PM4314 QDSX
DATA SHEET
PMC-950857
ISSUE 5
QUAD T1/E1 LINE INTERFACE DEVICE
In 75Ω E1 mode, the amplitude of a received pulse at the 1:2 line-coupling
transformer's primary can be in the range from 2.6V to 1.1V (depending on the
length of the cable from the signal source). In this mode, the QDSX can receive
signal levels down to a squelching level of 220mV which means that there is
14.0 dB 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 registers (031H, 071H, 0B1H,
and 0F1H) 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
-
SignalType
Turns
R1
R2
Squelch
Ratio
Level at
(Ω ± 1%)
(Ω ± 1%)
(N ± 5%)
Primary
(mVTypical)
CEPT E1
DSX-1
2
2
2
2
357
205
309
0
121
95.3
93
276
220
227
50
Zo=120Ω
Zo=75Ω
Normal
Bridging
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
32
PMC [ PMC-SIERRA, INC ]
