PM4341AT1XC
DATA SHEET
PMC-900602
ISSUE 7
T1 FRAMER/TRANSCEIVER
8
FUNCTIONAL DESCRIPTION
8.1 Digital DS-1 Receive Interface (DRIF)
The Digital DS-1 Receive Interface provides control over the various input options
available on the multifunctional digital receive pins RDP/RDD/SDP and
RDN/RLCV/SDN. When configured for dual-rail input, the multifunctional pins
become the RDP and RDN inputs. These inputs can be enabled to receive either
return-to-zero (RZ) or non-return-to-zero (NRZ) signals; the NRZ input signals can
be sampled on either the rising or falling edge of RCLKI. When the interface is
configured for single-rail input, the multifunctional pins become the RDD and RLCV
inputs, which can be sampled on either the rising or falling RCLKI edge. Finally,
when the analog interface is used, the multifunction pins become the SDP and SDN
outputs, indicating the sliced pulses corresponding to the received positive and
negative analog line pulses.
8.2 Analog DSX-1 Pulse Slicer (RSLC)
The Analog DSX-1 Pulse Slicer function is provided by the RSLC block.The
Receive Data Slicer (RSLC) block provides the first stage of signal conditioning
for a G.703 1544kbit/s serial data stream by converting bipolar line signals to
dual rail RZ pulses. Before an RZ output pulse is generated by the RSLC block,
bipolar input signals must rise to 67% of their peak amplitude. This level is
referred to as the slicing level. The threshold criteria insures accurate pulse or
mark recognition in the presence of noise.
The RSLC block can be disabled by strapping the receive analog power pin,
RAVD to ground. When RLSC is disabled, the T1XC accepts RZ DS1 input
pulses on the RDP/RDD and RDN/RLCV pins.
The RSLC block relies on an external network for compliance to the DSX-1 input
port specifications. The RSLC block is configured via an off-chip attenuator pad
to operate in one of two modes: terminating mode or bridging mode.
According to G.703, the amplitude of a DSX-1 terminating mode received pulse
at the 1:2 line-coupling transformer's primary should be in the range from 3.6V to
1.2V (depending on the length of the cable from the signal source). In this mode,
the T1XC can receive signal levels down to a squelching level of 227mV±20%.
Assuming a worst-case squelching level of 272mV, there is 12.9dB margin
between the minimum expected signal level and the minimum receivable signal
level.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
36
PMC [ PMC-SIERRA, INC ]
