XRT81L27

Specifications

Specifications
No. ofCH	7
DataRate(s)	E1
Clk Rec	Yes
SH/LH	S
Temp.Range	Ind.
OpPwr Sup/Max Cur	3.3V ±5%, 55mA
Pkgs	TQFP-128

Description



Long established in the E1 arena, Exar proves again, it has the right combination of design expertise, and market knowledge to bring innovative products to market. The XRT82D20 (single-channel), and the XRT81L27 (seven-channel) join several other E1 AFEs and LIUs to give designers a multitude of architecture combinations to meet, or exceed their OEM market requirements.

These XRT81L27 new E1 devices, coupled with an already extensive product line including two seven-channel AFEs (XRT5897 and XRT5997), several four-channel devices (XRT5894, XRT5793, XRT5794 and XRT82L24), plus two single-channel parts (XRT59L91 and XRT7288) give EXAR a distinct marketplace advantage. These new products, along with Exar's other E1 LIUs and AFEs give customers a clear, and rich product family spanning DS1/E1 to SONET/SDH. Applications for these new devices include multiplexers (PDH and SDH), digital cross connects, DECT (Digital European Cordless Telephone) base stations, and CSU/DSU equipment.

The seven-channel (XRT81L27), and single-channel device (XRT82D20) complement Exar's already strong E1 The XRT81L27 contains seven independent E1 channels, including data and clock recovery circuits. Each channel performs the driver and receiver functions necessary to convert bipolar signals to logical levels as well as the reverse. Devices with seven E1 interfaces provide the most efficient method of implementing 21-channel line cards.

The XRT81L27 device offers two distinct modes of Loss of Signal (LOS) detection: 1) The first approach does not require an external clock, but provides an LOS output indication signal that complies with ITU G.775 requirements; 2) the other pproach does invoke an external clock that increases delay of LOS declaration and clearing. This allows the designer to implement LOS specifications that require a greater delay than the G.775 standard.

The XRT82D20 single-channel line interface device supports 75 ohm and 120 ohm E1 applications. XRT81L27 consists of a receiver with adaptive data slicer for accurate data and clock recovery, and a transmitter which accepts either single, or dual-rail digital input for signal line transmission using a low-impedance differential line driver. The XRT82D20 also includes a crystal-less jitter attenuator for clock and data smoothing which can be selected in either the transmit or receive path. The device is a complete line interface unit that allows the physical layer of the system to be implemented without additional components.