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TIDA-00172
Reference Design for an Interface to a Position Encoder with EnDat 2.2
TIDA-00172
Overview
This reference design implements a hardware interface based on the HEIDENHAIN EnDat 2.2 standard for position or rotary encoders. The building blocks include the power supply for the encoder with innovative smart eFuse technology and robust half-duplex RS-485 transceivers including line termination and EMC protection. An auxiliary power supply and logic level interface with adjustable I/O voltage level are provided to connect to subsequent MCUs and MPUs that would run the EnDat 2.2 master protocol stack. This design is fully tested to meet EMC immunity requirements for ESD, fast transient burst and surge according to IEC61800-3.
Features
- Design meets EMC immunity requirements for ESD, fast-transient burst and surge according to IEC61800-3
- High-speed RS-485 transceivers robust to 15-kV ESD immunity
- Wide input (15 to 30 VDC) high-efficiency (>85%) DC/DC power supply configurable from 3.6 V to 14 V (defaulted to 8 V) with 200 mA, low-ripple (<20 mVpp) output
- Protected power supply with innovative eFuse technology to protect against over-current, over-power, over- and under-voltage and disconnect in case of fault
- Option to shut down encoder power supply in case of fault or to save power when no encoder is connected
- Level shifter to support 3.3 V, 2.5 V or 1.8 V I/O interface to processors like Sitara AM4x for EnDat 2.2 master
A fully assembled board has been developed for testing and performance validation only, and is not available for sale.
Design files & products
Design files
Download ready-to-use system files to speed your design process.
TIDU368.PDF (7780 K)
Reference design overview and verified performance test data
TIDR763.PDF (198 K)
Detailed schematic diagram for design layout and components
TIDR764.PDF (209 K)
Complete listing of design components, reference designators, and manufacturers/part numbers
TIDR765.PDF (130 K)
Detailed overview of design layout for component placement
TIDR766.ZIP (2340 K)
Files used for 3D models or 2D drawings of IC components
TIDC478.ZIP (185 K)
Design file that contains information on physical board layer of design PCB
Products
Includes TI products in the design and potential alternatives.
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SN74AVC8T245 — 8-Bit Dual-Supply Bus Transceiver with Configurable Voltage-Level Shifting and 3-State Outputs
Data sheet: PDF | HTMLStart development
Technical documentation
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| Type | Title | Date | ||
|---|---|---|---|---|
| * | Design guide | Interface to EnDat 2.2 Position Encoder Design Guide | May 28, 2014 | |
| Technical article | Designing an EMC-compliant interface to motor position encoders – Part 6 | PDF | HTML | Nov. 20, 2015 | |
| Technical article | Designing an EMC-compliant interface to motor position encoders – Part 3 | PDF | HTML | Sep. 14, 2015 |
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