DS21448

The DS21448 is a quad-port E1 or T1 line interface unit (LIU) for short-haul and long-haul applications. Itincorporates four independent transmitters and four independent receivers in a single 144-pin PBGA or 128-pin LQFP package.

The transmit drivers generate the necessary G.703 E1 waveshapes in 75 or 120
applications and the DSX-1 orCSU line build-outs of 0dB, -7.5dB, -15dB, and -22.5dB for T1 applications.

The DS21448 has a usable receiver sensitivity of 0 to -43dB for E1 applications and 0 to -36dB for T1 that allows it to operate on 0.63mm (22AWG) cables up to 2.5km (E1) and 6000ft (T1) in length. The user has the option to use internal receive termination, software selectable for 75
, 100
, and 120
applications, or external termination.

The on-board crystal-less jitter attenuator can be placed in either the transmit or the receive data path,and requires only a 2.048MHz MCLK for both E1 and T1 applications (with the option of using a 1.544MHz MCLK in T1 applications).

The DS21448 has diagnostic capabilities such as loopbacks and PRBS pattern generation and detection. 16-bitloop-up and loop-down codes can be generated and detected. A single input pin can power down all transmitters to allow the implementation of hitless protection switching (HPS) for 1+1 redundancy without theuse of relays.

The device can be controlled through an 8-bit parallel port (muxed or nonmuxed) or a serial port, and it canbe used in hardware mode. A standard boundary scan interface supports board-level testing.