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

2.1 Overview and Similarities between Standard RS-485 Transceivers and THVD80xo Devices

The THVD8000 and 8010 are RS-485 compliant transceivers that use OOK modulation on the input data to transmit data across a power line. This converts a logic 0 into a pulse train with a pre-selected frequency and a logic 1 into a flat output (V_B – V_A ~0V). Due to this part’s added features the pinout is different from a standard half duplex RS-485 device; a pinout is shown in Figure 2-1 for both devices.

GUID-20220513-SS0I-KXWM-5TBN-VHMZRQ5V87HB-low.png Figure 2-1 THVD80x0 Pinout

The similarities between a standard RS-485 half duplex transceiver and the THVD8000 and THVD8010 parts can be seen in Figure 2-1. Pins 1, 4, 5, and 8 remain similar across most RS-485 devices. Pins 8 and 5 are the power connections to the IC, while pins 1 and 4 are the single ended RX output and TX inputs respectively. The B and A pins are still used for differential communication as in other RS-485 devices and still conform to the 1.5 V differential voltage over a 54 Ω; however, the A/B pins use OOK modulation instead of a typical pulse train used in RS-485.