PM4341AT1XC
DATA SHEET
PMC-900602
ISSUE 7
T1 FRAMER/TRANSCEIVER
Note that when DJAT is not being used (e.g. where a 12.352 or 16.384 MHz
XCLK is used), TCLKI must be synchronized with RCLKO for error free
operation of Line Loopback.
DDLB:
The DDLB bit selects the diagnostic digital loopback mode, where the digital
positive and negative RZ pulse outputs from DJAT are internally connected to
the receive positive and negative pulse inputs of CDRC. When DDLB is set to
logic 1, the diagnostic digital loopback mode is enabled. When DDLB is set to
logic 0, the diagnostic digital loopback mode is disabled. If diagnostic digital
loopback is to be used, the TUNI bit must be set to logic 0 in the Transmit
DS1 Interface Configuration register, and the RUNI bit must be set to logic 0
in the Receive DS1 Interface Configuration register.
DMLB:
The DMLB bit enables the diagnostic metallic loopback mode, where the
digital, RZ positive and negative sliced versions of the analog signals output
on the TAP and TAN pins from XPLS are internally connected to the receive
positive and negative pulse inputs of CDRC. Some line build-outs require
large negative pulses in order to satisfy the template at the far end of the line.
However, as DMLB is essentially a zero-line-length loopback, the 0-110’ line
length template should be selected if DMLB is to be used. When DMLB is set
to logic 1, the diagnostic metallic loopback mode is enabled. When DMLB is
set to logic 0, the diagnostic metallic loopback mode is disabled. If diagnostic
metallic loopback is to be used, the TUNI bit must be set to logic 0 in the
Transmit DS1 Interface Configuration register, and the RUNI bit must be set to
logic 0 in the Receive DS1 Interface Configuration register.
TXMFP:
The TXMFP bit introduces a mimic framing pattern in the digital output of the
basic transmitter by forcing a copy of the current framing bit into bit location 1
of the frame, thereby creating a mimic pattern in the bit position immediately
following the correct framing bit. When TXMFP is set to logic 1, the mimic
framing pattern is generated. When TXMFP is set to logic 0, no mimic pattern
is generated.
TXDIS:
The TXDIS bit provides a method of suppressing the output of the basic
transmitter. When TXDIS is set to logic 1, the digital output of XBAS is
disabled by forcing it to logic 0. When TXDIS is set to logic 0, the digital output
of XBAS is not suppressed.
Upon reset of the T1XC, these register bits are cleared to zero.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
89
PMC [ PMC-SIERRA, INC ]
