AR49-M25S-B12H

AR49-M49M ABRACON

Document overview

• PDF pages: 18

Technical content

Page 1

Data Sheet

AR49-M49M/M25S Series

Absolute Reflective Encoder Module with Energy-Harvesting Multi-Turn Counter

Description



The Broadcom® AR49 series is an optical absolute encoder module that offers up to 25-bit single-turn (ST) position



information and 24-bit multi-turn (MT) counts, hence a



combined 49-bit high-resolution output. The ST block of the



encoder consists of a patterned disk, a light source, and photosensitive elements to translate the mechanical motion



into an electrical signal. The encoder is designed with a selection of serial communication protocols, with a



dedicated electronic circuit designed for robust signal communication.



Broadcom AR49 series encoders offer many intelligent



features, such as Built-In Temperature Sensor, User Programmable Resolution, Zero Reset, System Alarm, and more. They come with a recommended high-temperature



range of –40°C to 115°C. One of the key advantages is their multi-turn tracking, which employs a proprietary energyharvesting (EH) technology by harvesting the magnetic



energy while the patterned disk with magnet rotates. The



counter ASIC harvests the energy generated by the EH



sensor for processing the rotational count and generates



counting logic to non-volatile memory, which updates and stores the count.

The entire operation of energy generation, counting, and storage processing is completed with limited energy and a short duration; hence, the kit encoder is suited for both lowspeed and high-speed measurement.

Features and Benefits

24-bit energy-harvesting multi-turn and 25-bit optical single-turn Accuracy upon calibration of ±30 arc-seconds Encoder fault and status bits with CRC Integrated differential transceiver for the SSI/BiSS-C/ RS485 communication protocols Single-ended Serial Protocol Interface (SPI 4-wire option) Overall encoder outer diameter of Ø35 mm and maximum height of 17.5 mm 8K bits of user-accessible memory in EEPROM Immediate position detection on power-up; no battery or capacitor required for position detection during a power failure RoHS compliant

Applications

AC/DC servo motor feedback Medical and laboratory equipment Robotics Factory automation

NOTE:

The AR49 series encoders are not halogen-free products.

CAUTION! This product is not specifically designed or

manufactured for use in any specific devices. Customers are solely responsible for determining the suitability of the product for its intended application and solely liable for all loss, damage, expense, or liability in connection with such use. Contact Broadcom for further inquiry.

December 4, 2024

Page 2

Product Specifications

Table 1: Absolute Maximum Ratingsa

a. Exposure to absolute maximum rating conditions for extended periods can affect reliability. Stress greater than the absolute maximum rating can cause permanent damage to the device. b. The maximum junction temperature of the PCB shall not exceed 125°C. c. The encoder works reliably up until this permissible speed. d. A twisted-pair shielded cable is recommended for robustness against environmental noise. Frame ground (FG) termination near the motor frame is recommended.

Table 2: Electrical Characteristics

DC characteristics over the recommended operating conditions of VDD 4.5V to 5.5V, Ta = –40°C to 115°C.

Page 3

Table 3: Mechanical and Environmental Specifications

Mechanical characteristics over the recommended operating conditions of VDD 4.5V to 5.5V, Ta = –40°C to 115°C.

a. Maximum junction temperature of the PCB shall not exceed 125°C. b. Typical values represent the accuracy and repeatability when calibrated with a reference encoder having 10× higher accuracy than the AR49. Reference encoder ≈ 3 arc-seconds.

CAUTION! Refrain from placing the code-wheel magnet or any magnet near the EH sensor on top of the encoder assembly

(maintain a storage condition <20 mT).

Table 4: General Encoder Specifications

Figure 1: Counting Up Direction from Top View

Top View

Page 4

Mechanical Specifications

Package Dimensions – AR49-M49M Series MT Option

Figure 2: MT Encoder Mechanical Dimensions

Horizontal Connector

Vertical Connector

Code-Wheel Assembly

NOTE:

 Dimensions are in millimeters.  Third angle projection.  Motor-shaft outer diameter requirement: 6g6 (–0.004, –0.012) mm.

Page 5

Package Dimensions – AR49-M25S Series ST Option

Figure 3: ST Encoder Mechanical Dimensions

Vertical Connector

Horizontal Connector

Code-Wheel Assembly

NOTE:

 Dimensions are in millimeters.  Third angle projection.  Motor-shaft outer diameter requirement: 6g6 (–0.004, –0.012) mm.

Page 6

Recommended Motor Mounting Dimensions

Figure 4: Mounting Dimensions When Using the Module Outer Diameter (OD) as the Position Guide

Non-ferromagnetic

material

NOTE:

 Dimensions are in millimeters.  Third angle projection.  Use a stainless steel M3 screw to secure the code-wheel–hub assembly to the motor shaft.  Use a screw with pre-applied thread locker.  The motor-shaft end where the code wheel is mounted must be made of non-ferromagnetic material. Recommended motor-shaft material: SUS316L.

Page 7

Figure 5: Mounting Dimensions When Using the Module Inner Diameter (ID) as the Position Guide

Non-ferromagnetic

Material

NOTE:

 Dimensions are in millimeters.  Third angle projection.  Use a stainless steel M3 screw to secure the code-wheel–hub assembly to the motor shaft.  Use a screw with pre-applied thread locker.  The motor-shaft end where the code wheel is mounted must be made of non-ferromagnetic material. Recommended motor-shaft material: SUS316L.

Page 8

Recommended Shield Cover Dimensions

To eliminate or minimize the influence of the external magnetic field interference on encoder operation, use of shielding is

mandatory.

 Shield cover material requirement: Mild steel SPCC-SD, thickness 0.8 mm (minimum).  Finishing: Ni plating 8 μm to 12 μm thick, with Cu undercoating 2 μm to 4 μm.

Figure 6: Reference Shield Cover Design

Encoder Calibration

Broadcom encoders employ an intelligent calibration method by performing auto signal optimization once the encoder is

mounted within assembly tolerances. This eliminates the hassle of mechanically adjusting the encoder position to a very

tight gap and mechanical center. Position accuracy correction is optional and can be carried out with a high-accuracy reference encoder, for example Broadcom’s AR25-AC25 calibration station.

For initial development and early evaluation of the AR49 encoders, the versatile AR49-M49-E01 programming kit can be used to perform the basic encoder configuration and calibration process.

Figure 7: Overview of the AR49 Series Encoder Calibration Flow

Page 9

Interface Protocol

AR49-M49M/M25S-Kxx with RS485 Half-Duplex Protocol

A one-to-one half-duplex serial communication is established between the client encoder and the host (for example, a servo driver). The communication is in a differential transmission format. The encoder will perform specific operations based on the command requests made by the host. Before the encoder executes the requested operation, an acknowledgment of the command request is necessary after first checking the start bit, information data field, and stop bit. If this check fails, the encoder will not acknowledge and execute the received command request.

Figure 8: General Transmission Frames Format on Half-Duplex Line

Data Frames

Transmission Frames Set

Transmission Frame (Host Request)

(Client Encoder Response)

Host Request Frames Set Host

NOTE:

 Start of transmission frames set: Upon detecting the first logic of Low State "0" on the transmission line after an idle state, and if the following three bits conform to the sync code, the encoder will acknowledge it as a valid Request Control Field (RCF), which indicates the start of a transmission frame set. Otherwise, the encoder will continue to search for the next available logic of Low State "0".  End of transmission frames set: After the command frame is detected, if there is no start bit after the end bit of the last frame read, and no subsequent frame is detected, the end of transmission frames set is concluded.  Idle state: The idle state means a space between each transmission frames set and subsequent transmission

frames. At the idle state, the logic of the output in the transmission line is kept to high state "1".

Table 5: RS485 Protocol Specifications

Over the recommended operating conditions of VDD 4.5V to 5.5V, Ta = –40°C to 115°C.

Page 10

RS485 Differential Connection

The recommended I/O connection between the encoder and the host driver has the following basic requirements:

1. Ensure that the encoder power supply, VCC, is within the range of 4.5V to 5.5V. 2. For best noise immunity, use a twisted-pair shielded cable for connection to the servo driver.

1. To prevent undesirable signal reflection, terminate with 220Ω resistors.

1. Terminate the shield-wire to frame ground (FG) at both ends of the communication line.

Figure 9: RS485 Half-Duplex I/O Connection

Encoder

Controller

Page 11

AR49-M49M/M25S-Bxx with BiSS-C Serial Interface

Table 6: BiSS-C Timing Characteristics

Over the recommended operating conditions of VDD 4.5V to 5.5V, Ta = –40°C to 115°C.

Figure 10: BiSS-C Data Field and Interface Timing Diagram

T

MA

CDM(invert)

Tbusy

TBiSS-timeout

MT[23:0]

ST[24:0]

Error[0]

Warning[0] CRC[5:0]

NOTE:

 CRC polynomial = Invert of (X6 + X1 + X0).  The nErr bit is active low. (Combines all the Error Status and reflects in the nErr bit).  The nWar bit is active low. (Combines all the Warning Status and reflects in the nWar bit).  The position data varies depending on the single-turn and multi-turn resolution.

The recommended I/O connection between the encoder and the host driver has the following basic requirements.

Page 12

BiSS-C Full-Duplex Connection

1. Provide the following encoder power supply: – For the 5.0V supply, VCC should be within the range of 4.5V to 5.5V. 2. For best noise immunity, use a twisted-pair shielded cable for connection to the servo driver.

1. To prevent undesirable signal reflection, terminate with 120Ω resistors.

1. Terminate the shield-wire to frame ground (FG) at both ends of the communication line.

Figure 11: BiSS-C Full-Duplex I/O Connection

Page 13

AR49-M49M/M25S-Sxx with SSI 2-Wire Serial Interface

Table 7: SSI Protocol Specifications

Over the recommended operating conditions of VDD 4.5V to 5.5V, Ta = –40°C to 115°C.

Figure 12: SSI Data Field and Timing Diagram

24 bits

25 bits

1 bit

1 bit

For the SSI option, the encoder calibration and device configuration are achieved by switching to the SPI mode during calibration. By toggling the logic levels of the SEL0 and SEL1 pins, the SPI calibration mode can be enabled.

Page 14

SSI 2-Wire Full-Duplex Connection

1. Provide the following encoder power supply: – For the 5.0V supply, VCC should be within the range of 4.5V to 5.5V. 2. For best noise immunity, use a twisted-pair shielded cable for connection to the servo driver.

1. To prevent undesirable signal reflection, terminate with 120Ω resistor.

1. Terminate the shield-wire to frame ground (FG) at both ends of the communication line.

Figure 13: SSI Full-Duplex Connection

Page 15

AR49-M49M/M25S-Pxx with SPI 4-Wire Protocol

Figure 14: SPI Timing Diagram

Table 8: SPI Protocol Specifications

Over the recommended operating conditions of VDD 4.5V to 5.5V, Ta = –40°C to 115°C.

NOTE: The user should read back data to confirm that data has been written successfully.

Page 16

Connector Information

Figure 15: Horizontal and Vertical Connector Information

Horizontal

Vertical

Connector Pin 1

Connector Pin 1

Table 9: Recommended Connector Information

Table 10: Encoder Pinout Description

a. The SSI option is configured via the shared SPI pins and setting the correct logic level for the SEL0 and SEL1 pins. b. For the SSI option, when switching to communicate with the SPI protocol, Pin 3 and Pin 4 of the SPI-NCS and SPI-CLK lines require a strong driver current due to the SSI SCLK+/SCLK- terminating resistor. It is recommended to be achieved with a level shifter or a line driver circuit.

Page 17

Part Numbering

Figure 16: AR49 Module Encoder Part Number Definition

Table 11: Encoder Ordering Information

Table 12: Accessories Ordering Information

Page 18

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