PM6341 E1XC
DATA SHEET
PMC-910419
ISSUE 8
E1 FRAMER/TRANSCEIVER
9.15 Digital DS-1Transmit Interface (DTIF)
The Digital DS-1 Transmit Interface provides control over the various output
options available on the multifunctional digital transmit pins TDP/TDD and
TDN/TFLG. When configured for dual-rail output, the multifunctional pins
become the TDP and TDN outputs. These outputs can be formatted as either
return-to-zero (RZ) or non-return-to-zero (NRZ) signals and can be updated on
either the rising or falling edge of TCLKO. When the interface is configured for
single-rail output, the multifunctional pins become the TDD and TFLG outputs,
which can be enabled to be updated on either the rising or falling TCLKO edge.
Further, the TFLG output can be enabled to indicate FIFO empty or FIFO full
status.
The DTIF block also provides Alarm Indication Signalling (AIS) generation
capability by generating alternating mark signals on the TDP/TDN outputs, or all-
ones on the TDD output, when the TAISEN bit is set in the Transmit Interface
Configuration register.This is useful when the internal loopback modes are used.
9.16 Analog Pulse Generator (XPLS)
The Analog Pulse Generator function is provided by the Transmit Pulse
Generator block (XPLS) block that converts Non Return to Zero (NRZ) pulses
into Alternate Mark Inversion (AMI) line signals suitable for use in a G.703 2048
kbit/s intra-office environment. The dual-rail NRZ pulses are supplied by the
DJAT block. A logical "1" on the TDP output from DJAT causes a positive pulse
to be transmitted; a similar signal on the TDN output from DJAT causes a
negative pulse to be transmitted. If both TDP and TDN are logical "0" or "1," no
output pulse is transmitted.
The output pulse shape is synthesized digitally with an internal Digital to Analog
(D/A) converter.The converter is updated eight times per 2048 kbit/s period with
words stored in a ROM. These words define the output pulse shape. The ROM
words are ITU-T G.703 2048 kbit/s compatible. If an external circuit different
from that recommended in Figure 10 is used, the pulse generator permits
creation of custom pulse shapes. Refer to the Operations section for details.
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.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
59
PMC [ PMC-SIERRA, INC ]
