Power-line communications (PLC) has been around for years, but only recently has it come into its own as a popular networking technology. It uses the standard ac power lines either in the utility’s distribution grid or home or business power wiring.
Using existing wiring simplifies connectivity between any devices or systems using ac power, which today is almost everything. High noise levels on all ac lines, though, have limited the number of applications over longer distances with high data rates.
Semitech Semiconductor’s SM2400 IC solves these problems. This multi-standard PLC transceiver based on orthogonal frequency-division multiplexing (OFDM) operates in a wide range of noise-prone Smart Grid environments while addressing the large number of established and evolving standards and proprietary modes.
Regional requirements and differing standards further complicate communications over the already notoriously noisy power grid. The SM2400 uses OFDM to address this challenge. It features a dual-core architecture with a 32-bit RISC controller for the media access controller (MAC) and physical-layer (PHY) functions and a 32-bit DSP for the PHY OFDM and modulation functions.
The SM2400 essentially is a future-proof PLC solution supporting all common OFDM-based standards including IEEE 1901.2, G3-PLC, and PRIME. In addition, it is programmable to address standards evolution, new standards, and special proprietary modes.
The device has selectable frequency shift keying (FSK), differential and coherent binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), eight-phase-shift keying (8PSK), and coherent 16-phase quadrature amplitude modulation (16QAM) modulations.
Also, the SM2400 can provide data rates of up to 500 kbits/s. The operational bandwidth on the power line is within the 5- to 500-kHz range and configurable to be compliant with the regulatory bands indentified by CENELEC in Europe, the Federal Communications Commission (FCC) in the U.S., and the Association of Radio Industries and Businesses (ARIB) in Japan.
The SM2400 boasts AES 128 security with unique IDs that can’t be physically cloned. On-chip peripheral I/O includes SPI (slave), UART, I2C for the host interface, and SPI master for external flash. Two additional SPI slaves are provided for metering or other devices. Five general-purpose I/O (GPIOs) and JTAG for debugging are available as interfaces as well.
The SM2400’s fully integrated analog front end (AFE) includes the analog-to-digital converter (ADC), digital-to-analog converter (DAC), programmable gain amplifier (PGA), and two op amps. This ensures a minimum bill of materials (BOM) for most applications, though an external high-voltage line driver and line receiver plus transformer are needed for attachment to the power line (see the figure). The interface connections are differential.
Applications for the SM2400 include advanced metering infrastructure and automated meter reading, street lighting control, smart energy home area networking, home automation, building automation, and other deployments requiring communications over an existing power line. The SM2400 is available now for evaluation and Smart Grid system development.