High EMC Immunity RS485 Interface Reference Design for Tamagawa Encoders


Design files


EMC immunity, especially immunity against inverter switching noise, is important for positioning encoder feedback systems of industrial drives. This design demonstrates a high EMC immunity RS485 transceiver solution which can be used on both the drive and encoder, such as Tamagawa™, EnDat 2.2, BiSS®, and so forth. The design supports a wide input voltage of 5 V. A connector with 3.3-V logic I/O signals and a 3.3-V power supply allows direct interface with the host processor to run the master protocol and power the processor. To meet the supply range of the selected encoder, the design offers an output voltage to the encoder equal to the Vin. This design’s power supply offers protection against overvoltage and short circuit, according to the selected encoder’s voltage range, to prevent damage during a cable short. The design has been tested for up to a 50-m cable length with the Tamagawa encoder.

  • 5-V half-duplex RS485 transceiver with up to 50-Mbps baud rate and improved EMC immunity against IEC61000-4-4
  • Hardware supports 2-wire interfaces standards such as Tamagawa or 4-wire RS485 interface standards like EnDat2.2 and BiSS
  • 5-V supply half-duplex RS485 transceiver THVD1550 with 16kV IEC-ESD and 4kV EFT eliminates cost for external ESD components
  • Highest immunity against IEC61000-4-4 Fast Electrical Transients versus other industry standard RS485 transceivers validated in system tests
  • Designed to meet IEC61800-3 EMC immunity for variable speed drives without the need for additional protection devices such as TVS diodes when used in applications with Encoders using shielded cables
  • The design is in BoosterPack™ Plug-in Module form factor with a connector compatible to the TI LaunchPad™ Development Kit for easy evaluation of Tamagawa with a C2000™ MCU
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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.

TIDUE61.PDF (2443 K)

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

TIDRVX8.ZIP (1452 K)

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

TIDCEK7.ZIP (1575 K)

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

TIDRVX7.PDF (1307 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 RS485 Interface Reference Design Feb. 09, 2018

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