DS2149

4 of 32

1. DETAILED DESCRIPTION

The DS2149 is a complete T1 line interface unit (LIU) for short-haul and long-haul applications. Receive

sensitivity adjusts automatically to the incoming signal and can be limited to -18dB, -26dB, or

-36dB. The device can generate the necessary DSX-1 line build-outs or CSU line build-outs of 0dB,

-7.5dB, -15dB, and -22.5dB. The on-board crystal-less jitter attenuator requires a 1.544MHz reference

clock. The jitter attenuator FIFO is selectable to either 32 bits or 128 bits in depth and can be placed in

either the transmit or receive data paths. The DS2149 has diagnostic capabilities such as loopbacks and

QRSS pattern generation and detection. The device can also generate and detect the in-band loop-up and

loop-down codes specified in AT&T 62411. The device can be configured for control using a serial

interface, or for hardware mode. The device fully meets all of the latest T1 specifications including ANSI

T1.102-1999, ANSI T1.403-1999, ANSI T1.408, and AT&T 62411.

Figure 1-1. Block Diagram

TRING

TTIP

RRING

RTIP

TPOS

TCLK

TNEG

RPOS

RCLK

RNEG

RCL/QPD

NLOOP

Power connections

Hardware Interface

Serial Interface

VCO / PLL