STMicroelectronics has unwrapped a new power line transceiver, the ST7540, for space constrained and cost-sensitive home and building automation applications and remote monitoring systems.

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The ST7540 is a half duplex binary-FSK transceiver designed for two-way network communication over power lines, with eight selectable carrier frequencies, covering CENELEC bands A, B and C, and four programmable baud rates from 600 to 4800 bps. Reduced in size and pin count, the new ST7540 maintains the field proven ‘core’ technology of the earlier ST7538, but without some accessory functions (such as zero crossing detection and the uncommitted operational amplifier).

Among its new capabilities, the device integrates a single ended power amplifier with accessible input and output lines that can be used with just a few external signal components as part of a tunable active filter for the transmission path, providing superior linear power performances and reducing the application’s parts count and cost.

In addition to the 5 V regulator found on the ST7538, a new on-chip 3.3 V 50 mA voltage regulator, intended for powering different types of external microcontrollers, provides greater design flexibility and further reduces costs.

Other new features include programmable header recognition and frame length count--to increase efficiency and reduce power consumption by activating the external MCU only when a message with a specific header or frame length is detected--and programmable output level freezing, to increase transmission stability in particularly noisy environments. The on-chip available-output-voltage and current loops always allow the transmission levels to be automatically and safely adapted to the line impedance

The ST7540 uses a much smaller and lower pin-count 28-pin package than the state-of the-art ST7538, which will continue to be the basis for highly specialized applications needing auxiliary functions and other features such as zero crossing detection.

The new transceiver enables the design of compact home and building automation, such as easily integrating a complete PLC node in a socket or switch. It is also suitable for "outdoor" applications, such as small street lighting controllers and cost-effective automatic meter reading systems. Its high level of integration, and in particular its new power amplifier topology, significantly reduce the overall BOM cost of such products.

The ST7540 is available now in sample quantities, in the 28-pin HTSSOP28 exposed pad package. Volume pricing will be in the region of $5 in quantities of 1000 pieces.