Dual line interface handles multiple standards

The Exar XRT73L02 is a standards-compliant 3.3V two-channel transceiver line interface unit (LIU) for E3, DS3 and STS-1 applications.

The Exar XRT73L02 is a standards-compliant 3.3V two-channel transceiver line interface unit (LIU) for E3, DS3 and STS-1 applications.

The XRT73L02 is the latest entrant, and completes Exar's 3.3V version of its successful XRT7300 transceiver product family.

At 3.3V, Exar now offers a product family spanning single-, dual-, triple- and quadruple-channel devices.

The XRT73L02 is aimed at multiport E3/DS3/STS-1 applications such as digital crossconnect systems, ATM switches, routers, and add/drop multiplexers.

In environments where restricted board space and power dissipation are challenges, the 3.3V LIU product family offers engineers maximum design flexibility for their multi-port applications.

In addition, communication and data networking equipment manufacturers, using these devices, can implement high-speed, high-density WAN interfaces at a lower cost.

The XRT73L02 is compliant with leading industry standards including ITU-T G.775, G.823, and G.824; Bellcore TR-NWT-000499; and ANSI T1.404.

Apart from the standard features, such as, built-in B3ZS/HDB3 encoder/decoder, the XRT73L02 offers a fully integrated equaliser and clock recovery circuit that operates reliably over a wide range of cable lengths.

In addition, the device incorporates an on-chip transmit clock duty-cycle correction circuit to guarantee pulse template compliance without the need for a tightly controlled transmit clock duty cycle.

Each channel of the XRT73L02 can also be configured independently either through hard wire connections (hardware mode) or a 4-pin serial interface (host mode) to operate at any of the three data rates.

The XRT73L02 provides loopback and transmit line monitoring enabling designers to build in redundancy without other external components.

Also, a change of external components is not necessary to support different data rates; it requires only the appropriate reference clock.

The XRT73L02 is capable of operating over coaxial cable at an E3 rate of 34.368Mbit/s, DS3 rate of 44.736Mbit/s, and STS-1 rate of 51.84Mbit/s.

The versatility of the XRT73L02 follows in the footsteps of other EXAR devices.

It provides the essential physical layer elements for any E3, DS3, and STS-1 transmission applications.

The XRT73L02 provides a seamless interface to Exar's jitter attenuators and access control devices such as DS3/E3 framers (XRT72L5x), ATM UNIs (XRT7234, XRT72L7x,), and M13 multiplexer (XRT72L13).

However, it can also interface to other commercially available access control devices.

The XRT73L02 is packaged in an 80-pin TQFP package and operates at the industrial temperature range of -40 to +85C.

An evaluation board is also available to assist with hardware development.

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