PM4341AT1XC
DATA SHEET
PMC-900602
ISSUE 7
T1 FRAMER/TRANSCEIVER
In bridging mode, the T1XC is connected to a monitor jack which bridges across
the line and attenuates the signal levels by 20 dB, so the expected pulse
amplitude at the 1:2 line-coupling transformer's primary should be in the range
from 360mV to 120mV (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 50mV±20% which means that there is 6.0dB margin between the
minimum expected signal level and the minimum receivable signal level, in the
worst case.
The RSLC block provides a squelching circuit, which indicates an alarm when
input pulses are below the squelching level threshold. In this state, data is not
sliced, which prevents the detection of noise on an idle transmission line. The
SQ status bit in the RSLC Interrupt Enable/Status register (5DH) goes high
whenever the RSLC block is squelching the input signal. The RSLC can be
configured to generate an interrupt whenever the SQ status bit changes state.
The off-chip attenuator pad network is shown in Figure 6 and the network values
below are recommended for the specified applications:
Table 1
Mode
- Recommended Receive Network Values
Turns Ratio
(N ± 5%)
Squelch
Level at
R1 (Ω ± 1%)
R2 (Ω ± 1%)
Primary (mV
± 20%)
Terminating
Bridging
2
2
309
0
93
227
50
402
Tight tolerances are required on the resistors and turns ratio to meet the return
loss specification.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
37
PMC [ PMC-SIERRA, INC ]
