SLLA590 May   2022 THVD8000 , THVD8010

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2THVD80x0 Devices Theory of Operation and Limitations of Use
    1. 2.1 Overview and Similarities between Standard RS-485 Transceivers and THVD80xo Devices
    2. 2.2 Differences between Standard RS-485 Transceivers and THVD8000/8010
    3. 2.3 Standard Approach to Using THVD80xo Devices to Communicate over Power Lines
    4. 2.4 Drawbacks to Standard Approach with Higher Voltage Systems
  5. 3Integration of Line Driver with THVD80x0 Devices to Drive Low Impedance Loads
    1. 3.1 Overcoming Drive Strength Requirement with A Line Driver Amplifier
    2. 3.2 Modification to Typical System Signal Chain Path Through Integration of Line Driver
  6. 4High Voltage Interface and Communication Interface Power Supply
    1. 4.1 Line Driver Output and Input RX signal Protection Circuit
    2. 4.2 High-Voltage Interface
    3. 4.3 Receive Path Optional Bandpass
  7. 5System Level View and Relation to Higher Voltage Implementations
    1. 5.1 Powering the Powerline Communication System
    2. 5.2 System Overview with Selected Test Results
    3. 5.3 Changes to Design for Higher Voltage AC or DC Applications
  8. 6Summary
  9. 7References

1 Introduction

This document will explore how to use the THVD8000/8010 in high voltage applications. First, the THVD8000/8010 basic use will be explained – as this information remains constant across use cases for these devices. Next an explanation of how the integration of a line driver, such as the THS6222, onto the differential bus pins of the THVD8000/8010 will allow the driving of power line loads less than 375 Ω. Then the high voltage interface and the power supply for the communication interface will be shown and what considerations need to be made for this system. Finally, an integrated view of the system with power sources shown as well as the base concept on how to use these ideas to interface with higher than 110 V / 220 V AC and high voltage DC applications with the THVD8000/8010.

Figure 1-1 and Figure 1-2 show two possible architectures for implementing RS-485 communication over low impedance - down to 1 Ω - power lines. Both architectures are independent of powerline voltage as long as the high voltage (HV) interface can isolate the communication lines from the direct power lines of the system.

Figure 1-1, details a block diagram using two separate THVD8000/THVD8010 devices; one device for transmitting data and the other for receiving data.

Figure 1-1 System Implementation 1

This implementation is recommended as it has the most favorable layout since the TX and RX path are inherently different due the line driver; however, with 2 transceivers the BOM cost will increase. Another drawback is that even with two separate transceivers the system still operates in a half-duplex mode.

Figure 1-2 offers an alternative architecture that can reduce BOM cost by only using one THVD8000/THVD8010 device.

Figure 1-2 System Implementation 2

In cost sensitive applications the smaller BOM is ideal. However, this architecture comes with the draw back of a more complicated layout as the driver will have to drive two paths independently of one another – so the engineering effort and design complexity does increase with this implementation with possible reduced performance.