RS-485 Power Over Bus Reference Design


Design files


This design demonstrates the implementation of a buspowered RS-485 application and allows to evaluate different filters for the DC power. This saves the cost and space for a separate power wiring.

A new preferred approach by using On-off key modulation to transmit RS-485 signals over power line is achieved with THVD8000. By integrating modulation and demodulation circuits, the THVD8000 can increase the frequency content of the baseband data being transmitted. This enables easier DC and AC coupling and system-side interfaces to standard universal asynchronous receivers-transmitters (typically used for RS-485) without any need for special encoding, which is useful in low-data-rate applications. This upgraded approach works well for both DC and AC power without any need for special coding in a microcontroller.

  • Power over Bus for half-duplex RS-485
  • Evaluate different filters
  • One board configurable as master or slave
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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.

TIDU993.PDF (385 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


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


Includes TI products in the design and potential alternatives.

RS-485 & RS-422 transceivers

SN65HVD753.3-V half-duplex RS-485 transceiver with IEC ESD, 20 Mbps

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

SN65HVD825V-Supply RS-485 with IEC ESD Protection

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Design guide RS-485 Power Over Bus Design Guide May 15, 2015

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