A S 51 4 5H / AS 5 14 5 A/ A S5 1 45 B
12-Bit Programmable Magnetic Rotary Encoder
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1 General Description
The AS5145 is a contact less magnetic rotary encoder 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.
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.
An internal voltage regulator allows the AS5145 to operate at either
3.3V or 5V supplies.
2 Key Features
Contact less high resolution rotational position encoding over a
full turn of 360 degrees
Two digital 12-bit absolute outputs:
- Serial interface
- Pulse width modulated (PWM) output
Figure 1. AS5145 Automotive Rotary Encoder IC
Three incremental outputs
Quadrature A/B/I (10 or 12 bit) and Index output signal (pre-
programmed versions available AS5145A for 10-bit and
AS5145B for 12-bit)
User programmable zero position
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 AS5145 devices
using Daisy Chain mode
Tolerant to magnet misalignment and gap variations
Wide temperature range: - 40ºC to +150ºC
Fully automotive qualified to AEC-Q100, grade 0
Small Pb-free package: SSOP 16 (5.3mm x 6.2mm)
3 Applications
The device is ideal for industrial applications like contactless rotary
position sensing and robotics; automotive applications like steering
wheel position sensing, transmission gearbox encoder, head light
position control, torque sensing, valve position sensing and
replacement of high end potentiometers.
DSP
Hall Array
&
Frontend
Amplifier
Absolute
Interface
(SSI)
Incremental
Interface
Sin
Cos
Ang
Mag
MagINCn
MagDECn
DO
PWM
CLK
DTEST1_A
DTEST2_B
Mode_Index
PDIO
CSn
PWM
Interface
OTP
Register
VDD5V
VDD3V3
LDO 3.3V
Mux AS5145
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AS5145
Datasheet - Contents
Contents
1 General Description .................................................................................................................................................................. 1
2 Key Features............................................................................................................................................................................. 1
3 Applications............................................................................................................................................................................... 1
4 Pin Assignments ....................................................................................................................................................................... 4
4.1 Pin Descriptions.................................................................................................................................................................................... 4
5 Absolute Maximum Ratings ...................................................................................................................................................... 6
6 Electrical Characteristics........................................................................................................................................................... 7
6.1 Magnetic Input Specification................................................................................................................................................................. 8
6.2 System Specifications .......................................................................................................................................................................... 9
7 Timing Characteristics ............................................................................................................................................................ 11
8 Detailed Description................................................................................................................................................................ 12
8.1 Mode_Index Pin.................................................................................................................................................................................. 12
8.1.1 Synchronous Serial Interface (SSI) ........................................................................................................................................... 13
8.1.2 Incremental Mode ...................................................................................................................................................................... 14
8.1.3 Sync Mode................................................................................................................................................................................. 16
8.1.4 Sin/Cosine Mode ....................................................................................................................................................................... 16
8.1.5 Daisy Chain Mode ..................................................................................................................................................................... 16
8.2 Pulse Width Modulation (PWM) Output.............................................................................................................................................. 17
8.2.1 Changing the PWM Frequency.................................................................................................................................................. 18
8.3 Analog Output..................................................................................................................................................................................... 18
9 Application Information ........................................................................................................................................................... 19
9.1 Programming the AS5145 .................................................................................................................................................................. 19
9.1.1 Zero Position Programming ....................................................................................................................................................... 19
9.1.2 OTP Memory Assignment.......................................................................................................................................................... 20
9.1.3 User Selectable Settings ........................................................................................................................................................... 20
9.1.4 OTP Default Setting................................................................................................................................................................... 21
9.1.5 Redundancy............................................................................................................................................................................... 21
9.1.6 Redundant Programming Option ............................................................................................................................................... 22
9.1.7 OTP Register Entry and Exit Condition ..................................................................................................................................... 22
9.2 Alignment Mode.................................................................................................................................................................................. 23
9.3 3.3V / 5V Operation............................................................................................................................................................................ 24
9.4 Selecting Proper Magnet.................................................................................................................................................................... 24
9.4.1 Physical Placement of the Magnet ............................................................................................................................................ 25
9.4.2 Magnet Placement..................................................................................................................................................................... 26
9.5 Failure Diagnostics............................................................................................................................................................................. 26
9.5.1 Magnetic Field Strength Diagnosis ............................................................................................................................................ 26
9.5.2 Power Supply Failure Detection ................................................................................................................................................ 26
9.6 Angular Output Tolerances................................................................................................................................................................. 26
9.6.1 Accuracy.................................................................................................................................................................................... 26
9.6.2 Transition Noise......................................................................................................................................................................... 28
9.6.3 High Speed Operation ............................................................................................................................................................... 28
9.6.4 Propagation Delays ................................................................................................................................................................... 28
9.6.5 Internal Timing Tolerance .......................................................................................................................................................... 29
9.6.6 Temperature .............................................................................................................................................................................. 29
9.6.7 Accuracy over Temperature ...................................................................................................................................................... 29
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AS5145
Datasheet - Contents
9.7 Differences between AS5145H, AS5145A, AS5145B and AS5145I .................................................................................................. 29
10 Package Drawings and Markings ......................................................................................................................................... 30
10.1 Recommended PCB Footprint.......................................................................................................................................................... 32
11 Ordering Information ............................................................................................................................................................. 35
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AS5145
Datasheet - Pin Assignments
4 Pin Assignments
Figure 2. Pin Assignments (Top Vie w)
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 Pin Type Description
MagINCn 1 Digital output open
drain
Magnet Field Magnitude Increase. Active low. Indicates a distance
reduction between the magnet and the device surface. (see Table 9)
MagDECn 2 Magnet Field Magnitude Decrease. Active low. Indicates a distance
increase between the device and the magnet. (see Table 9)
DTest1_A 3 Digital output Test output in default mode
DTest2_B 4 Test output in default mode
NC 5 - Must be left unconnected
Mode_Index 6 Digital input/output
pull-down
Select between slow (open, low: VSS) and fast (high) mode. Internal pull-
down resistor (10kΩ).
VSS 7 Supply pin Negative Supply Voltage (GND)
PDIO 8 Digital input pull-down
OTP Programming Input and Data Input for Daisy Chain mode. Pin
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
2
3
4
5
6
7
89
10
11
12
13
14
15
161
MagINCn
MagDECn
DTest1_A
DTest2_B
NC
VSS
PDIO DO
CLK
CSn
PWM
NC
NC
VDD3V3
VDD5V
AS5145
Mode_Index
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AS5145
Datasheet - Pin Assignments
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 multi function pins for sync mode, sin/cosine mode and incremental mode.
Pin 6 Mode_Index allows switching between filtered (slow) and unfiltered (fast mode). In incremental mode, the pin changes from input to output
and provides the index pulse information. A change of the Mode during operation is not allowed. The setup must be constant during power up
and during operation.
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 19). This pin is also used as digital input to shift serial data through the
device in Daisy Chain configuration, (see page 14).
Pin 11 Chip Select (CSn; active low) selects a device within a network of AS5145 encoders 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 23) and programming mode (see Programming the AS5145 on page 19).
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.
CLK 10 Digital input, Schmitt-
Trigger input Clock Input of Synchronous Serial Interface; Schmitt-Trigger input
CSn 11
Digital input pull-
down, Schmitt-Trigger
input
Chip Select. Active low. Schmitt-Trigger input, internal pull-up resistor
(50kΩ)
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
Table 1. Pin Descriptions
Pin Name Pin Number Pin Type Description
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AS5145
Datasheet - 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 Section 6 Electrical Characteristics on page 7 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 Comments
Electrical Parameters
DC supply voltage at pin VDD5V -0.3 7 V
DC supply voltage at pin VDD3V3 5 V
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
Electrostatic Discharge
Electrostatic discharge ± 2 kV Norm: JESD22-A114E
Temperature Ranges and Storage Conditions
Storage temperature -55 150 ºC Min -67ºF; Max +302ºF
Package Body temperature 260 ºC
The reflow peak soldering temperature (body
temperature) specified is in accordance with IPC/
JEDEC J-STD-020 “Moisture/Re flow Sensitivity
Classification for Non-Hermetic Solid State Surface
Mount Devices”.
The lead finish for Pb-free leaded packages is matte tin
(100% Sn).
Humidity non-condensing 5 85 %
Moisture Sensitive Level (MSL) 3 Represents a maximum floor time of 168h
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AS5145
Datasheet - 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. Also valid for version I.
Table 3. Electrical Characteristics
Symbol Parameter Condition Min Typ Max Unit
Operating Conditions
TAMB Ambient temperature Version H/A/B -40 +150 ºC
Isupp Supply current 16 21 mA
VDD5V Supply voltage at pin VDD5V
5V Operation
4.5 5.0 5.5
V
VDD3V3 Voltage regulator output voltage at pin
VDD3V3 3.0 3.3 3.6
VDD5V Supply voltage at pin VDD5V 3.3V Operation
(pin VDD5V and VDD3V3 connected)
3.0 3.3 3.6 V
VDD3V3 Supply voltage at pin VDD3V3 3.0 3.3 3.6
VON Power-on reset thresholds
On voltage; 300mV typ. hysteresis
DC supply voltage 3.3V (VDD3V3)
1,37 2.2 2.9 V
Voff Power-on reset thresholds
Off voltage; 300mV typ. hysteresis 1.08 1.9 2.6
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
dProgrammed fuse resistance (log 1) 10µA max. current @ 100mV 100k ∞Ω
Runprogram
med
Unprogrammed fuse resistance (log
0) 2mA max. current @ 100mV 50 100 Ω
DC Characteristics CMOS Schmitt-Tr igger Inputs: CLK, CSn (CSn = Internal Pull-up)
VIH High level input voltage Normal operation 0.7 *
VDD5V V
VIL Low level input voltage 0.3 *
VDD5V V
VIon- VIoff Schmitt Trigger hysteresis 1 V
ILEAK Input leakage current CLK only -1 1 µA
IiL Pull-up low level input current CSn only, VDD5V: 5.0V -30 -100
DC Characteristics CMOS / Program Input: PDIO
VIH High level input voltage 0.7 *
VDD5V VDD5V V
VPROG1High level input voltage During programming 3.3 3.6 V
VIL Low level input voltage 0.3 *
VDD5V V
IiL High level input current VDD5V: 5.5V 30 100 µA
DC Characteristics CMOS Output Open Drain: MagINCn, MagDECn
IOZ Open drain leakage current 1 µA
VOL Low level output voltage VSS +
0.4 V
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AS5145
Datasheet - Electrical Characteristics
6.1 Magnetic Input Specification
TAMB = -40 to +150°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:
IOOutput current VDD5V: 4.5V 4 mA
VDD5V: 3V 2
DC Characteristics CMOS Output: PWM
VOH High level output voltage VDD5V –
0.5 V
VOL Low level output voltage VSS
+0.4 V
IOOutput current VDD5V: 4.5V 4 mA
VDD5V: 3V 2
DC Characteristi cs CMO S Output: A, B, Index
VOH High level output voltage VDD5V –
0.5 V
VOL Low level output voltage VSS
+0.4 V
IOOutput current VDD5V: 4.5V 4 mA
VDD5V: 3V 2
DC Characteristics Tri-state CMOS Output: DO
VOH High level output voltage VDD5V –
0.5 V
VOL Low level output voltage VSS
+0.4 V
IOOutput current VDD5V: 4.5V 4 mA
VDD5V: 3V 2
IOZ Tri-state leakage current 1 µA
1. Either with 3.3V or 5V supply.
Table 4. Magnetic Input Specification
Symbol Parameter Condition Min Typ Max Unit
dmag Diameter Recommended magnet: Ø 6mm x 2.5mm for
cylindrical magnets
46 mm
tmag Thickness 2.5 mm
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
45 75 mT
Boff Magnetic offset Constant magnetic stray field ± 10 mT
Field non-linearity Including offset gradient 5 %
fmag_abs Input frequency
(rotational speed of magnet)
153 rpm @ 4096 positions/rev;
fast mode 2.54 Hz
38 rpm @ 4096 positions/rev; slow mode 0.63
Table 3. Electrical Characteristics
Symbol Parameter Condition Min Typ Max Unit
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AS5145
Datasheet - Electrical Characteristics
6.2 System Specifications
TAMB = -40 to +150°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.
Disp Displacement radius
Max. offset between defined device center
and magnet axis
(see Figure 19)
0.25 mm
Ecc Eccentricity Eccentricity of magnet center to rotational axis 100 µm
Recommended magnet material and
temperature drift
NdFeB (Neodymium Iron Boron) -0.12 %/K
SmCo (Samarium Cobalt) -0.035
Table 5. Input Specification
Symbol Parameter Condition Min Typ Max Unit
RES Resolution 0.088 deg 12 bit
INLopt Integral non-linearity (optimum)
Maximum error with respect to the best line fit.
Centered magnet without calibration, TAMB
=25 ºC.
± 0.5 deg
INLtemp Integral non-linearity (optimum)
Maximum error with respect to the best line fit.
Centered magnet without calibration,
TAMB = -40 to +150ºC
± 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 +150ºC
± 1.4 deg
DNL Differential non-linearity 12-bit, no missing codes ± 0.044 deg
TN Transition noise
1 sigma, fast mode (MODE = 1) 0.06 Deg
RMS
1 sigma, slow mode
(MODE = 0 or open) 0.03
tPwrUp Power-up time
Fast mode (Mode = 1);
Until status bit OCF = 1 20
ms
Slow mode (Mode = 0 or open);
Until OCF = 1 80
tdelay
System propagation delay
absolute output : delay of ADC, DSP
and absolute interface
Fast mode (MODE = 1) 96
µs
Slow mode (MODE = 0 or open) 384
tdelayINC
System propagation delay
incremental output AS5145A and
AS5145B: delay of ADC, DSP and
incremental interface
Only fast mode possible 192 µs
fSInternal sampling rate for absolute
output:
TAMB = 25ºC, slow mode
(MODE=0 or open) 2.48 2.61 2.74
kHz
TAMB = -40 to +150ºC, slow mode (MODE=0
or open) 2.35 2.61 2.87
fSInternal sampling rate for absolute
output
TAMB = 25ºC, fast mode
(MODE = 1) 9.90 10.42 10.94
kHz
TAMB = -40 to +150ºC, fast mode
(MODE=1) 9.38 10.42 11.46
CLK/SEL Read-out frequency Max. clock frequency to read out serial data 1 MHz
Table 4. Magnetic Input Specification
Symbol Parameter Condition Min Typ Max Unit
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AS5145
Datasheet - Electrical Characteristics
Figure 3. Integral and Differential Non-Linearity Example
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.
180° 360
°
0
°
0
512
1023
α
α
10bit code
0
1
2
0.35°
INL
Ideal curve
Actual curve
TN
512
1023
DNL+1LSB
[degrees]
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AS5145
Datasheet - Timing Characteristics
7 Ti ming Characteristics
TAMB = -40 to +150 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
Synchronous Serial Interface (SSI)
tDOactive Data output activated (logic high) Time between falling edge of CSn and
data output activated 100 ns
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 “tri-
state” 100 ns
tCSn Pulse width of CSn CSn =high; To initiate read-out of next
angular position 500 ns
fCLK Read-out frequency Clock frequency to read out serial data >0 1 MHz
Pulse Width Modulation Output
fPWM PWM frequency Signal period = 4098µs ±10% at TAMB
= -40 to +150ºC 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
Programming Conditions
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 1µs
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
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AS5145
Datasheet - Detailed Description
8 Detailed Description
The AS5145 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 AS5145 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 18).
The AS5145 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 AS5145 is tolerant to
magnet misalignment and magnetic stray fields due to differential measurement technique and Hall sensor conditioning circuitry.
Figure 4. Typical Arrangement of AS5145 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.
Setup the Mode pin affects the following parameters:
Note: A change of the Mode during operation is not allowed. The setup must be constant during power up and during operation.
Table 7. 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) 10.42 kHz (96µs)
Transition noise (1 sigma) ≤ 0.03º rms ≤ 0.06º rms
Output delay 384µs 96µs
Maximum speed @ 4096 samples/rev 38 rpm 153 rpm
Maximum speed @ 1024 samples/rev 153 rpm 610 rpm
Maximum speed @ 256 samples/rev 610 rpm 2441 rpm
Maximum speed @ 64 samples/rev 2441 rpm 9766 rpm
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AS5145
Datasheet - Detailed Description
8.1.1 Synchronous Serial Interface (SSI)
Figure 5. Synchronous Serial Interface with Absolute Angular Position Data
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:
Note: MagInc=MagDec=1 is only recommended in YELLOW mode (see Table 9)
Table 8. Status Bit Outputs
OCF COF LIN Mag INC Mag DEC Parity
10 0
00
Even checksum of bits
1:15
01
10
11
CSn
CLK
DO
tDO valid
Angular Position Data
tDO active Status Bits tDO Tristate
tCSn
tCLK FE
tCLK FE
TCLK/2
1
D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 OCF COF LIN Mag
INC
Mag
DEC
Even
PAR
818 1
D11
D10
D11
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AS5145
Datasheet - Detailed Description
Z-axis Range Indication (Push Button Feature, Red/Yellow/Green Indicator). The AS5145 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:
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 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 9).
8.1.2 Incremental Mode
The AS5145 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.
With the OTP bits OutputMd0 and OutputMd1 a specific mode can be selected. For the available pre-programmed incremental versions (10-bit
and 12-bit), these bits are set during test at ams. 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.
Table 9. Magnetic Field Strength Red-Yellow-Green Indicator
Status Bits Hardware Pins OTP: Mag CompEn = 1 (Red-Yellow-Green)
Mac
INC Mag DEC LIN Mac INCn Mag DECn Description
000OffOff No distance change
Magnetic input field OK (GREEN range, ~45…75mT)
110OnOff
YELLOW range: magnetic field is ~ 25…45mT or ~75…135mT. The
AS5145 can still be operated in this range, but with slightly reduced
accuracy.
111OnOn
RED range: magnetic field is ~<25mT or >~135mT. It is still possible to
operate the AS5145 in the red range, but not recommended.
All other combinations n/a n/a Not available
Table 10. Incremental Resolution
Mode Description Output
Md1 Output
Md0 Resolution
DTest1_A
and
DTest2_B
Pulses
Index Width
Default mode
AS5145 function DTEST1_A and
DTEST2_B are not used. The
Mode_Index pin is used for selection of
the decimation rate (low speed/high
speed).
00
10-bit
Incremental
mode
(low DNL)
DTEST1_A and DTEST2_B are used as
A and B signal. In this mode the
Mode_Index Pin is switched from input
to output and will be the Index Pin. The
decimation rate is set to 64 (fast mode)
and cannot be changed from external.
0 1 10 256
1/3
LSB
12-bit
Incremental
mode (high
DNL)
1 0 12 1024
Sync mode In this mode a control signal is switched
to DTEST1_A and DTEST2_B. 11
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AS5145
Datasheet - Detailed Description
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:
CSn = low at power-up: CSn has an internal pull-up resistor and must be externally pulled low ( ). 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 AS5145 as soon as the state (A=B=Index = high) is cleared.
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
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
Rext 5kΩ≤
Mode_Index
D Test2_B
D Test1_A
1 LSB
Programmed
Zero Position
ClockWise
3 LSB
Counter ClockWise
Magnet Position
Hysteresis :
0.35°
X +2
Incremental
Output
Indication
Clock wise Dir ec tion
Counterclockwise Direction
X +4
XX X +2 X +4 X +5X +3X +1
X +1
X +3
X +6
X +5
X +6
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AS5145
Datasheet - 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.
8.1.3 Sync Mode
This mode is used to synchronize the external electronic with the AS5145. 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 a nd DTest2_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.
8.1.4 Sin/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 isn’t available in
the default mode.
8.1.5 Daisy Chain Mode
The Daisy Chain mode allows connection of several AS5145s 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
DTest1_A
DTest1_B
400µs (100µs)
CSn
CSn CSn CSn
CLK CLK CLK
CLK
Data IN
AS5145
1st Device
AS5145
2nd Device AS5145
last Device
µC
DO DO DO
PDIO PDIO PDIO
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AS5145
Datasheet - Detailed Description
Figure 10. Da isy Chain Mode Data Transfer
8.2 Pulse Width Modulation (PWM) Output
The AS5145 provides a pulse width modulated output (PWM), whose duty cycle is proportional to the measured angle. For angle position 0 to
4094
Position = (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 cal-
culation: 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 cal-
culation: 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 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
CSn
CLK
DO
tDO valid Angular Position Data
tDO active Status Bits
tCLK FE
TCLK/2
1
D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 OCF COF LIN Mag
INC
Mag
DEC
Even
PAR
818 D
D11
123
D10 D9
Angular Position Data
1st Device 2nd Device
D10
D11
ton 4098⋅
ton toff
+()
------------------------- 1–
4098µs
4097µs
1/fPWM
PWMAX
PWMIN
359.91 deg
(Pos 4095)
0 deg
(Pos 0)
Angle
1µs
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AS5145
Datasheet - Detailed Description
8.2.1 Changing the PWM Frequency
The PWM frequency of the AS5145 can be divided by two by setting a bit (PWMhalfEN) in the OTP register (see Programming the AS5145 on
page 19). With PWMhalfEN = 0 the PWM timing is as shown in Table 11:
When PWMhalfEN = 1, the PWM timing is as shown in Table 12:
8.3 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 AS5145 can be used as direct replacement of potentiometers.
Figure 12. Simple 2nd Order Passive RC Low Pass Filter
Figure 11 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.
Table 11. 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
Table 12. 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
R1 R2 analog out
Pin12
PWM
Pin7
VSS
C1 C2
VDD
0V
0º 360º
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AS5145
Datasheet - Application Information
9 Application Information
The benefits of AS5145 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 AS5145
After power-on, programming the AS5145 is enabled with the rising edge of CSn with PDIO = high and CLK = low.
The AS5145 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 13).
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.
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AS5145
Datasheet - Application Information
9.1.2 OTP Memory Assignment
9.1.3 User Selectable Settings
The AS5145 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
-Output Md0: Setting this bit enables sync- or 10-bit incremental mode (see Table 10).
-Output Md1: Setting this bit enables sync- or 12-bit incremental mode (see Table 10).
-Z [11:0]: Programmable Zero / Index Position
Table 13. OTP Bit Assignment
Bit Symbol Function
mbit1 Factory Bit 1
51 PWMhalfEN_Index width PMW frequency Index pulse width
Customer Section
50 MagCompEn Alarm mode (programmed by ams to 1)
49 pwmDIS Disable PWM
48 Output Md0 Default, 10-bit inc, 12-bit inc
Sync mode
47 Output Md1
46 Z0
12-bit Zero Position::
35 Z11
34 CCW Direction
33 RA0
Redundancy Address::
29 RA4
28 FS 0
Factory Bit
Factory Section
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
18-bit Chip ID
ID Section
16 ChipID1
::
0 ChipID17
mbit0 Factory Bit 0
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AS5145
Datasheet - Application Information
-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 AS5145 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. 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.
Table 14. Redundancy Addressing
Address
PWMhalfEN_Indexwidth
MagCompEN
pwmDIS
Output Md0
Output Md1
Z0 Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 Z9 Z10 Z11
CCW
00000 000000000000000000
00001 100000000000000000
00010 0 10000000000000000
00011 0 0 1000000000000000
00100 0 0 0 100000000000000
00101 000010000000000000
00110 000001000000000000
00111 000000100000000000
01000 000000010000000000
01001 000000001000000000
01010 000000000100000000
01011 000000000010000000
01100 000000000001000000
01101 000000000000100000
01110 000000000000010000
01111 000000000000001000
10000 000000000000000100
10001 000000000000000010
10010 000000000000000001
10101 111111111111111111
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AS5145
Datasheet - Application Information
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 AS5145 (page 19).
Figure 13. OTP Acce ss Timing Diagram
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 13.
Figure 14. OTP Programming Connection
OTP Access
Setup Condition
Operation Mode Selection Exit Condition
CSn
PDIO
CLK
AS5145 Dem ob oard
2
3
4
5
6
7
89
10
11
12
13
14
15
161MagINCn
MagDECn
DTest1_A
DTest2_B
NC
Mode_ Index
VSS
PDIO DO
CLK
CSn
PWM
NC
NC
VDD3V3
VDD5V
AS5145
IC 1
7
2
3
4
5
6
1
10n 2.2µF
µC
Cap only required for OTP programming
GND
PROG
CSN
DO
CLK
5VUSB
VDD3V3
VSS
+
10µF
2
3
1
GND
VSS
VPROG
3.3 … 4. 6 V
only required for
OTP programming
connect to USB
interface on PC
USB
For programming,
k eep these 6 wires
as short as possible!
max. length = 2 inches (5cm)
22k
3V3
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AS5145
Datasheet - 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 15). 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 15. Enabling the Alignment Mode
Figure 16. Exiting Alignment Mode
PDIO
CSn
AlignMode enable Read-out
via SSI
2µs
min.
2µs
min.
PDIO
CSn
exit AlignMode Read-out
via SSI
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AS5145
Datasheet - Application Information
9.3 3.3V / 5V Operation
The AS5145 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 17).
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 17) 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 17. Connections for 5V / 3.3V Supply V o ltages
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 18).
Internal
VDD
LDO
I
N
T
E
R
F
A
C
E
VSS
VDD5V
VDD3V3
100nF
4.5 - 5.5V
+
-
2.2 ... 10µF
DO
PWM
CLK
CSn
PDIO
Internal
VDD
LDO
I
N
T
E
R
F
A
C
E
VSS
VDD5V
VDD3V3
3.0 - 3.6V
+
-
DO
PWM
CLK
CSn
PDIO
100nF
5V Operation 3.3V Operation
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AS5145
Datasheet - Application Information
Figure 18. Typical Magnet (6x3mm) and Magnetic Field Distribution
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 19. Defined Chip Center and Magnet Displacement Radius
Magnet axis
Vertical field
component
(45…75mT)
0
360
360
Bv
Vertical field
component
R1 concentric circle;
radius 1.1mm
R1
Magnet axis
typ. 6mm diameter
SN
Area of recommended maximum mag-
net misalignment
Defined
center
Rd
3.9mm 3.9mm
2.4325mm
2.4325mm
1
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AS5145
Datasheet - Application Information
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 19). 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 AS5145 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 AS5145 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 9). 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 AS5145, 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 21).
Misalignment of the magnet further reduces the accuracy. Figure 20 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 2x2mm (79x79mil) with a
step size of 100µm.
For each misalignment step, the measurement as shown in Figure 21 is repeated and the accuracy
(Errmax – Errmin)/2 (e.g. 0.25º in Figure 21) is entered as the Z-axis in the 3D-graph.
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AS5145
Datasheet - Application Information
Figure 20. Example of Linearity Error Over XY Misalignment
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 21. Example of Linearity Error Over 360º
-1000
-700
-400
-100
200
500
800
-1000
-800
-600
-400
-200
0
200
400
600
800
1000
0
1
2
3
4
5
6
°
x
y
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
1 55 109 163 217 271 325 379 433 487 541 595 649 703 757 811 865 919 973
transition noise
Err
max
Err
min
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AS5145
Datasheet - Application Information
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 in fast mode (pin MODE = high) and 0.03 degrees rms (1 sigma)x1 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 read-
ings. An averaging of 4 readings will reduce the transition noise by 6dB or 50%, e.g. from 0.03ºrms to 0.015ºrms (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 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 AS5145 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 mag-
net, 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 cal-
culated by
nslowmode = (EQ 3)
nfastmode = (EQ 4)
The upper speed limit in slow mode is ~6,000 rpm and ~30,000 rpm in fast mode. 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
AS5145 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 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 * pr op.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 AS5145.
60
rpm 384()μs⋅
-----------------------------------
60
rmp 96μs⋅
---------------------------
www.ams.com/AS5145 Revision 1.17 29 - 36
AS5145
Datasheet - Application Information
9.6.5 Internal Timing Tolerance
The AS5145 does not require an external ceramic resonator or quartz. All internal clock timings for the AS5145 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 384µs (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. How-
ever, this tolerance can be cancelled by measuring both Ton and Toff and calculating the angle from the duty cycle (see Pulse Width Mod-
ulation (PWM) Output on page 17)
Position = (EQ 6)
9.6.6 Temperature
Magnetic Temperature Coefficient. One of the major benefits of the AS5145 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 AS5145 automatically
compensates for the varying magnetic field strength over temperature. The magnet’s temperature drift does not need to be considered, as the
AS5145 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 AS5145 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.
9.7 Differences between AS5145H, AS5145A and AS5145B
Table 15. Functional Differences
Function AS5145H AS5145A AS5145B
Filtering mode Selectable by customer via
Mode pin (see Table 7) Pre-defined to Fast mode
Mode_Index pin Input. Must be set hard wired on PCB Output Output
Incremental mode setting Default disabled. Can be enabled by customer
via programming
Pre-defined to 2x256 ppr
low-jitter (10-bit) Pre-defined to 2x1024
ppr (12-bit)
Resolution absolute angle
output (PWM and SSI) 12-bit angle
ton 4097⋅
ton toff
+()
------------------------- 1–
www.ams.com/AS5145 Revision 1.17 30 - 36
AS5145
Datasheet - Package Drawings and Markings
10 Package Drawings and Markings
The device is available in SSOP 16 (5.3mm x 6.2mm).
Figure 22. Package Drawings and Dimensions
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 MZZ
Last two digits of the manufacturing year Manufacturing week Plant identifier Assembly traceability code
Symbol Min Nom Max
A 1.73 1.86 1.99
A1 0.05 0.13 0.21
A2 1.68 1.73 1.78
b 0.22 0.315 0.38
c 0.09 0.17 0.25
D 5.90 6.20 6.50
E 7.40 7.80 8.20
E1 5.00 5.30 5.60
e - 0.65 BSC -
L 0.55 0.75 0.95
L1 - 1.25 REF -
L2 - 0.25 BSC -
R0.09 - -
Θ0º 4º 8º
N16
www.ams.com/AS5145 Revision 1.17 33 - 36
AS5145
Datasheet - Revision History
Revision History
Revision Date Owner Description
1.1
May 30, 2008
apg
Changed the temperature to 150ºC across the datasheet.
Jul 23, 2008 Added Key Feature: Fully automotive qualified to AEC-Q100, grade 0
Jul 25, 2008 Changed the values in Table 10 for 10-bit and 12-bit incremental mode
1.2 Aug 24, 2008 rfu
Inserted 10kΩ for pin 6 in Table 1
changed values for fmag_abs in Table 4
Made changes to Incremental Mode on page 14.
Removed quadrature from Figure 6.
Inserted Incremental Output Hysteresis on page 15 and Figure .
Modified the typ value of all in Table 11.
changed the values in equation2 (page 18)
1.3 Aug 27, 2008 rfu
Modified Applications
Removed table Magnetic field strength variation indicator and modified
Table 9 cell headings
1.4
Sep 29, 2008
apg
Changed angle position values in Pulse Width Modulation (PWM) Output
on page 17 and also update Table 6 for the same.
Feb 13, 2009 Changed the value of tDOvalid in Table 6
Feb 16, 2009
Changed the value of PWMIN, PWMAX in Table 6
Updated Figure 14 with 2.2µF capacitor without polarity
Updated Figure 17 with 2.2µF instead of 2.2µF....10µF
Feb 18, 2009 mub
Changed key feature: Added pre-programmed versions available
Removed 10 bit from pin descriptions for pin 12 on page 4
Deleted Min value for tDOvalid in Table 6
updated ordering information
Feb 22, 2009 apg Changed the Max value of tDOvalid in Table 6 to 413
1.5 Jul 15, 2009 rfu
Added “AS5145-I10/AS5145-I12” to the header
Made some sentence corrections and spelling mistakes
1.6 Updated Incremental Mode on page 14 with new information.
1.7 Aug 12, 2009 apg Added a note to the ordering information
1.8 Sep 29, 2009 rfu Updated Figure 13
Added Incremental Power-up Lock Option on page 15
1.9 Nov 05, 2009 apg
Timing Characteristics (page 11) - Updated the parameter ‘PWM
Frequency’ (fPWM)
1.10 Dec 04, 2009 Updated section Internal Timing Tolerance (page 29)
1.11 Jun 16, 2010 mub Updated Table 1, Table 3, Table 6
Jun 25, 2010 apg Updated device header and Ordering Information (page 35)
1.12 Nov 09, 2011 ach Updated maximum rotation speed in incremental mode (see page 28)
1.13 Nov 25, 2011
ekno
Updated MSL in Absolute Maximum Ratings and Package Drawings and
Markings.
1.14 Feb 29, 2012 Updated Figure 23 and carried out sentence structure related changes
across datasheet.
www.ams.com/AS5145 Revision 1.17 34 - 36
AS5145
Datasheet - Revision History
1.15 Jul 23, 2012
mub
Added comparison table (page 29), Updated storage temp. values.
1.16 Oct 16, 2012 Updated Table 5 and ams logos.
1.17 Jul 04, 2013 Ordering Version Tube removed. Figure 4 replaced by new picture.
Revision Date Owner Description
www.ams.com/AS5145 Revision 1.17 35 - 36
AS5145
Datasheet - Ordering Information
11 Ordering Information
The devices are available as the standard products shown in Table 16.
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
Table 16. Ordering Information
Ordering Code Description Delivery Form Package
AS5145H-HSST, -HSSM 12-Bit Programmable Magnetic Rotary Encoder Tape & Reel
SSOP 16 (5.3mm x 6.2mm)AS5145A-HSST, -HSSM Pre-programmed 10-bit incremental Tape & Reel
AS5145B-HSST, -HSSM Pre-programmed 12-bit incremental Tape & Reel
www.ams.com/AS5145 Revision 1.17 36 - 36
AS5145
Datasheet - Copyrights
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.
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