AS5045B Datasheet

A S5 04 5B
12-Bit Programmable Magnetic Position Sensor
1 General Description
Two digital 12-bit absolute outputs:
The AS5045B is a contact less magnetic position sensor for accurate
angular measurement over a full turn of 360 degrees.
It is a system-on-chip, combining integrated Hall elements, analog
front end and digital signal processing in a single device.
- Serial interface
- Pulse width modulated (PWM) output
Quadrature A/B/I output 12-bit
User programmable zero position
To measure the angle, only a simple two-pole magnet, rotating over
the center of the chip, is required. The magnet can be placed above
or below the IC.
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.
Failure detection mode for magnet placement, monitoring, and
loss of power supply
Red-Yellow-Green indicators display placement of magnet in Z-
axis
Serial read-out of multiple interconnected AS5045B devices
using Daisy Chain mode
Tolerant to magnet misalignment and gap variations
An internal voltage regulator allows the AS5045B to operate at either
3.3V or 5V supplies.
Wide temperature range: - 40ºC to +125ºC
Small Pb-free package: SSOP 16 (5.3mm x 6.2mm)
3 Applications
2 Key Features
Contact less high resolution rotary position sensor over a full
turn of 360 degrees
The device is ideal for industrial applications like automatic or
elevator doors, robotics, motor control and optical encoder
replacement.
Figure 1. Blockdiagram Rotary Position Sensor IC
VDD3V3
MagINCn
VDD5V
MagDECn
LDO 3.3V
PWM
Interface
Sin
Hall Array
&
Frontend
Amplifier
Cos
PWM
Ang
ATAN
(Cordic)
Mag
Absolute
Interface
(SSI)
DO
CSn
CLK
OTP
Register
PDIO
A
AS5045B
Incremental
Interface
B
I
www.ams.com
Revision 1.0
1 - 33
AS5045B
Datasheet - C o n t e n t s
Contents
1 General Description ..................................................................................................................................................................
1
2 Key Features.............................................................................................................................................................................
1
3 Applications...............................................................................................................................................................................
1
4 Pin Assignments .......................................................................................................................................................................
3
4.1 Pin Descriptions....................................................................................................................................................................................
3
5 Absolute Maximum Ratings ......................................................................................................................................................
5
6 Electrical Characteristics...........................................................................................................................................................
6
6.1 Magnetic Input Specification.................................................................................................................................................................
7
6.2 System Specifications ..........................................................................................................................................................................
8
7 Timing Characteristics ............................................................................................................................................................
10
8 Detailed Description................................................................................................................................................................
11
8.1 Synchronous Serial Interface (SSI) ....................................................................................................................................................
11
8.2 Incremental Mode...............................................................................................................................................................................
13
8.3 Daisy Chain Mode ..............................................................................................................................................................................
14
8.4 Pulse Width Modulation (PWM) Output..............................................................................................................................................
15
8.4.1 Changing the PWM Frequency.................................................................................................................................................. 16
8.5 Analog Output.....................................................................................................................................................................................
9 Application Information ...........................................................................................................................................................
17
9.1 Programming the AS5045B................................................................................................................................................................
9.1.1
9.1.2
9.1.3
9.1.4
9.1.5
9.1.6
9.1.7
16
Zero Position Programming .......................................................................................................................................................
OTP Memory Assignment..........................................................................................................................................................
User Selectable Settings ...........................................................................................................................................................
OTP Default Setting...................................................................................................................................................................
Redundancy...............................................................................................................................................................................
Redundant Programming Option ...............................................................................................................................................
OTP Register Entry and Exit Condition .....................................................................................................................................
9.2 Alignment Mode..................................................................................................................................................................................
17
17
18
18
19
19
20
20
21
9.3 3.3V / 5V Operation ............................................................................................................................................................................
22
9.4 Selecting Proper Magnet ....................................................................................................................................................................
22
9.4.1 Physical Placement of the Magnet ............................................................................................................................................ 23
9.4.2 Magnet Placement..................................................................................................................................................................... 24
9.5 Failure Diagnostics .............................................................................................................................................................................
24
9.5.1 Magnetic Field Strength Diagnosis ............................................................................................................................................ 24
9.5.2 Power Supply Failure Detection ................................................................................................................................................ 24
9.6 Angular Output Tolerances .................................................................................................................................................................
9.6.1
9.6.2
9.6.3
9.6.4
9.6.5
9.6.6
9.6.7
Accuracy ....................................................................................................................................................................................
Transition Noise.........................................................................................................................................................................
High Speed Operation ...............................................................................................................................................................
Propagation Delays ...................................................................................................................................................................
Internal Timing Tolerance ..........................................................................................................................................................
Temperature ..............................................................................................................................................................................
Accuracy over Temperature ......................................................................................................................................................
10 Package Drawings and Markings .........................................................................................................................................
www.ams.com
Revision 1.0
24
26
26
26
27
27
27
28
10.1 Recommended PCB Footprint..........................................................................................................................................................
11 Ordering Information .............................................................................................................................................................
24
30
32
2 - 33
AS5045B
Datasheet - P i n A s s i g n m e n t s
4 Pin Assignments
Figure 2. Pin Assignments (Top View)
1
16
VDD5V
MagDECn
2
15
VDD3V3
A
3
14
NC
B
4
13
NC
NC
5
12
PWM
I
6
11
CSn
VSS
7
10
CLK
PDIO
8
9
DO
AS5045B
MagINCn
4.1 Pin Descriptions
The following SSOP16 shows the description of each pin of the standard SSOP16 package (Shrink Small Outline Package, 16 leads, body size:
5.3mm x 6.2mmm; (see Figure 2).
Table 1. Pin Descriptions
Pin Name
Pin Number
MagINCn
1
MagDECn
2
A
3
B
4
NC
5
-
I
6
Digital output
VSS
7
Supply pin
PDIO
8
OTP Programming Input and Data Input for Daisy Chain mode. Pin
Digital input pull-down has an internal pull-down resistor (74kΩ). Connect this pin to VSS if
programming is not required.
DO
9
Digital output/ tri-state Data Output of Synchronous Serial Interface
CLK
10
Digital input, Schmitt- Clock Input of Synchronous Serial Interface; Schmitt-Trigger input
Trigger input
www.ams.com
Pin Type
Digital output open
drain
Digital output
Description
Magnet Field Magnitude Increase. Active low. Indicates a distance
reduction between the magnet and the device surface. (see Table 8)
Magnet Field Magnitude Decrease. Active low. Indicates a distance
increase between the device and the magnet. (see Table 8)
Quadrature output A (1024 Pulses)
Quadrature output B (1024 Pulses)
Must be left unconnected
Index signal for the quadrature output.
Negative Supply Voltage (GND)
Revision 1.0
3 - 33
AS5045B
Datasheet - P i n A s s i g n m e n t s
Table 1. Pin Descriptions
Pin Name
Pin Number
Pin Type
Description
CSn
11
PWM
12
Digital output
Pulse Width Modulation
NC
13
-
Must be left unconnected
NC
14
-
Must be left unconnected
VDD3V3
15
Supply pin
3V-Regulator Output, internally regulated from VDD5V. Connect to
VDD5V for 3V supply voltage. Do not load externally.
VDD5V
16
Supply pin
Positive Supply Voltage, 3.0V to 5.5V
Digital input pullChip Select. Active low. Schmitt-Trigger input, internal pull-up resistor
down, Schmitt-Trigger
(50kΩ)
input
Pin 1 and 2 are the magnetic field change indicators, MagINCn and MagDECn (magnetic field strength increase or decrease through variation of
the distance between the magnet and the device). These outputs can be used to detect the valid magnetic field range. Furthermore those
indicators can also be used for contact-less push-button functionality.
Pin 3 and 4 are used for incremental angle information in 12-bit quadrature signal format.
Pin 6 Index output used for incremental angle information. (Zero position reference).
Pins 7, 15, and 16 are supply pins, pins 5, 13, and 14 are for internal use and must not be connected.
Pin 8 (PDIO) is used to program the zero-position into the OTP(see page 17). This pin is also used as digital input to shift serial data through the
device in Daisy Chain configuration, (see page 13).
Pin 11 Chip Select (CSn; active low) selects a device within a network of AS5045Bs and initiates serial data transfer. A logic high at CSn puts the
data output pin (DO) to tri-state and terminates serial data transfer. This pin is also used for alignment mode (see Alignment Mode on page 21)
and programming mode (see Programming the AS5045B on page 17).
Pin 12 allows a single wire output of the 12-bit absolute position value. The value is encoded into a pulse width modulated signal with 1µs pulse
width per step (1µs to 4096µs over a full turn). By using an external low pass filter, the digital PWM signal is converted into an analog voltage,
e.g. for making a direct replacement of potentiometers possible.
www.ams.com
Revision 1.0
4 - 33
AS5045B
Datasheet - A b s o l u t e M a x i m u m R a t i n g s
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 Section 6 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
Max
Units
-0.3
7
V
5
V
Comments
Electrical Parameters
DC supply voltage at pin VDD5V
DC supply voltage at pin VDD3V3
Input pin voltage
-0.3
VDD5V +0.3
V
Except VDD3V3
Input current (latchup immunity)
-100
100
mA
Norm: EIA/JESD78 Class II Level A
±2
kV
Norm: JESD22-A114E
150
ºC
Min -67ºF; Max +302ºF
260
ºC
The reflow peak soldering temperature (body
temperature) specified is in accordance with IPC/
JEDEC J-STD-020 “Moisture/Reflow Sensitivity
Classification for Non-Hermetic Solid State Surface
Mount Devices”.
The lead finish for Pb-free leaded packages is matte tin
(100% Sn).
85
%
Electrostatic Discharge
Electrostatic discharge
Temperature Ranges and Storage Conditions
Storage temperature
-55
Package Body temperature
Humidity non-condensing
Moisture Sensitive Level (MSL)
www.ams.com
5
3
Represents a maximum floor time of 168h
Revision 1.0
5 - 33
AS5045B
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6 Electrical Characteristics
TAMB = -40 to +125ºC, VDD5V = 3.0-3.6V (3V operation) VDD5V = 4.5-5.5V (5V operation) unless otherwise noted. Also valid for version I.
Table 3. Electrical Characteristics
Symbol
Parameter
Condition
Min
TAMB
Ambient temperature
Version I
-40
Isupp
Supply current
VDD5V
Supply voltage at pin VDD5V
Typ
Max
Unit
+125
ºC
16
21
mA
4.5
5.0
5.5
3.0
3.3
3.6
3.0
3.3
3.6
3.0
3.3
3.6
1,37
2.2
2.9
1.08
1.9
2.6
Operating Conditions
VDD3V3
Voltage regulator output voltage at pin
VDD3V3
5V Operation
VDD5V
Supply voltage at pin VDD5V
VDD3V3
Supply voltage at pin VDD3V3
3.3V Operation
(pin VDD5V and VDD3V3 connected)
VON
Power-on reset thresholds
On voltage; 300mV typ. hysteresis
Power-on reset thresholds
Off voltage; 300mV typ. hysteresis
Voff
DC supply voltage 3.3V (VDD3V3)
V
V
V
Programming Conditions
VPROG
Programming voltage
Voltage applied during programming
3.3
3.6
V
VProgOff
Programming voltage off level
Line must be discharged to this level
0
1
V
IPROG
Programming current
Current during programming
100
mA
Rprogramme Programmed fuse resistance (log 1)
10µA max. current @ 100mV
100k
∞
Ω
Unprogrammed fuse resistance (log
0)
2mA max. current @ 100mV
50
100
Ω
d
Runprogram
med
DC Characteristics CMOS Schmitt-Trigger Inputs: CLK, CSn (CSn = Internal Pull-up)
0.7 *
VDD5V
VIH
High level input voltage
VIL
Low level input voltage
VIon- VIoff
Schmitt Trigger hysteresis
ILEAK
Input leakage current
CLK only
-1
1
IiL
Pull-up low level input current
CSn only, VDD5V: 5.0V
-30
-100
0.7 *
VDD5V
VDD5V
V
3.3
3.6
V
0.3 *
VDD5V
V
100
µA
Normal operation
V
0.3 *
VDD5V
1
V
V
µA
DC Characteristics CMOS / Program Input: PDIO
VIH
High level input voltage
1
VPROG
High level input voltage
VIL
Low level input voltage
IiL
High level input current
During programming
VDD5V: 5.5V
30
DC Characteristics CMOS Output Open Drain: MagINCn, MagDECn
IOZ
Open drain leakage current
1
µA
VOL
Low level output voltage
VSS +
0.4
V
www.ams.com
Revision 1.0
6 - 33
AS5045B
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
Table 3. Electrical Characteristics
Symbol
Parameter
IO
Output current
Condition
Min
Typ
Max
VDD5V: 4.5V
4
VDD5V: 3V
2
Unit
mA
DC Characteristics CMOS Output: PWM
VOH
High level output voltage
VOL
Low level output voltage
IO
Output current
VDD5V –
0.5
V
VSS
+0.4
VDD5V: 4.5V
4
VDD5V: 3V
2
V
mA
DC Characteristics CMOS Output: A, B, Index
VOH
High level output voltage
VOL
Low level output voltage
IO
Output current
VDD5V –
0.5
V
VSS
+0.4
VDD5V: 4.5V
4
VDD5V: 3V
2
V
mA
DC Characteristics Tri-state CMOS Output: DO
VOH
High level output voltage
VOL
Low level output voltage
IO
Output current
IOZ
Tri-state leakage current
VDD5V –
0.5
V
VSS
+0.4
VDD5V: 4.5V
4
VDD5V: 3V
2
1
V
mA
µA
1. Either with 3.3V or 5V supply.
6.1 Magnetic Input Specification
TAMB = -40 to +125°C, VDD5V = 3.0 to 3.6V (3V operation) VDD5V = 4.5 to 5.5V (5V operation) unless otherwise noted. Also valid for version I.
Two-pole cylindrical diametrically magnetized source:
Table 4. Magnetic Input Specification
Symbol
Parameter
Condition
Min
Typ
dmag
Diameter
4
6
tmag
Thickness
Recommended magnet: Ø 6mm x 2.5mm for
cylindrical magnets
Bpk
Magnetic input field amplitude
Required vertical component of the magnetic
field strength on the die’s surface, measured
along a concentric circle with a radius of
1.1mm
Boff
Magnetic offset
fmag_abs
Disp
www.ams.com
Max
mm
2.5
mm
75
mT
Constant magnetic stray field
± 10
mT
Input frequency
(rotational speed of magnet)
153 rpm @ 4096 positions/rev
2.54
Hz
Displacement radius
Max. offset between defined device center
and magnet axis
(see Figure 17)
0.25
mm
Revision 1.0
45
Unit
7 - 33
AS5045B
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
Table 4. Magnetic Input Specification
Symbol
Parameter
Condition
Min
Typ
Ecc
Eccentricity
Eccentricity of magnet center to rotational axis
Recommended magnet material and
temperature drift
NdFeB (Neodymium Iron Boron)
-0.12
SmCo (Samarium Cobalt)
-0.035
Max
Unit
100
µm
%/K
6.2 System Specifications
TAMB = -40 to +125°C, VDD5V = 3.0 to 3.6V (3V operation) VDD5V = 4.5 to 5.5V (5V operation) unless otherwise noted. Also valid for version I.
Table 5. Input Specification
Symbol
Parameter
Condition
RES
Resolution
INLopt
INLtemp
Max
Unit
0.088 deg
12
bit
Integral non-linearity (optimum)
Maximum error with respect to the best line fit.
Centered magnet without calibration, TAMB
=25 ºC.
± 0.5
deg
Integral non-linearity (optimum)
Maximum error with respect to the best line fit.
Centered magnet without calibration,
TAMB = -40 to +125ºC
± 0.9
deg
INL
Integral non-linearity
Best line fit = (Errmax – Errmin) / 2
Over displacement tolerance with 6mm
diameter magnet, without calibration,
TAMB = -40 to +125ºC
± 1.4
deg
DNL
Differential non-linearity
12-bit, no missing codes
± 0.044
deg
TN
Transition noise
1 sigma
0.06
Deg
RMS
tPwrUp
Power-up time
Until status bit OCF = 1
20
ms
tdelay
System propagation delay
absolute output : delay of ADC, DSP
and absolute interface
96
µs
tdelayINC
System propagation delay
incremental output
192
µs
fS
Internal sampling rate for absolute
output
11.46
kHz
CLK/SEL
Read-out frequency
1
MHz
www.ams.com
Min
9.38
Max. clock frequency to read out serial data
Revision 1.0
Typ
10.42
8 - 33
AS5045B
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
Figure 3. Integral and Differential Non-Linearity Example
4095 α 12bit code
4095
Actual curve
2
TN
DNL+1LSB
1
0
Ideal curve
INL
0.09°
2048
2048
0
0°
180°
360 °
α [degrees]
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.
www.ams.com
Revision 1.0
9 - 33
AS5045B
Datasheet - T i m i n g C h a r a c t e r i s t i c s
7 Timing Characteristics
TAMB = -40 to +125 ºC, VDD5V = 3.0 to 3.6V (3V operation) VDD5V = 4.5 to 5.5V (5V operation), unless otherwise noted. Also valid for version I.
Table 6. Timing Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Units
100
ns
Synchronous Serial Interface (SSI)
tDOactive
Data output activated (logic high)
Time between falling edge of CSn and
data output activated
tCLKFE
First data shifted to output register
Time between falling edge of CSn and
first falling edge of CLK
500
ns
TCLK/2
Start of data output
Rising edge of CLK shifts out one bit at a
time
500
ns
tDOvalid
Data output valid
Time between rising edge of CLK and
data output valid
413
ns
tDOtristate
Data output tri-state
After the last bit DO changes back to “tristate”
100
ns
tCSn
Pulse width of CSn
CSn =high; To initiate read-out of next
angular position
500
fCLK
Read-out frequency
Clock frequency to read out serial data
>0
ns
1
MHz
Pulse Width Modulation Output
fPWM
PWM frequency
Signal period = 4098µs ±10% at TAMB
= -40 to +125ºC
220
244
268
Hz
PWMIN
Minimum pulse width
Position 0d; angle 0 degree
0.90
1
1.10
µs
PWMAX
Maximum pulse width
Position 4098d; angle 359.91 degrees
3686
4096
4506
µs
tPROG
Programming time per bit
Time to prog. a single fuse bit
10
20
µs
tCHARGE
Refresh time per bit
Time to charge the cap after tPROG
1
fLOAD
LOAD frequency
Data can be loaded at n x 2µs
500
kHz
fREAD
READ frequency
Read the data from the latch
2.5
MHz
fWRITE
WRITE frequency
Write the data to the latch
2.5
MHz
Programming Conditions
www.ams.com
Revision 1.0
µs
10 - 33
AS5045B
Datasheet - D e t a i l e d D e s c r i p t i o n
8 Detailed Description
The AS5045B 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 AS5045B provides accurate highresolution 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 AS5045B 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 AS5045B is tolerant to
magnet misalignment and magnetic stray fields due to differential measurement technique and Hall sensor conditioning circuitry.
Figure 4. Typical Arrangement of AS5045B and Magnet
8.1 Synchronous Serial Interface (SSI)
Figure 5. Synchronous Serial Interface with Absolute Angular Position Data
TCLK/2
CSn
tCSn
tCLK FE
tCLK FE
1
CLK
D11
DO
D10 D9
D8
D7
D6
D5
1
18
8
D4
D3
D2
D1
D0
OCF COF
LIN
Mag Mag Even
INC DEC PAR
D11
tDO valid
tDO active
www.ams.com
Angular Position Data
Status Bits
Revision 1.0
tDO Tristate
11 - 33
AS5045B
Datasheet - D e t a i l e d D e s c r i p t i o n
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.
Data Content
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 D11:D0 is invalid. The
absolute output maintains the last valid angular value.
This alarm can 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 D11:D0 can still be used, but can contain invalid data. This warning can 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
1
LIN
0
Mag INC
Mag DEC
0
0
0
1
1
0
1
1
0
Parity
Even checksum of bits
1:15
Note: MagInc=MagDec=1 is only recommended in YELLOW mode (see Table 8)
Z-axis Range Indication (Push Button Feature, Red/Yellow/Green Indicator). The AS5045B 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).
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
Status Bits
Hardware Pins
OTP: Mag CompEn = 1 (Red-Yellow-Green)
Mac INCn Mag DECn
Description
Mac
INC
Mag DEC
LIN
0
0
0
Off
Off
No distance change
Magnetic input field OK (GREEN range, ~45…75mT)
1
1
0
On
Off
YELLOW range: magnetic field is ~ 25…45mT or ~75…135mT. The
AS5045B can still be operated in this range, but with slightly reduced
accuracy.
1
1
1
On
On
RED range: magnetic field is ~<25mT or >~135mT. It is still possible to
operate the AS5045B in the red range, but not recommended.
n/a
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.
www.ams.com
Revision 1.0
12 - 33
AS5045B
Datasheet - D e t a i l e d D e s c r i p t i o n
The two pins can 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 Incremental Mode
The AS5045B has an internal interpolator block. This function is used if the input magnetic field is to fast and a code position is missing. In this
case an interpolation is done.
Incremental Power-up Lock Option. After power-up, the incremental outputs can optionally be locked or unlocked, depending on the
status of the CSn pin:
ext ≤ 5kΩ ). If Csn is low at power-up,
the incremental outputs (A, B, Index) will be high until the internal offset compensation is finished. This unique state (A=B=Index = high) can
be used as an indicator for the external controller to shorten the waiting time at power-up. Instead of waiting for the specified maximum
power up-time (0), the controller can start requesting data from the AS5045B as soon as the state (A=B=Index = high) is cleared.
CSn = low at power-up: CSn has an internal pull-up resistor and must be externally pulled low ( R
CSn = high or open at power-up: In this mode, the incremental outputs (A, B, Index) will remain at logic high state, until CSn
goes low or a
low pulse is applied at CSn. This mode allows intentional disabling of the incremental outputs until, for example the system microcontroller
is ready to receive data.
Figure 6. Incremental Output
ClockWise
Programmed
Zero Position
Counter ClockWise
A
B
1 LSB
I
3 LSB
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.
www.ams.com
Revision 1.0
13 - 33
AS5045B
Datasheet - D e t a i l e d D e s c r i p t i o n
Figure 7. Hysteresis Window for Incremental Outputs
Incremental
Output
Indication
Hysteresis :
0.35°
X +6
X +5
X +4
X +3
X +2
X +1
X
X
Magnet Position
X +1 X +2 X +3 X +4 X +5 X +6
Clockwise Direction
Counterclockwise Direction
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.
8.3 Daisy Chain Mode
The Daisy Chain mode allows connection of several AS5045Bs in series, while still keeping just one digital input for data transfer (see “Data IN”
in Figure 8). 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 9).
Figure 8. Daisy Chain Hardware Configuration
AS5045B
µC
st
1 Device
Data IN
DO
CSn
PDIO
CLK
AS5045B
2
nd
DO
CSn
Device
PDIO
CLK
AS5045B
last Device
DO
CSn
PDIO
CLK
CLK
CSn
www.ams.com
Revision 1.0
14 - 33
AS5045B
Datasheet - D e t a i l e d D e s c r i p t i o n
Figure 9. Daisy Chain Mode Data Transfer
CSn
tCLK FE
TCLK/2
1
CLK
D11
DO
tDO active
18
8
D10
tDO valid
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
OCF COF
LIN
Mag Mag Even
INC DEC PAR
Status Bits
Angular Position Data
D
1
2
3
D11
D10
D9
Angular Position Data
nd
st
2 Device
1 Device
8.4 Pulse Width Modulation (PWM) Output
The AS5045B provides a pulse width modulated output (PWM), whose duty cycle is proportional to the measured angle. For angle position 0 to
4094
t on ⋅ 4098
Position = ------------------------- – 1
( t on + t off )
(EQ 1)
Examples:
1. An angle position of 180° 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 359.8° will generate a pulse width ton = 4095µs and a pause toff of 3 µs resulting in Position = 4094 after the calculation: 4095 * 4098 / (4095 + 3) -1 = 4094
Exception:
1. An angle position of 359.9° will generate a pulse width ton = 4097µs and a pause toff of 1 µs resulting in Position = 4096 after the calculation: 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 10. PWM Output Signal
Angle
PWMIN
0 deg
(Pos 0)
1µs
4098µs
PWMAX
359.91 deg
(Pos 4095)
4097µs
1/fPWM
www.ams.com
Revision 1.0
15 - 33
AS5045B
Datasheet - D e t a i l e d D e s c r i p t i o n
8.4.1
Changing the PWM Frequency
The PWM frequency of the AS5045B can be divided by two by setting a bit (PWMhalfEN) in the OTP register (see Programming the AS5045B on
page 17). With PWMhalfEN = 0 the PWM timing is as shown in Table 9:
Table 9. PWM Signal Parameters (Default mode)
Symbol
Parameter
Typ
Unit
Note
fPWM
PWM frequency
244
Hz
Signal period: 4097µs
PWMIN
MIN pulse width
1
µs
- Position 0d
- Angle 0 deg
PWMAX
MAX pulse width
4097
µs
- Position 4095d
- Angle 359.91 deg
When PWMhalfEN = 1, the PWM timing is as shown in Table 10:
Table 10. PWM Signal Parameters with Half Frequency (OTP option)
Symbol
Parameter
Typ
Unit
Note
fPWM
PWM frequency
122
Hz
Signal period: 8194µs
PWMIN
MIN pulse width
2
µs
- Position 0d
- Angle 0 deg
PWMAX
MAX pulse width
8194
µs
- Position 4095d
- Angle 359.91 deg
8.5 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 AS5045B can be used as direct replacement of potentiometers.
Figure 11. Simple 2nd Order Passive RC Low Pass Filter
Pin12
R2
R1
analog out
PWM
VDD
C1
C2
0V
Pin7
0º
360º
VSS
Figure 10 shows an example of a simple passive low pass filter to generate the analog output.
R1,R2 ≥ 10kΩ
C1,C2 ≥ 2.2µF / 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.
www.ams.com
Revision 1.0
16 - 33
AS5045B
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9 Application Information
The benefits of AS5045B are as follows:
Complete system-on-chip
Flexible system solution provides absolute and PWM outputs simultaneously
Ideal for applications in harsh environments due to contactless position sensing
No calibration required
No temperature compensation necessary
9.1 Programming the AS5045B
After power-on, programming the AS5045B is enabled with the rising edge of CSn with PDIO = high and CLK = low.
The AS5045B 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 (either with 3.3V or 5V supply).
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 pro-
grammed 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 (see Figure 12).
Note: The zero position value can 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.
www.ams.com
Revision 1.0
17 - 33
AS5045B
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9.1.2
OTP Memory Assignment
Symbol
Function
mbit1
Factory Bit 1
51
PWMhalfEN_Index width
PMW frequency Index pulse width
50
MagCompEn
Alarm mode (programmed by ams to 1)
49
pwmDIS
Disable PWM
48
Reserved
47
Reserved
12 bit inc. (programmed by ams)
bit 47 to 1, bit 48 to 0
46
Z0
:
:
35
Z11
34
CCW
33
RA0
:
:
29
RA4
28
FS 0
27
FS 1
26
FS 2
25
FS 3
24
FS 4
23
FS 5
:
:
20
FS 8
19
FS 9
18
FS 10
17
ChipID0
16
ChipID1
:
:
0
ChipID17
12-bit Zero Position
Direction
Factory Bit
18-bit Chip ID
mbit0
9.1.3
Factory Section
Redundancy Address
ID Section
Bit
Customer Section
Table 11. OTP Bit Assignment
Factory Bit 0
User Selectable Settings
The AS5045B 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
- Z [11:0]: Programmable Zero / Index Position
www.ams.com
Revision 1.0
18 - 33
AS5045B
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
- 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
9.1.4
OTP Default Setting
The AS5045B can also be operated without programming. The default, un-programmed setting is:
-
9.1.5
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
Redundancy
For a better programming reliability a redundancy is implemented. In case when the programming of one bit failed this function can be used. With
an address RA(4:0) one bit can be selected and programmed.
0
0
00001
1
0
0
00010
0
1
0
00011
0
0
00100
0
0
Z0
Z1
Z2
Z3
Z4
Z5
Z6
Z7
Z8
Z9
Z10
Z11
CCW
pwmDIS
0
Reserved
MagCompEN
00000
Reserved
Address
PWMhalfEN_Indexwidth
Table 12. Redundancy Addressing
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
00101
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
00110
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
00111
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
01000
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
01001
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
01010
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
01011
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
01100
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
01101
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
01110
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
01111
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
10000
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
10001
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
10010
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
10101
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
www.ams.com
Revision 1.0
19 - 33
AS5045B
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
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.
9.1.7
OTP Register Entry and Exit Condition
For timing options, refer to Programming the AS5045B (page 17).
Figure 12. OTP Access Timing Diagram
OTP Access
Setup Condition
CSn
PDIO
CLK
Exit Condition
Operation Mode Selection
To avoid accidental modification of the OTP during normal operation, each OTP access (Load, Write, Read, Program) requires a defined entry
and exit procedure, using the CSn, PDIO and CLK signals as shown in Figure 12.
www.ams.com
Revision 1.0
20 - 33
AS5045B
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
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 will 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
CSn
2µs
min.
AlignMode enable
Read-out
via SSI
exit AlignMode
Read-out
via SSI
2µs
min.
Figure 14. Exiting Alignment Mode
PDIO
CSn
www.ams.com
Revision 1.0
21 - 33
AS5045B
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9.3 3.3V / 5V Operation
The AS5045B 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) with recommended 2.2µF).
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
2.2 ... 10µF
VDD3V3
VDD3V3
100nF
VDD5V
100nF
LDO
Internal
VDD
VDD5V
LDO
Internal
VDD
DO
DO
4.5 - 5.5V
VSS
I
N
T
E
R
F
A
C
E
PWM
+
-
-
+
CLK
3.0 - 3.6V
CSn
PDIO
VSS
I
N
T
E
R
F
A
C
E
PWM
CLK
CSn
PDIO
A buffer capacitor of 100nF is recommended in both cases close to pin VDD 5V. Note that pin VDD 3V3 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 can lead to larger than normal jitter of the measured
angle.
9.4 Selecting Proper Magnet
Typically the magnet is 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 is verified using a gauss-meter. The magnetic field Bv at a given distance, along a concentric circle with a radius of
1.1mm (R1) is in the range of ±45mT…±75mT(see Figure 16).
www.ams.com
Revision 1.0
22 - 33
AS5045B
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
Figure 16. Typical Magnet (6x3mm) and Magnetic Field Distribution
typ. 6mm diameter
N
S
Magnet axis
Magnet axis
R1
Vertical field
component
R1 concentric circle;
radius 1.1mm
Vertical field
component
Bv
(45…75mT)
0
360
360
9.4.1
Physical Placement of the Magnet
The best linearity can be achieved by placing the center of the magnet exactly over the defined center of the chip as shown in the drawing below:
Figure 17. Defined Chip Center and Magnet Displacement Radius
3.9mm
3.9mm
2.4325mm
1
Defined
center
2.4325mm
Rd
www.ams.com
Area of recommended maximum magnet misalignment
Revision 1.0
23 - 33
AS5045B
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9.4.2
Magnet Placement
The magnet’s center axis must be aligned within a displacement radius Rd of 0.25mm from the defined center of the IC. The magnet can be
placed below or above the device. The distance can be chosen such that the magnetic field on the die surface is within the specified limits (see
Figure 17). The typical distance “z” between the magnet and the package surface is 0.5mm to 1.5mm, provided the use of the recommended
magnet material and dimensions (6mm x 3mm). Larger distances are possible, as long as the required magnetic field strength stays within the
defined limits.
A magnetic field outside the specified range still can be detected by the chip. But the out-of-range condition will be indicated by MagINCn (pin 1)
and MagDECn (pin 2), (see Table 1).
9.5 Failure Diagnostics
The AS5045B also offers several diagnostic and failure detection features:
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 AS5045B 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) must 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 AS5045B, 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 XYmisalignment. 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 2x2mm (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.
www.ams.com
Revision 1.0
24 - 33
AS5045B
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
Figure 18. Example of Linearity Error Over XY Misalignment
6
5
4
° 3
800
500
2
200
1
-100
x
-400
-700
-1000
-1000
-800
-600
y
-400
-200
0
200
400
600
800
1000
0
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.
Figure 19. Example of Linearity Error Over 360º
0.5
0.4
0.3
0.2
transition noise
0.1
Err max
0
-0.1
1
55
109
163
217
271
325
379
433
487
541
595
649
703
757
811
865
919
973
Err min
-0.2
-0.3
-0.4
-0.5
www.ams.com
Revision 1.0
25 - 33
AS5045B
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
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)x1.
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:
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 lowering 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 can be further 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 15,000 rpm and higher).
Note: Statistically, 1 sigma represents 68.27% of readings and 3 sigma represents 99.73% of readings.
9.6.3
High Speed Operation
Sampling Rate:
The AS5045B samples the angular value at a rate of 10.42k samples per second. Consequently, the absolute outputs are
updated each 96µs. At a stationary position of the magnet, the sampling rate creates no additional error.
Absolute Mode: At a sampling rate of 10.4kHz, the number of samples (n) per turn for a magnet rotating at high speed can be calculated by
n=
60 -------------------------rmp ⋅ 96μs
(EQ 3)
The upper speed limit is ~30,000 rpm. The only restriction at high speed is that there will be fewer samples per revolution as the speed
increases (see Table 7). Regardless of the rotational speed, the absolute angular value is always sampled at the highest resolution of 12-bit.
Incremental Mode: Incremental encoders are usually required to produce no missing pulses up to several thousand rpm. Therefore, the
AS5045B has a built-in interpolator, which ensures that there are no missing pulses at the incremental outputs for rotational speeds of up to
15,000 rpm, even at the highest resolution of 12 bits (4096 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.
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 4)
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 AS5045B.
9.6.5
Internal Timing Tolerance
The AS5045B does not require an external ceramic resonator or quartz. All internal clock timings for the AS5045B 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).
- PWM output: A new angular value is updated every 96µs (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 Mod-
www.ams.com
Revision 1.0
26 - 33
AS5045B
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
ulation (PWM) Output on page 15)
9.6.6
Temperature
Magnetic Temperature Coefficient. One of the major benefits of the AS5045B 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 AS5045B automatically
compensates for the varying magnetic field strength over temperature. The magnet’s temperature drift does not need to be considered, as the
AS5045B 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 AS5045B 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 can
increase to less than or equal to ±0.9º due to increasing noise at high temperatures.
Timing Tolerance over Temperature. The internal RC oscillator is factory trimmed to ±5%. Over temperature, this tolerance can 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.
www.ams.com
Revision 1.0
27 - 33
AS5045B
Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s
10 Package Drawings and Markings
The device is available in SSOP 16 (5.3mm x 6.2mm).
Figure 20. Package Drawings and Dimensions
Symbol
A
A1
A2
b
c
D
E
E1
e
L
L1
L2
R
Θ
N
Min
1.73
0.05
1.68
0.22
0.09
5.90
7.40
5.00
0.55
0.09
0º
Nom
1.86
0.13
1.73
0.315
0.17
6.20
7.80
5.30
0.65 BSC
0.75
1.25 REF
0.25 BSC
4º
16
Max
1.99
0.21
1.78
0.38
0.25
6.50
8.20
5.60
0.95
8º
Notes:
1. Dimensions and tolerancing conform to ASME Y14.5M-1994.
2. All dimensions are in millimeters. Angles are in degrees.
Marking: YYWWMZZ.
YY
WW
M
ZZ
Last two digits of the manufacturing year
Manufacturing week
Plant identifier
Assembly traceability code
www.ams.com
Revision 1.0
28 - 33
AS5045B
Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s
Figure 21. Vertical Cross Section of SSOP-16
Notes:
1. All dimensions in mm.
www.ams.com
Revision 1.0
29 - 33
AS5045B
Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s
10.1 Recommended PCB Footprint
Figure 22. PCB Footprint
Recommended Footprint Data
Symbol
mm
A
9.02
B
6.16
C
0.46
D
0.65
E
5.01
www.ams.com
Revision 1.0
30 - 33
AS5045B
Datasheet - R e v i s i o n H i s t o r y
Revision History
Revision
Date
Owner
Description
1.0
03 July, 2013
mub
Initial Revision
www.ams.com
Revision 1.0
31 - 33
AS5045B
Datasheet - O r d e r i n g I n f o r m a t i o n
11 Ordering Information
The devices are available as the standard products shown in Table 13.
Table 13. Ordering Information
Ordering Code
Description
Delivery Form
AS5045B-ASST
Pre-programmed 12-bit incremental (125 °C)
Tape&Reel (13”)
AS5045B-ASSM
Pre-programmed 12-bit incremental (125 °C)
Tape&Reel (7”)
Package
SSOP 16 (5.3mm x 6.2mm)
Note: All products are RoHS compliant and ams green.
Buy our products or get free samples online at www.ams.com/ICdirect
Technical Support is available at www.ams.com/Technical-Support
For further information and requests, email us at sales@ams.com
(or) find your local distributor at www.ams.com/distributor
www.ams.com
Revision 1.0
32 - 33
AS5045B
Datasheet - C o p y r i g h t s
Copyrights
Copyright © 1997-2013, ams 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 ams AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. ams 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. ams 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 ams 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 ams 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.
The information furnished here by ams AG is believed to be correct and accurate. However, ams AG shall not be liable to recipient or any third
party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or
indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the
technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of ams AG rendering of technical or other
services.
Contact Information
Headquarters
ams AG
Tobelbaderstrasse 30
A-8141 Unterpremstaetten, Austria
Tel
Fax
: +43 (0) 3136 500 0
: +43 (0) 3136 525 01
For Sales Offices, Distributors and Representatives, please visit:
http://www.ams.com/contact
www.ams.com
Revision 1.0
33 - 33