AS5040
10Bit 360º Programmable Magnetic
Rotary Encoder
General Description
The AS5040 is a contactless magnetic rotary encoder for
accurate angular measurement over a full turn of 360°. 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 0.35° = 1024
positions per revolution. This digital data is available as a serial
bit stream and as a PWM signal.
Furthermore, a user-programmable incremental output is
available, making the chip suitable for replacement of various
optical encoders.
An internal voltage regulator allows the AS5040 to operate at
either 3.3 V or 5 V supplies.
Ordering Information
and
Content Guide
appear at end of
datasheet.
Figure 1:
Typical Arrangement of AS5040 and Magnet
ams Datasheet
[v2-11] 2015-Nov-20
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AS5040 −
General Description
Key Benefits & Features
The benefits and features of AS5040, 10Bit 360º Programmable
Magnetic Rotary Encoder are listed below:
Figure 2:
Added Value of Using AS5040
Benefits
•
Highest reliability and durability
•
Simple programming
Features
•
Contactless high resolution rotational position encoding
over a full turn of 360 degrees
•
Simple user-programmable resolution, pole pairs and zero
position
•
•
•
•
•
Serial communication interface (SSI)
10-bit pulse width modulated (PWM) output
Quadrature A/B and Index output signal
Step/Direction and Index output signal
3-Phase commutation for brushless DC motors
•
Multiple interfaces
•
Ideal for motor applications
•
Failure diagnostics
•
Easy setup
•
Great flexibility at a huge application
area
•
Fully automotive qualified
•
Small form factor
•
Robust environmental tolerance
•
Rational speeds up to 30,000 rpm
•
Failure detection mode for magnet placement monitoring
and loss of power supply
•
Serial read-out of multiple interconnected devices using
daisy chain mode
•
Push button functionality detects movement of magnet in
Z-axis
•
AEC-Q100, grade 1
•
SSOP 16 (5.3mm x 6.2mm)
•
Wide temperature range: -40°C to 125°C
Applications
AS5040 is ideal for:
•
Industrial applications:
• Contactless rotary position sensing
• Robotics
• Brushless DC motor commutation
• Power tools
•
Automotive applications:
• Steering wheel position sensing
• Gas pedal position sensing
• Transmission gearbox encoder
• Headlight position control
• Power seat position indicator
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ams Datasheet
[v2-11] 2015-Nov-20
AS5040 −
General Description
•
Office equipment: printers, scanners, copiers
•
Replacement of optical encoders
•
Front panel rotary switches
•
Replacement of potentiometers
Block Diagram
The functional blocks of this device are shown below:
Figure 3:
AS5040 Block Diagram
VDDV3V
MagINCn
VDD5V
LDO 3.3V
PWM
Interface
Ang
MagDECn
PWM_LSB
DSP
Hall Array
&
Frontend
Amplifier
Cos
Mag
Absolute
Interface
(SSI)
DO
CSn
CLK
OTP
Register
A_LSB_U
Programming
Parameters
Incremental
Interface
B_Dir_V
Index_W
Prog
ams Datasheet
[v2-11] 2015-Nov-20
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AS5040 −
Pin Assignment
Pin Assignment
Figure 4:
Pin Configuration SSOP16
MagINCn
MagDECn
A_LSB_U
B_Dir_V
NC
Index_W
VSS
Prog
1
2
16
15
VDD5V
VDD3V3
NC
NC
PWM_LSB
CSn
CLK
DO
AS5040
3
4
5
6
7
8
14
13
12
11
10
9
Pin Description
Figure 6
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 4).
Pins 7, 15 and 16 are supply pins, pins 5, 13 and 14 are for
internal use and must not be connected.
Pins 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.
Pins 3, 4 and 6 are the incremental pulse output pins. The
functionality of these pins can be configured through
programming the one-time programmable (OTP) register.
Figure 5:
Pin Assignment for the Different Incremental Output Modes
Output Mode
1.x: quadrature
2.x:step/direction
3.x: commutation
Pin 3
A
LSB
U
Pin 4
B
Direction
V
Pin 6
Index
Index
W
Pin 12
PWM
PWM
LSB
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[v2-11] 2015-Nov-20
AS5040 −
Pin Assignment
Mode 1.x: Quadrature A/B Output
Represents the default quadrature A/B signal mode.
Mode 2.x: Step / Direction Output
Configures pin 3 to deliver up to 512 pulses (up to 1024 state
changes) per revolution. It is equivalent to the LSB (least
significant bit) of the absolute position value. Pin 4 provides the
information of the rotational direction.
Both modes (mode 1.x and mode 2.x) provide an index signal
(1 pulse/revolution) with an adjustable width of one LSB or
three LSB’s.
Mode 3.x: Brushless DC Motor Commutation Mode
In addition to the absolute encoder output over the SSI
interface, this mode provides commutation signals for
brushless DC motors with either one pole pair or two pole pair
rotors. The commutation signals are usually provided by 3
discrete Hall switches, which are no longer required, as the
AS5040 can fulfill two tasks in parallel: absolute encoder + BLDC
motor commutation.
In this mode, pin 12 provides the LSB output instead of the PWM
(Pulse-Width-Modulation) signal.
Pin 8 (Prog) is also used to program the different incremental
interface modes, the incremental resolution and the zero
position into the
OTP.
This pin is also used as digital input to shift serial data through
the device in
Daisy Chain configuration.
Pin 11 Chip Select (CSn; active low) selects a device within a
network of AS5040 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
and
Programming the AS5040.
Pin 12 allows a single wire output of the 10-bit absolute position
value. The value is encoded into a pulse width modulated signal
with 1μs pulse width per step (1μs to 1024μs over a full turn).
By using an external low pass filter, the digital PWM signal is
converted into an analog voltage, allowing a direct
replacement of potentiometers.
Figure 6:
Pin Description SSOP16
Pin
1
2
Symbol
MagINCn
MagDECn
Type
DO_OD
DO_OD
Description
Magnet Field
Magnitude INCrease;
active low, indicates a
distance reduction between the magnet and the device surface.
Magnet Field
Magnitude DECrease;
active low, indicates a
distance increase between the device and the magnet.
ams Datasheet
[v2-11] 2015-Nov-20
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