High EMC Immunity RS485 Interface Reference Design for Tamagawa Encoders

1 января 2018

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.

Особенности

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