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Octal codec increases channel count on analog linecards

Posted: 26 Sep 2002 ?? ?Print Version ?Bookmark and Share

Keywords:legerity? le58083? octal codec? subscriber line circuit? slac?

Legerity Inc. said that their eight-channel voice encoder/decoder will increase the channel density of analog linecards used in broadband digital loop carrier and PBX systems. The modular 3.3V LE58083 octal subscriber line audio circuit can perform the function of eight separate voice codecs/filters, the company said.

"This is another case of getting 10lb. of stuff into a 3lb. sack," said Mike Paquette, GM of Legerity's integrated voice-data products group. "Telecom system makers have stringent space, power and system cost requirements for analog linecards. They like to increase their [analog] line counts from 8 to 16, from 16 to 24 - but the size of the cabinet has not changed."

The octal subscriber line audio circuit (SLAC) hits a density "sweet spot" for high-channel-count linecards, with 24 channels being most common, Paquette said. Legerity's octal SLAC allows a designer to implement a symmetrical design with three SLACs, rather than one 16-channel and one 8-channel device. While some systems implement 32 channels and others implement 64, an 8-channel device remains a "good multiple," he said.

Competitors building 16-channel and 24-channel devices may not include the necessary high-voltage interface in their products, said Kerrie Bellotto, product marketing manager for octal products at Legerity.

A subscriber line interface circuit (SLIC) is ordinarily required to interface a SLAC to the 48V phone loop. One octal SLAC and four Legerity dual SLICs will build one of the highest-density, smallest-footprint analog linecard designs available, Bellotto said.

The LE58083 SLAC comes in a 10-by-10mm BGA package and consumes <33mW per channel. Applications include linecards used in broadband loop carriers, DSL-capable loops, multi-dwelling/multi-tenant telephone concentrators, as well as CO switches and PBX systems.

Legerity believes the market for analog line cards will persist at about 100 million voice lines per year, at a baseline of about $2 per line. Emerging markets like China, India, and Russia will account for new installations, Paquette said. China alone account for 20 million to 30 million linecards a year, he said.

- Stephan Ohr

EE Times

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