1 2 - B i t P r o g r a m m a b l e M a g n etic R otary Enco der
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 may 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.
Three incremental outputs
Quadrature A/B (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)
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
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.
Figure 1. AS5145 Automotive Rotary Encoder IC
VDD3V3
VDD5V
MagINCn
MagDECn
PWM
Interface
Sin
Hall Array
&
Front end
Amplifier
Cos
DSP
Ang
Absolute
Interface
(SSI)
DO
CSn
CLK
OTP
Register
Mux
Mode_Index
PDIO
Incremental
Interface
DTEST1_A
DTEST2_B
PWM
LDO 3.3V
Mag
AS5145
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AS5145
Data Sheet - C o n t e n t s
Contents
1 General Description ..................................................................................................................................................................
5 Absolute Maximum Ratings ......................................................................................................................................................
6.1 Magnetic Input Specification.................................................................................................................................................................
6.2 System Specifications ..........................................................................................................................................................................
Synchronous Serial Interface (SSI) ...........................................................................................................................................
8.3 Analog Output.....................................................................................................................................................................................
8.2.1 Changing the PWM Frequency.................................................................................................................................................. 18
9 Application Information ...........................................................................................................................................................
9.1 Programming the AS5145 ..................................................................................................................................................................
9.1.1
9.1.2
9.1.3
9.1.4
9.1.5
9.1.6
9.1.7
19
19
Zero Position Programming ....................................................................................................................................................... 19
User Selectable Settings ........................................................................................................................................................... 20
9.4.1 Physical Placement of the Magnet ............................................................................................................................................ 25
9.6.1 Magnetic Field Strength Diagnosis ............................................................................................................................................ 27
9.6.2 Power Supply Failure Detection ................................................................................................................................................ 27
High Speed Operation ...............................................................................................................................................................
Temperature ..............................................................................................................................................................................
27
27
29
29
29
30
30
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AS5145
Data Sheet - C o n t e n t s
9.7.7 Accuracy over Temperature ...................................................................................................................................................... 30
9.8 AS5145 Differences to AS5045..........................................................................................................................................................
30
10 Package Drawings and Markings .........................................................................................................................................
11 Ordering Information .............................................................................................................................................................
35
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AS5145
Data Sheet - P i n A s s i g n m e n t s
4 Pin Assignments
Figure 2. Pin Assignments (Top View)
MagINCn
MagDECn
DTest1_A
DTest1_B
NC
Mode_Index
VSS
PDIO
1
2
3
16
15
14
VDD5V
VDD3V3
NC
NC
PWM
CSn
CLK
DO
AS5145
4
5
6
7
8
13
12
11
10
9
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 Number
1
2
3
4
5
6
7
8
9
10
11
12
13
Pin Name
MagINCn
MagDECn
DTest1_A
DTest2_B
NC
Mode_Index
V
SS
PDIO
DO
CLK
CSn
PWM
NC
Description
Magnet Field
Magnitude INCrease;
active low, indicates a distance reduction between the
magnet and the device surface.
(see Table 9)
Magnet Field
Magnitude DECrease;
active low, indicates a distance increase between the
device and the magnet.
(see Table 9)
Test output in default mode
Test output in default mode
Must be left unconnected
Select between slow (open, low: V
SS
) and fast (high) mode. Internal pull-down resistor
(~10kΩ).
Negative Supply Voltage (GND)
OTP Programming Input and Data Input for Daisy Chain mode. Internal pull-down resistor
(~74kΩ).
Connect to VSS if not used
Data Output
of
Synchronous Serial Interface
Clock
Input of
Synchronous Serial Interface; Schmitt-Trigger input
Chip Select,
active low; Schmitt-Trigger input, internal pull-up resistor (~50kΩ)
Pulse Width Modulation
of approximately. 244Hz; 1µs/step
(optional 122Hz; 2µs/step)
Must be left unconnected
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AS5145
Data Sheet - P i n A s s i g n m e n t s
Table 1. Pin Descriptions
Pin Number
14
15
16
Pin Name
NC
V
DD
3V3
V
DD
5V
Must be left unconnected
3V-Regulator Output, internally regulated from V
DD
5V. Connect to V
DD
5V for 3V supply
voltage. Do not load externally.
Positive Supply Voltage, 3.0 to 5.5 V
Description
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.
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