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