AS37-H39B Series
39-Bit Battery Backup Multi-Turn Absolute Encoder
Data Sheet
Introduction
The AS37-H39B series encoder is a high-resolution optical
absolute encoder produced by Broadcom®, which offers 23-bit
single-turn and 16-bit multi-turn counts, hence a combined
39-bit high resolution. The AS37-H39B series encoder is a
house encoder consisting of a patterned disk, a light source,
and photosensitive elements to translate the mechanical
motion into electrical signal.
The AS37-H39B series encoder has a built-in communication
protocol that is supported by a full-duplex or half-duplex line
transmissions drive, offering good noise immunity for more
robust transmission of data up to 10 Mb/s in harsh industrial
application. Because the product is intended for industrial
application, ESD protection circuitry has been designed in to
achieve Class 3 ESD immunity per IEC -61000-4-2 standard. The
AS37-H39B series is also compliant with IP40 per IEC 60529
standard.
The key advantage of the AS37-H39B series is multi-turn
tracking employs battery backup technology. It is gearless
multi-turn counting that eliminates the gear wear-out or
acoustics noise issue that is encountered in conventional
geared multi-turn encoder.
Operating Theory
Structures-wise, the encoder contains two main functional
blocks: the single-turn optical engine block and the battery
backup multi-turn counter block. The single-turn engine
comprises the Broadcom developed high-performance optical
detector ASIC, which is accompanied by high-precision
amplifiers circuitry, coupled with a special multi-track code disk
that rotates between the LED emitter and detector IC.
On the multi-turn side, the multi-turn counting is enabled
utilizing battery backup counter technology. During battery
mode (encoder operates in main power OFF state), the battery
backup circuitry periodically powers up the LED emitter and
enables the photo sensor to scan the code disk multi-turn
tracks for detection of shaft rotation. In order to prolong the
battery life, extra effort has been put in the design of the ASIC
to ensure minimum current consumption during battery mode
operation. Therefore, no miscounts occur even in the absence
of external power supply.
Features
39-bit resolution: 16-bit battery backup multi-turn and
23-bit optical single-turn
Built-in communication protocol (option): BiSS C mode, SSI
mode and RS-485 half-duplex
Overall encoder outer diameter Ø37 mm and typical
mounting height 28 mm
Supporting standard hollow taper shaft, short hollow
taper shaft and ¼ inch, 6-mm and 8-mm diameter of the
hollow blind shaft options.
Benefits
High resolution with higher measurement accuracy and
better speed ripple control.
Immediate position detection upon power up without the
need of system homing.
Hollow taper shaft design for China Servo motor market.
Short hollow taper shaft option for low height application.
Small OD and low height for ease of integration to small
size motor.
Applications
Robotics
Factory automation
CNC machine tool
NOTE
Broadcom encoders are not recommended
for use in safety critical applications, e.g., ABS
braking systems, power steering, life support
systems, and critical care medical equipment.
Contact a sales representative if more
clarification is needed.
Broadcom
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