Linear and Off-Axis
Magnetic Encoder ICs
High resolution
25µm – AS5304
15µm – AS5306
High speed
20m/s – AS5304
12m/s – AS5306
Optical encoder compatible user interface
start & play
General Description
The AS5304 and AS5306 devices are high perfor-
mance fixed resolution encoder options containing
on-chip hall sensor elements and signal processing
for measuring linear and off axis rotary motion.
Due to the fixed resolutions, the AS5304 and AS5306
devices do not require any register configuration by
the host controller at start up or during operation.
The AS5304 and AS5306 devices allow system
designers to develop rotary encoder applications in
mechanical systems where the sensor IC cannot be
mounted at the end of a rotating device (e.g. at hol-
low shafts). Instead, the IC is mounted off-axis under-
neath a multi-pole single strip magnetized ring. Both
devices can also be used in linear encoder applica-
tions where the IC is mounted directly underneath a
single strip linear multi-pole magnet. Communication
to the host controller is made using an index output
and incremental A/B quadrature outputs providing
40 quadrature pulses (160 steps) per magnet pole
period.
Using, for example, a 32pole-pair circular magnetic
ring, the AS5304 and AS5306 can provide a resolu-
tion of 1280 pulses/rev, which is equivalent to 5120
positions/rev or 12,3 bit. The maximum speed at this
configuration is 9375 rpm.
The AS5304 requires a multipole magnet with a pole
pair length of 4mm and the AS5306 requires 2.4mm
pole pair length. A pole pair consists of one magnetic
north and one magnetic south pole with equal length.
The AS5304 and AS5306 are both 5V operating de-
vices available in a small 20-pin TSSOP package and
specified for an operating ambient temperature of
-40° to +125°C.
Key Features
- On-chip automatic gain and offset correction
- High sensitivity: supports as low as 5mT
magnet field amplitudes
- Single track system allows for lower magnet costs
- High magnet to IC air gap tolerance
- High immunity to external magnetic fields
- Magnetic field strength alarm indicator (A0 output)
Applications
Ideal for any high speed linear motion and off-axis
rotation measurement in applications such as:
- Electrical motors
- Linear X-Y-stages
- Rotation knobs
- Industrial drives
Benefits
- Complete system-on-chip
- Lower cost solution compared to traditional
optical encoders
- No register configuration by host at start up
or during operation
- High reliability due to non-contact sensing
- Extended temperature range
- Suitable for the use in harsh environments
- Robust against external magnetic stray fields
www.austriamicrosystems.com
industry@austriamicrosystems.com
©10/2008 by austriamicrosystems AG
Subject to change without notice
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Micro-
controller
DC
5
V
GPIO
Signal
Processing
&
Channel
Amplifier
Hall
Array
&
Frontend
Amplifier
ADC
&
DSP
A/B
Quadrature
Incremental
Interface
&
Index
CO
S
S
IN
AO
Automatic
Gain
Control
SIN
C
OS
B
A
Analog
Output
Index
magnetic
field alarm
AS5304 / AS5306
Device Resolution Magnet Pole
Length
Digital Outputs
(A/B & Index Outputs)
µm mm
AS5304A25 2 Push Pull
AS5304B25 2 Open Drain
AS5306A15 1.2 Push Pull
AS5306B15 1.2 Open Drain
Ordering Guideline
Block Diagram
www.austriamicrosystems.com/linearencoders
