PM4341AT1XC
DATA SHEET
PMC-900602
ISSUE 7
T1 FRAMER/TRANSCEIVER
The output pulse shape is synthesized digitally with an internal Digital to Analog
(D/A) converter.The converter is updated at eight times the T1 rate with words
stored in a ROM. These words define the output pulse shape.
AMI signalling is created by exciting either the internal TIP or RING DRIVERS
that drive a line-coupling transformer differentially via the TAP and TAN outputs.
This differential driving scheme insures a small positive to negative pulse
imbalance. The drivers, with the step-up transformer, amplify the output pulses
to their final levels. The TIP and RING drivers also supply the high current
capability required to drive the low impedance output load.
The cable length used in the link between the XPLS and the DSX-1 cross-
connect greatly affects the resulting pulse shapes. This is compensated for by
selecting from one of eight different pulse output shapes built into XPLS. For
short line length settings, a small, negative-going spike may be observed on the
falling edge of the DSX-1 pulse.This spike can be filtered out by using the
optional "snubbing" network shown in Figure 11. This snubber network should
not be required when driving longer lines.
The XPLS includes a driver performance monitor to detect nonfunctional links.
Two monitor inputs, PM_TIP and PM_RING, are internally bonded to the XPLS's
own TAP and TAN outputs. If no pulses are detected alternately across the
PM_TIP or PM_RING monitor points for 62 or 63 consecutive TCLKO periods,
the monitored link is declared failed. The exact threshold (62 or 63 pulses)
depends on the line build-out and the pattern of bipolar violations. The XPLS
can be programmed to produce an interrupt whenever the link monitor state
changes.
The XPLS block provides Alarm Indication Signalling (AIS) generation capability
by generating alternating mark signals on the link when the TAIS bit is
programmed high.This is useful when the internal loopback modes are used.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
55
PMC [ PMC-SIERRA, INC ]
