LIU Supports E1, T1 & J1 3.3V Or 5V Apps

Both short- and long-haul transmissions are supported by a new, E1, T1 or J1 line interface unit (LIU) that comes complete with clock and data recovery and jitter attenuation circuitry. The DS2148 LIU only needs a crystalless 2.048-MHz clock for all three interfaces, with an internal PLL used to convert the clock to 1.544 MHz for 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 3.3V/5V LIU can switch the termination values internally via software, eliminating the need for relays or FET switches. DS2148 comes in 44-lead TQFPs or CABGAs, with the latter to be used to create MCMs that yield four independent channels in a 17 x 17-mm BGA footprint.