AS5311
High Resolution Magnetic Linear Encoder
The AS5311 is available in a PB-free TSSOP-20 package and
1 General Description
qualified for an ambient temperature range from -40C to +125C.
The AS5311 is a contactless high resolution magnetic linear encoder
for accurate linear motion and off-axis rotary sensing with a
resolution down to <0.5m. It is a system-on-chip, combining
2 Key Features
integrated Hall elements, analog front end and digital signal
Two 12-bit digital absolute outputs:
processing on a single chip, packaged in a small 20-pin TSSOP
package.
- Serial interface and
A multi-pole magnetic strip or ring with a pole length of 1.0mm is - Pulse width modulated (PWM) output
required to sense the rotational or linear motion. The magnetic strip
Incremental output with Index
is placed above the IC at a distance of typ. 0.3mm.
Red-Yellow-Green indicators monitor magnet placement over
The absolute measurement provides instant indication of the magnet
the chip
position within one pole pair with a resolution of 488nm per step (12-
bit over 2.0mm). This digital data is available as a serial bit stream
3 Applications
and as a PWM signal.
Micro-Actuator feedback
Furthermore, an incremental output is available with a resolution of
1.95m per step. An index pulse is generated once for every pole
Servo drive feedback
pair (once per 2.0mm).The travelling speed in incremental mode is
Robotics
up to 650mm/second.
Replacement of optical encoders
An internal voltage regulator allows the AS5311 to operate at either
3.3 V or 5 V supplies. Depending on the application the AS5311
accepts multi-pole strip magnets as well as multi-pole ring magnets,
both radial and axial magnetized (see Figure 1 and Figure 3).
Figure 1. AS5311 Block Diagram
VDD3V3
MagINCn
MagDECn
VDD5V
LDO 3.3V
PWM
PWM
Interface
Sin Ang
DO
DSP Absolute
Linear Hall
Cos Mag
Interface
Array CSn
(SSI)
&
CLK
Frontend
Amplifier
OTP
Register
A
Incremental
B
Interface
Programming
AS5311
Parameters Index
Prog
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Datasheet - Contents
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 Operating Conditions............................................................................................................................................................................ 6
6.2 DC Characteristics for Digital Inputs and Outputs................................................................................................................................ 6
6.2.1 CMOS Schmitt-Trigger Inputs: CLK, CSn (CSn = internal Pull-up) ............................................................................................. 6
6.2.2 CMOS Output Open Drain: MagINCn, MagDECn ....................................................................................................................... 6
6.2.3 CMOS Output: PWM ................................................................................................................................................................... 6
6.2.4 Tristate CMOS Output: DO.......................................................................................................................................................... 7
6.3 Magnetic Input Specification................................................................................................................................................................. 7
6.4 Electrical System Specifications........................................................................................................................................................... 8
6.5 Timing Characteristics .......................................................................................................................................................................... 9
6.5.1 Pulse Width Modulation Output ................................................................................................................................................... 9
7 Detailed Description................................................................................................................................................................ 10
7.1 Incremental Outputs ........................................................................................................................................................................... 11
7.1.1 Incremental Power-up Lock Option ........................................................................................................................................... 11
7.2 Incremental Output Hysteresis ........................................................................................................................................................... 12
7.3 Synchronous Serial Interface (SSI) .................................................................................................................................................... 12
7.4 Absolute Output Jitter and Hysteresis ................................................................................................................................................ 14
7.4.1 Adding a Digital Hysteresis........................................................................................................................................................ 14
7.4.2 Implementing Digital Filtering .................................................................................................................................................... 14
7.5 Z-axis Range Indication (Red/Yellow/Green Indicator) .................................................................................................................... 14
7.6 Pulse Width Modulation (PWM) Output.............................................................................................................................................. 15
7.7 3.3V / 5V Operation............................................................................................................................................................................ 16
8 Application Information ........................................................................................................................................................... 18
8.1 Magnetization ..................................................................................................................................................................................... 19
8.2 Position of the Index Pulse................................................................................................................................................................. 19
8.3 Mounting the Magnet.......................................................................................................................................................................... 19
8.3.1 Vertical Distance........................................................................................................................................................................ 19
8.3.2 Alignment of Multi-pole Magnet and IC...................................................................................................................................... 20
8.3.3 Lateral Stroke of Multi-pole Strip Magnets................................................................................................................................. 20
8.4 Measurement Data Example.............................................................................................................................................................. 22
8.5 AS5311 Off-axis Rotary Applications.................................................................................................................................................. 23
8.6 Programming the AS5311 .................................................................................................................................................................. 25
8.6.1 Zero Position Programming ....................................................................................................................................................... 25
8.6.2 User Selectable Settings ........................................................................................................................................................... 26
9 Package Drawings and Markings ........................................................................................................................................... 28
9.1 Recommended PCB Footprint............................................................................................................................................................ 29
10 Ordering Information............................................................................................................................................................. 31
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