Exar Announces Industry's First Single-Chip Clock Synchronization Receiver

7/31/2002 - Exar Corporation (Nasdaq: EXAR), a leading provider of high-performance, mixed-signal silicon solutions for the worldwide communications infrastructure today added a new device to its innovative product portfolio. The XRT85L61 (centralized clock interface for T1/E1) is a highly integrated single chip Building Integrated Timing Supply (BITS) clock receiver that extracts a stable timing reference for a variety of telecommunications equipment found at a Central Office (CO) installation. Conventional solutions usually require additional discrete components to perform the same functionality. This part also supports the SDH environment where it can be used as part of a Synchronization Supply Unit (SSU).

Network synchronization is critical to ensure that transmission quality is at it highest level. Without proper synchronization, timing slips can occur which can degrade a network's functionality. BITS clocks are used to overcome this condition.

How it works
For many international telecommunications specifications, clocks are divided into different levels (Strata) that ensure network synchronization. The most accurate level is Stratum 1 (usually provided by a cesium-based atomic clock). It is followed by the Stratum 2, 3 and 4 levels. Clock signal distribution is based on a hierarchical structure where timing information is passed down from a master timing source (Stratum 1 or other Primary Reference Source) to slave clocks. The BITS clock (XRT85L61) will extract timing E1, T1 or 64 kbps signal information from a dedicated timing source, and this timing signal becomes the master timing reference for a given network element. "From a single chip, this product provides the critical timing reference needed by networking equipment at a typical CO," said Dr. Roubik Gregorian, executive VP and general manager Communications Division, CTO. "Customers can use our BITS clock receiver in a wide range of equipment, and because of its small silicon footprint (28-lead TSSOP) the device saves valuable board real estate."

Product Details
The XRT85L61 is a fully integrated single-chip solution for T1/E1, or 64 kHz clock synchronization applications. It has several modes of operation that can be grouped in two ways. It can extract a variety of clock and data signals from 64 kHz signals including 64 kHz, 8 kHz and 400 Hz timing as well as 64 kbit/s data. These clock signals are used for network synchronization. Alternatively, it can be used as a T1/E1 receiver. In this application it can extract clock and data at 2.048 and 1.544 Mbit/sec and detect line code violations and AIS. In this mode of operation it also can be used as a T1/E1 receiver and for network synchronization per GR-1244-CORE Section 3.4.1 R3-27.

All standard terminations for T1 and E1 are supported. The device is also compliant with leading specifications including ITU-T G.703 and G.755. The device has an on-chip crystal-less jitter attenuator with 32-bit FIFO that can be enabled or disabled depending on the application and mode of operation.

"Exar's growing product portfolio of timing and interface devices for telecom applications is aimed at giving customers the widest possible selection of physical layer products from one source (spanning T/E to SONET/SDH) for the access and metro segments of the telecommunications market," said Hugh Wright, director of marketing.

Prices, Packages and Availability
Samples of the part are available now, and volume levels will be available in October 2002. The XRT85L61 in a 28-lead TSSOP operates at 3.3V with 5V tolerance over the industrial temperature range. In 1,000 piece quantities, the XRT85L61 is $17.00.

About Exar
Exar Corporation (NASDAQ: EXAR) designs, develops and markets high-performance, analog and mixed-signal silicon solutions for the worldwide communications infrastructure. Leveraging its industry-proven analog design expertise, system-level knowledge and standard CMOS process technologies, Exar provides OEMs innovative, highly integrated ICs that facilitate the transport and aggregation of signals in access, metro and wide area networks. The Company's physical layer silicon solutions address transmission standards such as T/E carrier, ATM and SONET. Additionally, Exar offers ICs for both the serial communications and the video and imaging markets. The Company is based in Fremont, CA, had fiscal 2002 revenues of $55 million, and employs approximately 290 people worldwide. For more information about Exar, visit www.exar.com

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