DALLAS SEMICONDUCTOR INTRODUCES THE INDUSTRY'S FIRST 3.3V E1/T1/J1 SHORT AND LONG HAUL LINE INTERFACE UNIT
DALLAS, TX-November 2, 1999-Dallas Semiconductor today announced the DS2148 Line Interface Unit (LIU), complete with clock and data recovery and jitter attenuation. The DS2148 supports E1, T1, or J1, 3.3V or 5V, and industrial temperature range, all in one device. E1/T1/J1 interfaces require different peripheral components for clocks and for termination impedances. The DS2148 includes new features that reduce the requirement for these external components when a single design supports all three interfaces.
 All LIUs require a reference clock for the jitter attenuation circuit. The DS2148 only requires a single crystalless 2.048MHz clock for all three interfaces using an internal digital Phase Lock Loop to convert the 2.048MHz clock to 1.544MHz that is used in T1 and J1 applications. E1 requires either a 120-ohm balanced or 75-ohm unbalanced termination while T1 and J1 require a 100-ohm balanced termination on the receive side. The DS2148 offers the ability to switch these termination values internally via software eliminating the need for external relays or FET switches.
Board space is a precious commodity in E1/T1/J1 designs. The DS2148 comes in two standard packages for the single version, 44-TQFP and a 44-CABGA. The CABGA will be used to create a Multi-Chip Module yielding four completely independent channels in a single 17mm X 17mm BGA footprint. This device, available later this quarter, will allow the highest degree of port density without the need to change any software.
Tom Spencer, communications product manager, said "The DS2148 LIU is the perfect solution in E1/T1/J1 designs which either implement the framing function in an FPGA or ASIC or do not require a framing function at all. Many OEMs in Europe still implement their framers in ASICs. Having a low-cost LIU with 3.3V, long haul, and a four-port option gives them a single LIU solution for all applications." The 3.3V capability is critical in line powered applications such as SDSL in Europe and Asia, HDSL2 in North America, or in high density board designs that need to dissipate a lot of heat. The ability to function at 5V is important for retrofitting older systems. The long haul capability eliminates the need to add external line drivers and is selectable in software.
The DS2148 also offers a host of diagnostic capabilities. PRBS generation and detection can be used for loop testing. A 16-bit error counter allows code violations, bipolar violations, excessive zeros, as well as PRBS errors to be counted. The monitor mode offers 20dB, 26dB, and 32dB flat gains for various worldwide monitoring applications. The user has the option to output an n X 2.048MHz clock (n = 1, 2, 4, or 8) synchronous with the received clock to the backplane, which is important for applications using loop timing. 16-bit loop up and loop down codes can be programmed into the DS2148 for automatic network loopback capability.
LIUs can be used as stand-alone components requiring no processor intervention or can be fully configured and monitored using system processors. The DS2148 offers the option for a MUX'd or non-MUX'd parallel port, a serial port, or hardware mode all in one package. This plus the 3.3V/5V and short/long haul capabilities allow a single hardware design to be used in various applications.
The DS2148TN (44-TQFP) and DS2148GN (44-CABGA) are available now. Both devices are available now from stock, priced at $9.00 in quantities of 10,000.
Dallas Semiconductor manufactures a broad line of mixed-signal, specialty semiconductors. The Company combines proprietary fab and circuit technologies to create innovative products that are sold to over 15,000 customers worldwide. Markets served include broadband telecommunications, wireless handsets, cellular base stations, secure Internet communications, networking, servers, data storage and a wide variety of industrial equipment.
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