Low level output voltage
V
V
VSS
+0.4
VOL
VDD5V: 4.5V
VDD5V: 3V
4
2
1
IO
Output current
mA
µA
IOZ
Tri-state leakage current
6.1 System Specifications
TAMB = -40 to +150ºC, VDD5V = 3.0 to 3.6V (3V operation) VDD5V = 4.5 to 5.5V (5V operation) unless otherwise noted.
Table 4. Input Specification
Symbol
Parameter
Condition
Min
Typ
Max
Unit
RES
Resolution
0.088 deg
12
bit
Maximum error with respect to the best line fit.
Centered magnet without calibration, TAMB
=25ºC.
INLopt
Integral non-linearity (optimum)
Integral non-linearity (optimum)
±0.5
±0.9
deg
deg
Maximum error with respect to the best line fit.
Centered magnet without calibration,
INLtemp
º
TAMB = -40 to +150 C
Best line fit = (Errmax – Errmin) / 2
Over displacement tolerance with 6mm
diameter magnet, without calibration,
TAMB = -40 to +150ºC
INL
DNL
TN
Integral non-linearity
Differential non-linearity
Transition noise
±1.4
deg
deg
12bit, no missing codes
±0.044
0.06
1 sigma, fast mode (MODE = 1)
Deg
RMS
1 sigma, slow mode
(MODE = 0 or open)
0.03
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AS5245
Data Sheet - Electrical Characteristics
Table 4. Input Specification
Symbol
Parameter
Condition
Min
Typ
Max
Unit
Fast mode (Mode = 1);
Until status bit OCF = 1
20
tPwrUp
Power-up time
ms
Slow mode (Mode = 0 or open);
Until OCF = 1
80
System propagation delay
absolute output : delay of ADC, DSP
and absolute interface
Fast mode (MODE = 1)
96
tdelay
µs
Slow mode (MODE = 0 or open)
384
TAMB
º
= 25 C, slow mode
(MODE=0 or open)
2.48
2.35
9.90
9.38
2.61
2.61
2.74
2.87
10.94
11.46
1
Internal sampling rate for absolute
output:
fS
kHz
TAMB
º
= -40 to +150 C, slow mode (MODE=0
or open)
TAMB
º
= 25 C, fast mode
10.42
10.42
(MODE = 1)
Internal sampling rate for absolute
output
fS
kHz
TAMB
º
= -40 to +150 C, fast mode
(MODE=1)
Maximum clock frequency to read out serial
data
CLK/SEL
Read-out frequency
MHz
Figure 3. Integral and Differential Non-Linearity Example
10bit code
α
1023
1023
Actual curve
Ideal curve
TN
2
1
DNL+1LSB
INL
0.35°
0
512
512
0
°
360
180°
[degrees]
°
α
0
Integral Non-Linearity (INL) is the maximum deviation between actual position and indicated position.
Differential Non-Linearity (DNL) is the maximum deviation of the step length from one position to the next.
Transition Noise (TN) is the repeatability of an indicated position.
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AS5245
Data Sheet - Timing Characteristics
7 Timing Characteristics
TAMB= -40 to +150ºC, VDD5V= 3.0 to 3.6V (3V operation) VDD5V= 4.5 to 5.5V (5V operation), unless otherwise noted.
Table 5. Timing Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Units
Synchronous Serial Interface (SSI)
Time between falling edge of CSn and
data output activated
tDOactive
tCLKFE
Data output activated (logic high)
First data shifted to output register
Start of data output
100
ns
ns
ns
ns
ns
Time between falling edge of CSn and
first falling edge of CLK
500
500
Rising edge of CLK shifts out one bit at a
time
TCLK/2
Time between rising edge of CLK and
data output valid
tDOvalid
tDOtristate
tCSn
fCLK
Data output valid
413
100
After the last bit DO changes back to “tri-
state”
Data output tri-state
CSn =high; To initiate read-out of next
angular position
Pulse width of CSn
Read-out frequency
500
>0
ns
Clock frequency to read out serial data
1
MHz
Pulse Width Modulation Output
Signal period = 4098µs ±10% at TAMB
fPWM
PWM frequency
220
244
268
Hz
= -40 to +150ºC
PWMIN
Minimum pulse width
Maximum pulse width
Position 0d; angle 0 degree
0.90
1
1.10
µs
µs
PWMAX
Position 4098d; angle 359.91 degrees
3686
4096
4506
Programming Conditions
tPROG
tCHARGE
fLOAD
Programming time per bit
Refresh time per bit
LOAD frequency
Time to prog. a singe fuse bit
Time to charge the cap after tPROG
Data can be loaded at n x 2µs
Read the data from the latch
Write the data to the latch
10
1
20
µs
µs
500
2.5
2.5
kHz
MHz
MHz
fREAD
READ frequency
fWRITE
WRITE frequency
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AS5245
Data Sheet - Detailed Description
8 Detailed Description
The AS5245 is manufactured in a CMOS standard process and uses a spinning current Hall technology for sensing the magnetic field
distribution across the surface of the chip. The integrated Hall elements are placed around the center of the device and deliver a voltage
representation of the magnetic field at the surface of the IC.
Through Sigma-Delta Analog / Digital Conversion and Digital Signal-Processing (DSP) algorithms, the AS5245 provides accurate high-resolution
absolute angular position information. For this purpose, a Coordinate Rotation Digital Computer (CORDIC) calculates the angle and the
magnitude of the Hall array signals. The DSP is also used to provide digital information at the outputs MagINCn and MagDECn that indicate
movements of the used magnet towards or away from the device’s surface. A small low cost diametrically magnetized (two-pole) standard
magnet provides the angular position information (see Figure 16).
The AS5245 senses the orientation of the magnetic field and calculates a 12-bit binary code. This code can be accessed via. a Synchronous
Serial Interface (SSI). In addition, an absolute angular representation is given by a Pulse Width Modulated signal at pin 12 (PWM). This PWM
signal output also allows the generation of a direct proportional analog voltage, by using an external Low-Pass-Filter. The AS5245 is tolerant to
magnet misalignment and magnetic stray fields due to differential measurement technique and Hall sensor conditioning circuitry.
Figure 4. Typical Arrangement of AS5245 and Magnet
8.1 Mode_Index Pin
The Mode_Index pin activates or deactivates an internal filter that is used to reduce the analog output noise. Activating the filter (Mode pin =
LOW or open) provides a reduced output noise of 0.03º rms. At the same time, the output delay is increased to 384µs. This mode is
recommended for high precision, low speed applications.
Deactivating the filter (Mode pin = HIGH) reduces the output delay to 96µs and provides an output noise of 0.06º rms. This mode is
recommended for higher speed applications.
Setting up the Mode pin affects the following parameters:
Table 6. Slow and Fast Mode Parameters
Parameter
Slow Mode (mode=low or open)
Fast Mode (mode=high, VDD=5V)
Sampling rate
2.61 kHz (384 µs)
≤ 0.03º rms
384µs
10.42 kHz (96µs)
≤ 0.06º rms
96µs
Transition noise (1 sigma)
Output delay
Maximum speed @ 4096 samples/rev
Maximum speed @ 1024 samples/rev
Maximum speed @ 256 samples/rev
Maximum speed @ 64 samples/rev
38 rpm
153 rpm
153 rpm
610 rpm
610 rpm
2441 rpm
9766 rpm
2441 rpm
Note: A change of the Mode during operation is not allowed. The setup must be constant during power up and during operation.
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AS5245
Data Sheet - Detailed Description
8.2 Synchronous Serial Interface (SSI)
Figure 5. Synchronous Serial Interface with Absolute Angular Position Data
t
CLKFE
CSn
T
CLK/2
t
CSn
t
CLKFE
1
1
8
18
CLK
DO
Mag Mag Even
INC DEC PAR
D11
D9 D8
D6 D5
D10
D7
D11
D4 D3 D2 D1 D0 OCF
COF LIN
t
DO valid
t
DO Tristate
t
DO active
Angular Position Data
Status Bits
If CSn changes to logic low, Data Out (DO) will change from high impedance (tri-state) to logic high and the read-out will be initiated.
ꢀ
ꢀ
ꢀ
After a minimum time tCLK FE, data is latched into the output shift register with the first falling edge of CLK.
Each subsequent rising CLK edge shifts out one bit of data.
The serial word contains 18 bits, the first 12 bits are the angular information D[11:0], the subsequent 6 bits contain system information,
about the validity of data such as OCF, COF, LIN, Parity and Magnetic Field status (increase/decrease).
ꢀ
A subsequent measurement is initiated by a “high” pulse at CSn with a minimum duration of tCSn.
8.2.1 Serial Data Contents
D11:D0 – Absolute angular position data (MSB is clocked out first).
OCF – (Offset Compensation Finished). Logic high indicates the finished Offset Compensation Algorithm.
COF – (Cordic Overflow). Logic high indicates an out of range error in the CORDIC part. When this bit is set, the data at D9:D0 is invalid. The
absolute output maintains the last valid angular value. This alarm may be resolved by bringing the magnet within the X-Y-Z tolerance limits.
LIN – (Linearity Alarm). Logic high indicates that the input field generates a critical output linearity. When this bit is set, the data at D9:D0 may still
be used, but can contain invalid data. This warning may be resolved by bringing the magnet within the X-Y-Z tolerance limits.
Even Parity – Bit for transmission error detection of bits 1…17 (D11…D0, OCF, COF, LIN, MagINC, MagDEC). Placing the magnet above the
chip, angular values increase in clockwise direction by default.
Data D11:D0 is valid, when the status bits have the following configurations:
Table 7. Status Bit Outputs
OCF
COF
LIN
Mag INC
Mag DEC
Parity
0
0
1
1
0
1
0
1
Even checksum of bits
1:15
1
0
0
Note: MagInc=MagDec=1 is only recommended in YELLOW mode (see Table 8)
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AS5245
Data Sheet - Detailed Description
8.2.2 Z-axis Range Indication (Push Button Feature, Red/Yellow/Green Indicator)
The AS5245 provides several options of detecting movement and distance of the magnet in the Z-direction. Signal indicators MagINCn and
MagDECn are available both as hardware pins (pins #1 and 2) and as status bits in the serial data stream (see Figure 5). Additionally, an OTP
programming option is available with bit MagCompEn that enables additional features:
In the default state, the status bits MagINC, MagDec and pins MagINCn, MagDECn have the following function:
Table 8. Magnetic Field Strength Red-Yellow-Green Indicator (OTP option)
Status Bits
Hardware Pins
OPT: Mag CompEn = 1 (Red-Yellow-Green Programming Option)
Description
Mag
INC
Mag
DEC
Mag
Mag
LIN
0
INCn
DECn
No distance change
Magnetic input field OK (GREEN range, ~45…75mT)
0
1
1
0
1
1
Off
On
Off
Off
YELLOW range: magnetic field is ~ 25…45mT or ~75…135mT. The AS5245
may still be operated in this range, but with slightly reduced accuracy.
0
RED range: magnetic field is ~<25mT or >~135mT. It is still possible to
operate the AS5245 in the red range, but not recommended.
1
On
n/a
On
n/a
Not available
All other combinations
Note: Pin 1 (MagINCn) and pin 2 (MagDECn) are active low via. open drain output and require an external pull-up resistor. If the magnetic
field is in range, both outputs are turned off.
The two pins may also be combined with a single pull-up resistor. In this case, the signal is high when the magnetic field is in range. It is low in all
other cases (see Table 8).
8.2.3 Incremental Mode
The AS5245 has an internal interpolator block. This function is used if the input magnetic field is too fast and a code position is missing. In this
case an interpolation is done.
With the OTP bits OutputMd0 and OutputMd1 a specific mode can be selected. For the available pre-programmed incremental versions (10bit
and 12bit), these bits are set during test at austriamicrosystems. These settings are permanent and can not be recovered.
A change of the incremental mode (WRITE command) during operation could cause problems. A power-on-reset in between is recommended.
During operation in incremental mode it is recommended setting CSn = High, to disable the SSI-Interface.
Table 9. Incremental Resolution
DTest1_A
and
DTest2_B
Pulses
Output
Md1
Output
Md0
Mode
Description
Resolution
Index Width
AS5245 function DTEST1_A and
DTEST2_B are not used. The
Default mode Mode_Index pin is used for selection of
the decimation rate (low speed/high
speed).
0
0
0
1
10 bit
Incremental
DTEST1_A and DTEST2_B are used as
10
12
256
mode
(low DNL)
A and B signal. In this mode the
1/3
LSB
Mode_Index Pin is switched from input
to output and will be the Index Pin. The
12 bit
Incremental
mode (high
DNL)
decimation rate is set to 64 (fast mode)
1
1
0
1
1024
and cannot be changed from external.
In this mode a control signal is switched
Sync mode
to DTEST1_A and DTEST2_B.
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AS5245
Data Sheet - Detailed Description
Figure 6. Incremental Output
Programmed
Zero Position
Counter ClockWise
ClockWise
D Test1_A
D Test2_B
1 LSB
3 LSB
Mode_Index
The hysteresis trimming is done at the final test (factory trimming) and set to 4 LSB, related to a 12 bit number.
Incremental Output Hysteresis. To avoid flickering incremental outputs at a stationary magnet position, a hysteresis is introduced. In case
of a rotational direction change, the incremental outputs have a hysteresis of 4 LSB. Regardless of the programmed incremental resolution, the
hysteresis of 4 LSB always corresponds to the highest resolution of 12 bit. In absolute terms, the hysteresis is set to 0.35 degrees for all
resolutions. For constant rotational directions, every magnet position change is indicated at the incremental outputs (see Figure 7). For example,
if the magnet turns clockwise from position “x+3“ to “x+4“, the incremental output would also indicate this position accordingly. A change of the
magnet’s rotational direction back to position “x+3“ means that the incremental output still remains unchanged for the duration of 4 LSB, until
position “x+2“is reached. Following this direction, the incremental outputs will again be updated with every change of the magnet position.
Figure 7. Hysteresis Window for Incremental Outputs
Incremental
Output
Hysteresis :
Indication
0.35°
X +6
X +5
X +4
X +3
X +2
X +1
X
Magnet Position
X
X +1 X +2 X +3 X +4 X +5 X +6
Clockwise Direction
Counterclockwise Direction
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Data Sheet - Detailed Description
Incremental Output Validity. During power on the incremental output is kept stable high until the offset compensation is finished and the
CSn is low (internal Pull Up) the first time. In quadrature mode A = B = Index = high indicates an invalid output. If the interpolator recognizes a
difference larger than 128 steps between two samples, it holds the last valid state. The interpolator synchronizes up again with the next valid
difference. This avoids undefined output burst, e.g. if no magnet is present.
8.2.4 Sync Mode
This mode is used to synchronize the external electronic with the AS5245. In this mode, two signals are provided at the pins DTEST1_A and
DTEST2_B. By setting of Md0=1 and Md1=1 in the OTP register, the Sync mode will be activated.
Figure 8. DTest1_A and DTest2_B
400µs (100µs)
DTest1_A
DTest1_B
Every rising edge at DTEST1_A indicates that new data in the device is available. With this signal it is possible to trigger an external customer
Microcontroller (interrupt) and start the SSI readout. DTEST2_B indicates the phase of available data.
8.2.5 Sine/Cosine Mode
This mode can be enabled by setting the OTP Factory-bit FS2. If this mode is activated, the 16 bit sinus and 16 bit cosines digital data of both
channels will be switched out. Due to the high resolution of 16 bits of the data stream, an accurate calculation can be done externally. In this
mode, the open drain outputs of DTEST1_A and DTEST2_B are switched to push-pull mode. At Pin MagDECn the clock impulse, at Pin
MagINCn the Enable pulse will be switched out. The pin PWM indicates, which phase of signal is being presented. The mode is not available in
the default mode.
8.2.6 Daisy Chain Mode
The Daisy Chain mode allows connection of several AS5245s in series, while still keeping just one digital input for data transfer (see “Data IN” in
Figure 9). This mode is accomplished by connecting the data output (DO; pin 9) to the data input (PDIO; pin 8) of the subsequent device. The
serial data of all connected devices is read from the DO pin of the first device in the chain. The length of the serial bit stream increases with every
connected device, it is n * (18+1) bits: n= number of devices. E.g. 38 bit for two devices, 57 bit for three devices, etc.
The last data bit of the first device (Parity) is followed by a dummy bit and the first data bit of the second device (D11), etc. (see Figure 10).
Figure 9. Daisy Chain Hardware Configuration
AS5245
Bottom Die
AS5245
Top Die
AS5245
Top Die
µC
Data IN
PDIO
DO
PDIO
DO
DO
PDIO
CSn
CLK
CSn
CLK
CSn
CLK
CLK
CSn
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AS5245
Data Sheet - Detailed Description
Figure 10. Daisy Chain Mode Data Transfer
CSn
T
CLK/2
t
CLK FE
1
8
D
3
18
1
2
CLK
DO
Mag Mag
INC DEC
Even
PAR
D9
D11 D10
D11
D3 D2
OCF
D1 D0
COF
LIN
D10 D9
D8
D7 D6
D4
D5
t
DO valid
Angular Position Data
nd
Angular Position Data
Status Bits
t
DO active
st
1
2
Device
Device
8.3 Pulse Width Modulation (PWM) Output
The AS5245 provides a pulse width modulated output (PWM), whose duty cycle is proportional to the measured angle. For angle position 0 to
4094:
ton ⋅ 4098
-------------------------
Position =
– 1
(EQ 1)
(ton + toff
)
Examples:
1. An angle position of 180º will generate a pulse width ton = 2049µs and a pause tOFF of 2049 µs resulting in Position = 2048 after the
calculation: 2049 * 4098 / (2049 + 2049) -1 = 2048
2. An angle position of 359.8º will generate a pulse width ton = 4095µs and a pause tOFF of 3 µs resulting in Position = 4094 after the cal-
culation: 4095 * 4098 / (4095 + 3) -1 = 4094
Exception:
1. An angle position of 359.9º will generate a pulse width ton = 4097µs and a pause tOFF of 1 µs resulting in Position = 4096 after the cal-
culation: 4097 * 4098 / (4097 + 1) -1 = 4096
The PWM frequency is internally trimmed to an accuracy of ±5% (±10% over full temperature range). This tolerance can be cancelled by
measuring the complete duty cycle as shown above.
Figure 11. PWM Output Signal
Angle
PW
MIN
0 deg
(Pos 0)
1µs
4097µs
PW
MAX
359.91 deg
(Pos 4095)
4096µs
1/f
PWM
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Data Sheet - Detailed Description
8.3.1 Changing the PWM Frequency
The PWM frequency of the AS5245 can be divided by two by setting a bit (PWMhalfEN) in the OTP register (see Programming the AS5245 on
page 17). With PWMhalfEN = 0, the PWM timing is as shown in Table 10:
Table 10. PWM Signal Parameters (Default mode)
Symbol
Parameter
Typ
Unit
Note
fPWM
Signal period: 4097µs
PWM frequency
244
Hz
- Position 0d
- Angle 0 deg
PWMIN
PWMAX
MIN pulse width
MAX pulse width
1
µs
µs
- Position 4095d
- Angle 359,91 deg
4096
When PWMhalfEN = 1, the PWM timing is as shown in Table 11:
Table 11. PWM Signal Parameters with Half Frequency (OTP option)
Symbol
Parameter
Typ
Unit
Note
- Position 0d
- Angle 0 deg
fPWM
PWM frequency
122
Hz
- Position 4095d
- Angle 359,91 deg
PWMIN
PWMAX
MIN pulse width
MAX pulse width
2
µs
µs
- Position 0d
- Angle 0 deg
8192
8.4 Analog Output
An analog output can be generated by averaging the PWM signal, using an external active or passive low pass filter. The analog output voltage
is proportional to the angle: 0º= 0V; 360º = VDD5V.
Using this method, the AS5245 can be used as direct replacement of potentiometers.
Figure 12. Simple 2nd Order Passive RC Low Pass Filter
R2
R1
analog out
Pin12
PWM
VDD
0V
C2
C1
Pin7
VSS
0º
360º
Figure 12 shows an example of a simple passive low pass filter to generate the analog output.
R1,R2 ≥ 4k7 C1,C2 ≥ 1µF / 6V
(EQ 2)
R1 should be greater than or equal to 4k7 to avoid loading of the PWM output. Larger values of Rx and Cx will provide better filtering and less
ripple, but will also slow down the response time.
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AS5245
Data Sheet - Application Information
9 Application Information
The benefits of AS5245 are as follows:
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Complete system-on-chip
Angle measurement with programmable range up to 360º
High reliability due to non-contact magnetic sensing
Ideal for applications in harsh environments
Robust system, tolerant to magnet misalignment, airgap variations, temperature variations and external magnetic fields
No calibration required
Building of redundancy systems with plausibility checks
9.1 Programming the AS5245
After power-on, programming the AS5245 is enabled with the rising edge of CSn with PDIO = high and CLK = low.
The AS5245 programming is a one-time programming (OTP) method, based on poly silicon fuses. The advantage of this method is that a
programming voltage of only 3.3V to 3.6V is required for programming.
The OTP consists of 52 bits, of which 21 bits are available for user programming. The remaining 31 bits contain factory settings and a unique
chip identifier (Chip-ID).
A single OTP cell can be programmed only once. Per default, the cell is “0”; a programmed cell will contain a “1”. While it is not possible to reset
a programmed bit from “1” to “0”, multiple OTP writes are possible, as long as only unprogrammed “0”-bits are programmed to “1”.
Independent of the OTP programming, it is possible to overwrite the OTP register temporarily with an OTP write command at any time. This
setting will be cleared and overwritten with the hard programmed OTP settings at each power-up sequence or by a LOAD operation. Use
application note AN514X_10 to get more information about the programming options.
The OTP memory can be accessed in the following ways:
ꢀ
ꢀ
Load Operation: The Load operation reads the OTP fuses and loads the contents into the OTP register. A Load operation is automatically
executed after each power-on-reset.
Write Operation: The Write operation allows a temporary modification of the OTP register. It does not program the OTP. This operation can
be invoked multiple times and will remain set while the chip is supplied with power and while the OTP register is not modified with another
Write or Load operation.
ꢀ
Read Operation: The Read operation reads the contents of the OTP register, for example to verify a Write command or to read the OTP
memory after a Load command.
ꢀ
ꢀ
Program Operation: The Program operation writes the contents of the OTP register permanently into the OTP ROM.
Analog Readback Operation: The Analog Readback operation allows a quantifiable verification of the programming. For each
programmed or unprogrammed bit, there is a representative analog value (in essence, a resistor value) that is read to verify whether a bit
has been successfully programmed or not.
9.1.1 Zero Position Programming
Zero position programming is an OTP option that simplifies assembly of a system, as the magnet does not need to be manually adjusted to the
mechanical zero position. Once the assembly is completed, the mechanical and electrical zero positions can be matched by software. Any
position within a full turn can be defined as the permanent new zero position.
For zero position programming, the magnet is turned to the mechanical zero position (e.g. the “off”-position of a rotary switch) and the actual
angular value is read.
This value is written into the OTP register bits Z35:Z46.
Note: The zero position value may also be modified before programming, e.g. to program an electrical zero position that is 180º (half turn)
from the mechanical zero position, just add 2048 to the value read at the mechanical zero position and program the new value into the
OTP register.
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Data Sheet - Application Information
9.1.2 OTP Memory Assignment
Table 12. OTP Bit Assignment
Bit
Symbol
Function
Factory Bit 1
mbit1
51
50
49
48
47
46
:
PWMhalfEN_Index width
PMW frequency Index pulse width
Alarm mode
MagCompEn
pwmDIS
Output Md0
Output Md1
Z0
Disable PWM
Default, 10 bit inc, 12 bit inc
Sync mode
:
12 bit Zero Position
Direction
35
34
33
:
Z11
CCW
RA0
:
Redundancy Address
29
28
27
26
25
24
23
:
RA4
FS 0
FS 1
FS 2
FS 3
Factory Bit
FS 4
FS 5
:
20
17
16
:
FS 9
ChipID0
ChipID1
:
18 bit Chip ID
Factory Bit 0
0
ChipID17
mbit0
9.1.3 User Selectable Settings
The AS5245 allows programming of the following user selectable options:
- PWMhalfEN_Indexwidth: Setting this bit, the PWM pulse will be divided by 2, in case of quadrature incremental mode A/B/Index setting
of Index impulse width from 1 LSB to 3LSB.
- MagCompEN: The green/yellow mode can be enabled by setting of this bit.
- Output Md0: Setting this bit enables sync- or 10bit incremental mode (see Table 9). It is already set by Austriamicrosystems.
- Output Md1: Setting this bit enables sync- or 12bit incremental mode (see Table 9)
- Z [11:0]: Programmable Zero / Index Position
- CCW: Counter Clockwise Bit
ccw=0 – angular value increases in clockwise direction
ccw=1 – angular value increases in counterclockwise direction
- RA [4:0]: Redundant Address: an OTP bit location addressed by this address is always set to “1” independent of the corresponding
original OTP bit setting
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Data Sheet - Application Information
9.1.4 OTP Default Setting
The AS5245 can also be operated without programming. The default, un-programmed setting is:
- Output Md0, Output MD1: 00= Default mode
- Z0 to Z11: 00 = no programmed zero position
- CCW: 0 = clockwise operation
- RA4 to RA0:0 = no OTP bit is selected
- MagCompEN: 1 = The green / yellow mode is enabled.
9.1.5 Redundancy
For a better programming reliability, a redundancy is implemented. This function can be used in cases where the programming of one bit fails.
With an address RA(4:0), one bit can be selected and programmed.
Table 13. Redundancy Addressing
Address
Z0
Z1
Z2
Z3
Z4
Z5
Z6
Z7
Z8
Z9 Z10 Z11 CCW
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
10000
10001
10010
10101
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
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
1
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
9.1.6 Redundant Programming Option
In addition to the regular programming, a redundant programming option is available. This option allows that one selectable OTP bit can be set
to “1” (programmed state) by writing the location of that bit into a 5-bit address decoder. This address can be stored in bits RA4…RA0 in the OTP
user settings.
Example: setting RA4…0 to “00001” will select bit 51 = PWhalfEN_Indexwidth, “00010” selects bit 50 = MagCompEN, “10010” selects bit 34
=CCW, etc.
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Data Sheet - Application Information
9.2 Alignment Mode
The alignment mode simplifies centering the magnet over the center of the chip to gain maximum accuracy.
Alignment mode can be enabled with the falling edge of CSn while PDIO = logic high (see Figure 13). The Data bits D11-D0 of the SSI change to
a 12-bit displacement amplitude output. A high value indicates large X or Y displacement, but also higher absolute magnetic field strength. The
magnet is properly aligned, when the difference between highest and lowest value over one full turn is at a minimum.
Under normal conditions, a properly aligned magnet will result in a reading of less than 128 over a full turn.
The MagINCn and MagDECn indicators will be = 1 when the alignment mode reading is < 128. At the same time, both hardware pins MagINCn
(#1) and MagDECn (#2) will be pulled to VSS. A properly aligned magnet will therefore produce a MagINCn = MagDECn = 1 signal throughout a
full 360º turn of the magnet.
Stronger magnets or short gaps between magnet and IC may show values larger than 128. These magnets are still properly aligned as long as
the difference between highest and lowest value over one full turn is at a minimum.
The Alignment mode can be reset to normal operation by a power-on-reset (disconnect / re-connect power supply) or by a falling edge on CSn
with PDIO = low.
Figure 13. Enabling the Alignment Mode
PDIO
Read-out
via SSI
AlignMode enable
CSn
2µs
min.
2µs
min.
Figure 14. Exiting Alignment Mode
PDIO
CSn
Read-out
via SSI
exit AlignMode
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Data Sheet - Application Information
9.3 3.3V / 5V Operation
The AS5245 operates either at 3.3V ±10% or at 5V ±10%. This is made possible by an internal 3.3V Low-Dropout (LDO) Voltage regulator. The
internal supply voltage is always taken from the output of the LDO, meaning that the internal blocks are always operating at 3.3V.
For 3.3V operation, the LDO must be bypassed by connecting VDD3V3 with VDD5V (see Figure 15).
For 5V operation, the 5V supply is connected to pin VDD5V, while VDD3V3 (LDO output) must be buffered by a 1...10µF capacitor, which is
supposed to be placed close to the supply pin (see Figure 15).
Note: The VDD3V3 output is intended for internal use only. It must not be loaded with an external load.
The output voltage of the digital interface I/O’s corresponds to the voltage at pin VDD5V, as the I/O buffers are supplied from this pin.
Figure 15. Connections for 5V / 3.3V Supply Voltages
5V Operation
3.3V Operation
VDD5V
1... 10µF
VDD3V3
VDD3V3
100n
100n
Internal
VDD
Internal
VDD
VDD5V
LDO
LDO
DO
DO
+
+
I
PWM
CLK
CSn
I
PWM
CLK
CSn
N
T
E
R
F
A
C
E
N
T
E
R
F
A
C
E
3.0 - 3.6V
4.5 - 5.5V
PDIO
PDIO
VSS
VSS
A buffer capacitor of 100nF is recommended in both cases close to pin VDD5V. Note that pin VDD3V3 must always be buffered by a capacitor. It
must not be left floating, as this may cause an instable internal 3.3V supply voltage, which may lead to larger than normal jitter of the measured
angle.
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Data Sheet - Application Information
9.4 Choosing the Proper Magnet
Typically, the magnet should be 6mm in diameter and ≥ 2.5mm in height. Magnetic materials such as rare earth AlNiCo/SmCo5 or NdFeB are
recommended. The magnetic field strength perpendicular to the die surface has to be in the range of ±45mT…±75mT (peak).
The magnet’s field strength should be verified using a gauss-meter. The magnetic field Bv at a given distance, along a concentric circle with a
radius of 1.1mm (R1), should be in the range of ±45mT…±75mT (see Figure 16).
Figure 16. Typical Magnet (6x3mm) and Magnetic Field Distribution
typ. 6mm diameter
N
S
Magnet axis
R1
Vertical field
component
R1 concentric circle;
radius 1.1mm
Vertical field
component
Bv
(45…75mT)
360
0
360
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Data Sheet - Application Information
9.5 Failure Diagnostics
The AS5245 also offers several diagnostic and failure detection features, which are discussed in detail further in the document.
9.5.1 Magnetic Field Strength Diagnosis
By Software: The MagINC and MagDEC status bits will both be high when the magnetic field is out of range.
By Hardware: Pins #1 (MagINCn) and #2 (MagDECn) are open-drain outputs and will both be turned on (= low with external pull-up resistor)
when the magnetic field is out of range. If only one of the outputs are low, the magnet is either moving towards the chip (MagINCn) or away from
the chip (MagDECn).
9.5.2 Power Supply Failure Detection
By Software: If the power supply to the AS5245 is interrupted, the digital data read by the SSI will be all “0”s. Data is only valid, when bit OCF is
high, hence a data stream with all “0”s is invalid. To ensure adequate low levels in the failure case, a pull-down resistor (~10kΩ) should be added
between pin DIO and VSS at the receiving side.
By Hardware: The MagINCn and MagDECn pins are open drain outputs and require external pull-up resistors. In normal operation, these pins
are high ohmic and the outputs are high (see Table 8). In a failure case, either when the magnetic field is out of range of the power supply is
missing, these outputs will become low. To ensure adequate low levels in case of a broken power supply to the AS5245, the pull-up resistors
(~10kΩ) from each pin must be connected to the positive supply at pin 16 (VDD5V).
By Hardware, PWM Output: The PWM output is a constant stream of pulses with 1kHz repetition frequency. In case of power loss, these pulses
are missing.
9.6 Angular Output Tolerances
9.6.1 Accuracy
Accuracy is defined as the error between measured angle and actual angle. It is influenced by several factors:
ꢀ
ꢀ
ꢀ
The non-linearity of the analog-digital converters,
Internal gain and mismatch errors,
Non-linearity due to misalignment of the magnet.
As a sum of all these errors, the accuracy with centered magnet = (Errmax – Errmin)/2 is specified as better than ±0.5 degrees @ 25ºC (see
Figure 19).
Misalignment of the magnet further reduces the accuracy. Figure 18 shows an example of a 3D-graph displaying non-linearity over XY-
misalignment. The center of the square XY-area corresponds to a centered magnet (see dot in the center of the graph). The X- and Y- axis
extends to a misalignment of ±1mm in both directions. The total misalignment area of the graph covers a square of 2x2 mm (79x79mil) with a
step size of 100µm.
For each misalignment step, the measurement as shown in Figure 19 is repeated and the accuracy (Errmax – Errmin)/2 (e.g. 0.25º in Figure 19) is
entered as the Z-axis in the 3D-graph.
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Data Sheet - Application Information
Figure 17. Example of Linearity Error Over XY Misalignment
6
5
4
°
3
800
500
200
2
1
0
-100
-400
-700
-1000
x
y
The maximum non-linearity error on this example is better than ±1 degree (inner circle) over a misalignment radius of ~0.7mm. For volume
production, the placement tolerance of the IC within the package (±0.235mm) must also be taken into account. The total nonlinearity error over
process tolerances, temperature and a misalignment circle radius of 0.25mm is specified better than ±1.4 degrees. The magnet used for this
measurement was a cylindrical NdFeB (Bomatec® BMN-35H) magnet with 6mm diameter and 2.5mm in height.
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AS5245
Data Sheet - Application Information
Figure 18. Example of Linearity Error Over 360º
0.5
0.4
0.3
0.2
0.1
0
transition noise
Err max
1
55
109
163
217
271
325
379
433
487
541
595
649
703
757
811
865
919
973
-0.1
-0.2
-0.3
-0.4
-0.5
Errmin
9.6.2 Transition Noise
Transition noise is defined as the jitter in the transition between two steps. Due to the nature of the measurement principle (Hall sensors +
Preamplifier + ADC), there is always a certain degree of noise involved. This transition noise voltage results in an angular transition noise at the
outputs. It is specified as 0.06 degrees rms (1 sigma)1 in fast mode (pin MODE = high) and 0.03 degrees rms (1 sigma) in slow mode (pin MODE
= low or open). This is the repeatability of an indicated angle at a given mechanical position. The transition noise has different implications on the
type of output that is used:
ꢀ
ꢀ
ꢀ
Absolute Output; SSI Interface: The transition noise of the absolute output can be reduced by the user by implementing averaging of
readings. An averaging of 4 readings will reduce the transition noise by 6dB or 50%, e.g. from 0.03º rms to 0.015º rms (1 sigma) in slow
mode.
PWM Interface: If the PWM interface is used as an analog output by adding a low pass filter, the transition noise can be reduced by lower-
ing the cutoff frequency of the filter. If the PWM interface is used as a digital interface with a counter at the receiving side, the transition
noise may again be reduced by averaging of readings.
Incremental Mode: In incremental mode, the transition noise influences the period, width and phase shift of the output signals A, B and
Index. However, the algorithm used to generate the incremental outputs guarantees no missing or additional pulses even at high speeds (up
to 30.000 rpm and higher).
9.6.3 High Speed Operation
Sampling Rate. The AS5245 samples the angular value at a rate of 2.61k (slow mode) or 10.42k (fast mode, selectable by pin MODE)
samples per second. Consequently, the absolute outputs are updated each 384µs (96µs in fast mode). At a stationary position of the magnet,
the sampling rate creates no additional error.
Absolute Mode. At a sampling rate of 2.6kHz/10.4kHz, the number of samples (n) per turn for a magnet rotating at high speed can be
calculated by,
60
----------------------------------
nslowmode
nfastmode
=
(EQ 3)
(EQ 4)
rpm ⋅ (384)μs
60
--------------------------
=
rmp ⋅ 96μs
The upper speed limit in slow mode is ~6.000rpm and ~30.000rpm in fast mode. The only restriction at high speed is that there will be fewer
samples per revolution as the speed increases (see Table 6). Regardless of the rotational speed, the absolute angular value is always sampled
at the highest resolution of 12 bit.
1. Statistically, 1 sigma represents 68.27% of readings; 3 sigma represents 99.73% of readings.
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AS5245
Data Sheet - Application Information
Incremental Mode. Incremental encoders are usually required to produce no missing pulses up to several thousand rpms. Therefore, the
AS5245 has a built-in interpolator, which ensures that there are no missing pulses at the incremental outputs for rotational speeds of up to
30.000 rpm, even at the highest resolution of 10 bits (512 pulses per revolution).
9.6.4 Propagation Delays
The propagation delay is the delay between the time that the sample is taken until it is converted and available as angular data. This delay is
96µs in fast mode and 384µs in slow mode.
Using the SSI interface for absolute data transmission, an additional delay must be considered, caused by the asynchronous sampling (0 … 1/
fsample) and the time it takes the external control unit to read and process the angular data from the chip (maximum clock rate = 1MHz, number
of bits per reading = 18).
Angular Error Caused by Propagation Delay. A rotating magnet will cause an angular error caused by the output propagation delay.
This error increases linearly with speed:
esampling = rpm * 6 * prop.delay
(EQ 5)
Where:
esampling = angular error [º]
rpm = rotating speed [rpm]
prop.delay = propagation delay [seconds]
Note: Since the propagation delay is known, it can be automatically compensated by the control unit processing the data from the AS5245.
9.6.5 Internal Timing Tolerance
The AS5245 does not require an external ceramic resonator or quartz. All internal clock timings for the AS5245 are generated by an on-chip RC
oscillator. This oscillator is factory trimmed to ±5% accuracy at room temperature (±10% over full temperature range). This tolerance influences
the ADC sampling rate and the pulse width of the PWM output:
ꢀ
Absolute Output; SSI Interface: A new angular value is updated every 96µs (typ) in fast mode and every 384µs (typ) in slow mode.
ꢀ
PWM Output: A new angular value is updated every 400µs (typ). The PWM pulse timings tON and tOFF also have the same tolerance as
the internal oscillator. If only the PWM pulse width tON is used to measure the angle, the resulting value also has this timing tolerance.
However, this tolerance can be cancelled by measuring both tON and tOFF and calculating the angle from the duty cycle (see Pulse Width
Modulation (PWM) Output on page 15).
ꢀ
Incremental Mode: In incremental mode, the transition noise influences the period, width and phase shift of the output signals A, B and
Index. However, the algorithm used to generate the incremental outputs guarantees no missing or additional pulses even at high speeds (up
to 30.000 rpm and higher).
ton ⋅ 4097
-------------------------
Position =
– 1
(EQ 6)
(ton + toff
)
9.6.6 Temperature
Magnetic Temperature Coefficient. One of the major benefits of the AS5245 compared to linear Hall sensors is that it is much less
sensitive to temperature. While linear Hall sensors require a compensation of the magnet’s temperature coefficients, the AS5245 automatically
compensates for the varying magnetic field strength over temperature. The magnet’s temperature drift does not need to be considered, as the
AS5245 operates with magnetic field strengths from ±45…±75mT.
Example:
A NdFeB magnet has a field strength of 75mT @ -40ºC and a temperature coefficient of -0.12% per Kelvin. The temperature change is from -40º
to +125º = 165K.The magnetic field change is: 165 x -0.12% = -19.8%, which corresponds to 75mT at -40ºC and 60mT at 125ºC.
The AS5245 can compensate for this temperature related field strength change automatically, no user adjustment is required.
9.6.7 Accuracy over Temperature
The influence of temperature in the absolute accuracy is very low. While the accuracy is less than or equal to ±0.5º at room temperature, it may
increase to less then or equal to ±0.9º due to increasing noise at high temperatures.
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AS5245
Data Sheet - Application Information
Timing Tolerance over Temperature. The internal RC oscillator is factory trimmed to ±5%. Over temperature, this tolerance may increase
to ±10%. Generally, the timing tolerance has no influence in the accuracy or resolution of the system, as it is used mainly for internal clock
generation. The only concern to the user is the width of the PWM output pulse, which relates directly to the timing tolerance of the internal
oscillator. This influence, however, can be cancelled by measuring the complete PWM duty cycle instead of just the PWM pulse.
9.7 AS5245 Differences to AS5045
All parameters are according to AS5045 data sheet except for the parameters shown below:
Table 14. Difference Between AS5245 and AS5045
Building Block
Resolution
AS5245
AS5045
12bits, 0.088º/step.
-40ºC to +150ºC
read: 18bits
12bits, 0.088º/step.
-40ºC to +125ºC
read: 18bits
Ambient temperature range
(12bits data + 6 bits status)
OTP write: 18 bits
(12bits zero position + 6 bits mode selection)
(12bits data + 6 bits status)
OTP write: 18 bits
(12bits zero position + 6 bits mode selection)
Data length
Pins 1 and 2
MagINCn, MagDECn: same feature as AS5045,
additional OTP option for red-yellow-green magnetic
range
MagINCn, MagDECn
Not used
Pin 3: not used
Pin 4:not used
Pin3 (DTest1_A); Pin 4 (DTest2_B); Pin 6 (Mode_Index)
2x1024 ppr (12-bit)
2x256 ppr low-jitter (10-bit)
Incremental encoder
MODE_Index pin selects fast or slow mode in the
default configuration. In case of incremental mode, the MODE_Index pin selects fast or slow mode in the
Pin 6
fast mode is selected and the pin is configured as
output.
default configuration.
PWM output: frequency selectable by OTP:
1µs / step, 4096 steps per revolution, f=244Hz 2µs/
step, 4096 steps per revolution, f=122Hz
PWM output: frequency selectable by OTP:
1µs / step, 4096 steps per revolution, f=244Hz
2µs/ step, 4096 steps per revolution, f=122Hz
Pin 12
selectable by MODE input pin:
2.5kHz, 10,4kHz
selectable by MODE input pin:
2.5kHz, 10,4kHz
Sampling frequency
Propagation delay
384µs (slow mode)
384µs (slow mode)
96µs (fast mode)
96µs (fast mode)
0.03 degrees maximum (slow mode)
0.06 degrees maximum (fast mode)
0.03 degrees maximum (slow mode)
0.06 degrees maximum (fast mode)
Transition noise
(rms; 1sigma)
PPTRIM; programming voltage 3.3V – 3.6V <70ºC;
3.5V – 3.6V >70ºC;
52-bit serial data protocol; CSn, PDIO and CLK
EasyZap; programming voltage 7.3V – 7.5V; Csn;
Prog and CLK; 16-bit (32-bit) serial data protocol;
OTP programming options
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AS5245
Data Sheet - Pack age Drawings and Markings
10 Package Drawings and Markings
The device is available in a QFN 32 (7mm x 7mm) package.
Figure 19. Package Drawings
AS5245
25
32
Top View
24
1
8
17
16
9
Side View
Bottom View
Table 15. Package Dimensions
mm
inch
Typ
Symbol
Min
Typ
7 BSC
7 BSC
4.28
Max
Min
Max
D
E
0.28 BSC
0.28 BSC
0.169
D1
E1
L
4.18
4.18
0.45
0.25
4.38
4.38
0.65
0.35
0.165
0.165
0.018
0.010
0.172
0.172
0.026
0.014
4.28
0.169
0.55
0.022
b
0.30
0.012
e
0.65 BSC
0.90
A
0.80
1.00
0.031
0.035
0.039
A1
0.203 REF
0.008 REF
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AS5245
Data Sheet - Revision History
Revision History
Revision
Date
Owner
Description
Initial revision
June 08, 2007
July 24, 2008
Changes made to values in Table 9 - Incremental Resolution
apg
Updated min, typ, max values for tDOvalid parameter in Table 5 - Timing
Characteristics
Feb 13, 2009
July 15, 2009
1) Note added under Table 6 - Slow and Fast Mode Parameters
2) Output Md0, Md1 description updated, (see User Selectable Settings
on page 18)
rfu
Updated values in Table 5 - Timing Characteristics for the following
1.0
parameters:
- tDOvalid
July 22, 2009
July 23, 2009
- fPWM
- PWMIN
- PWMAX
mub
Updated sections Electrical Characteristics on page 6, Timing
Characteristics on page 9 and Detailed Description on page 10
according to AS5145 datasheet.
Deleted the following --
1) ‘OTP Programming Connection’ figure
2) Physical Placement of the magnet, Magnet Placement, Simulation
Modeling
1.1
Oct 19, 2009
Nov 05, 2009
Timing Characteristics (page 9) - Deleted the parameter ‘PWM
apg
1.2
1.3
Frequency’ (fPWM
)
Updated section Internal Timing Tolerance (page 26)
Updated standards in Absolute Maximum Ratings on page 5
Updated Package Drawings and Markings on page 28
Dec 04, 2009
Apr 01, 2010
Apr 13, 2010
1.4
1.5
Updated Mode_Index, PWM, Electrical Characteristics (page 6),
fPWM (page 9), Figure 9, Table 11.
Jun 17, 2010
mub
Info on ‘Magnet Input Specification’ deleted from the document.
Note: Typos may not be explicitly mentioned under revision history.
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AS5245
Data Sheet - Ordering Information
11 Ordering Information
The devices are available as the standard products shown in Table 16.
Table 16. Ordering Information
Ordering Code
Description
Delivery Form
Package
AS5245HQFT
12-bit fully redundant magnetic rotary encoder
Tape & Reel
QFN 32 (7mm x 7mm)
Note: All products are RoHS compliant and Pb-free.
Buy our products or get free samples online at ICdirect: http://www.austriamicrosystems.com/ICdirect
For further information and requests, please contact us mailto:sales@austriamicrosystems.com
or find your local distributor at http://www.austriamicrosystems.com/distributor
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AS5245
Data Sheet - Copyrights
Copyrights
Copyright © 1997-2010, austriamicrosystems AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®.
All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of
the copyright owner.
All products and companies mentioned are trademarks or registered trademarks of their respective companies.
Disclaimer
Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale.
austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding
the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at
any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for
current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range,
unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are
specifically not recommended without additional processing by austriamicrosystems AG for each application. For shipments of less than 100
parts the manufacturing flow might show deviations from the standard production flow, such as test flow or test location.
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