acquisitionZONE Products for the week of January 12, 2004
Narrowband powerline communication systems typically operate at up to 9.6 kb/s. They use PLMs, which plug into AC power outlets, to enable the transmission of information through electrical power lines, delivering control and automation for various electrical functions and opening new electrical service markets. Agilent's fully integrated powerline DAA chip enables the development of cost-effective PLM network connectivity for both automated meter reading and home network applications. PLMs used in a home network environment allow centralized control and monitoring of home lighting and security systems as well as appliances such as thermostats, motorized entry gates and dishwashers. Narrowband PLMs allow utility companies to automatically and remotely gather information on energy consumption for billing and demand management.
"The HCPL-800J is based on Agilent's state-of-the-art optical isolation technology and is the first in a series of new products that positions Agilent in new markets," said Chong Tze Siong, vice president and general manager of Agilent's Isolation Products Division. "Our new single-chip analog front end has been well received by powerline modem manufacturers. Customers value the device's high level of integration, superior performance and reliability, and they welcome Agilent's high-volume manufacturing and supply chain capability."
The Agilent HCPL-800J interfaces the PLM transceiver/ENDEC (encoder-decoder)
IC with the AC powerline used as the signal transmission medium. It provides
voltage and signal amplification, and galvanic isolation protects the user
and the equipment being interfaced to the PLM. The HCPL-800J incorporates
a control IC and a line IC, optically isolated from each other. The modulated
signal from the PLM transceiver is input to the control IC. This transmit
signal is optically coupled to the line IC, then amplified and sent to the
powerline. In the other direction, a potentially weak and noisy signal from
the powerline is received by the line IC and optically coupled to the control
IC, where it is amplified and output to the PLM transceiver.
analogZONE Says . . .
Agilent is using its optical isolation know-how to great effect here by reducing the front-end of a powerline modem to a single IC with just a few external components being required and, most importantly eliminating the isolation transformer required by previous designs.
The two halves of the IC are the control side (at low potentials) and the line side which interfaces with the ac power line. On the control side is the transmitter LED driver and the diode detector for the receive channel together with a transimpedance amplifier and a gain stage. The signal goes off chip before the gain stage to pass through an external RC filter. On the line side of the IC is the diode detector for the transmit channel with its TIA and the output also goes off chip to go through an external transmit filter. When the signal goes back on chip it passes through a line driver There is also an AGC loop around the TIA to maximize the signal level. A transmit enable is also carried across the barrier and this is detected on the line side for control purposes.
The main receive filter is also off-chip in series with the feed from the ac line.
The expected DIN VDE 0110/1.89 Table 1 classification for the part is I-IV for 110-V mains, and I-III for 220- to 240-V mains. The supply rails to both parts of the IC are nominal 5 V with a control quiescent of 20 mA typical with transmit enabled, and line quiescent of 40 mA typical, also with transmit enabled. That increases linearly with the output current in transmit, reaching 250 mA at 1.4 A p-p output (0.6 A p-p is the highest operational current allowed by load detection circuitry.)
The dynamic characteristics of the part are more than adequate for 9.2 kbit/s communications systems in bandwidth and distortion levels with ASK, FSK or BPSK and should be compatible with any number of such transceivers. Distortion numbers are such that devices using the part should easily pass government radiation targets. AGC response time is 10 µs after the transmit enable goes high and the output signal reaches a typical 66% of steady state after 180 µs.
Protection functions include under-voltage detection, over-temperature shutdown, and a load detection function, which is fundamentally important when dealing with a powerline impedance that varies with the physical point of connection, and over time, and temperature, and loads. An external bi-directional TVS is required across the line to protect the part from power surges and high voltage transients plugging and unplugging a modem.
The HCPL-800J is going to be designed into a lot of powerline modems, making the design of systems for home systems, Internet appliances, meter reading systems, and security systems so much easier.
The HCPL-800J is in production in SOIC-16 and is priced at $2.80 in high-volume quantities.