High EMC immunity RS-485 interface reference design for absolute encoders


Design files


This high EMC immunity reference design demonstrates a RS-485 transceiver to use on both the drive and within encoders such as: EnDat 2.2, BiSS®, Tamagawa™, etc. EMC immunity, particularly immunity against inverter switching noise, is important for position encoder feedback systems within industrial drives. This design supports a wide input voltage range (used as output voltage to the encoder) from 5 to 15 V (12 V nom) in order to meet the wide supply range of encoders. The power supply of this design includes protection against overvoltage and short circuit according to the selected encoder’s voltage range to prevent damage during a cable short. The BoosterPack™ plug-in module form factor with connector compatible to TI LaunchPad™ development kit is included for easy evaluation of EnDat, BiSS, and other systems with the C2000™ MCU. This reference design has been tested up to 100-m cable length with EnDat 2.2 encoders.

  • 5-V, half-duplex RS-485 transceiver (THVD1550), 50-Mbaud, with 16-kV IEC-ESD and 4-kV EFT eliminates cost for external ESD components
  • Design achieves highest immunity within industry against IEC 61000-4-4 fast electrical transients
  • Supports 4-wire RS-485 interface standards such as EnDat2.2, BiSS or 2-wire interfaces standards such as Tamagawa™
  • Hardware can be used as both a drive and an encoder interface due to configurable clock direction
  • Designed to meet IEC 61800-3 EMC immunity
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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.


Reference design overview and verified performance test data


Detailed schematic diagram for design layout and components


Complete listing of design components, reference designators, and manufacturers/part numbers


Detailed overview of design layout for component placement

TIDRSX1.ZIP (8439 K)

Files used for 3D models or 2D drawings of IC components

TIDCDV9.ZIP (1734 K)

Design file that contains information on physical board layer of design PCB

TIDRSX0.PDF (1302 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Boost converters (integrated switch)

TPS612402.3-V to 5.5-V input range, 3.5-MHz fixed frequency 450-mA boost converter

Data sheet: PDF | HTML
Buck converters (integrated switch)

TPS621623V-17V 1A Step-Down Converters with DCS-Control™

Data sheet: PDF | HTML
Direction-controlled voltage translators

SN74LVC2T452-Bit Dual Supply Transceiver with Configurable Voltage-Level Shifting and 3-State Outputs

Data sheet: PDF | HTML
Load switches

TPS2281018-V, 3-A, 79-mΩ load switch with adj. rise time and adj. output discharge

Data sheet: PDF | HTML
RS-485 & RS-422 transceivers

THVD15505-V RS-485 transceiver with ±18-kV IEC ESD protection

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Design guide High EMC Immunity, RS-485 Interface Reference Design to Absolute Encoders Sep. 27, 2017

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