CN8380 Datasheet, PDF (29/91 Pages) Conexant Systems, Inc – integrated quad line interface unit unit for both 1.544 Mbps (T1) and 2.048 Mbps (E1) applications

CN8380
Quad T1/E1 Line Interface
2.3.1.1 Raw Receive
Mode
2.0 Circuit Description
2.3 Receiver
Optionally, the data slicer outputs, before re-timing, can be routed directly to the
RPOSO and RNEGO digital output pins. This option (raw receive mode) is
selected by asserting the RAWMD[n] pin in Hardware Mode or by asserting the
RAWMD register bit [RLIU_CR; addr n1] in Host Mode. In raw receive mode,
RCKO is replaced by the logical OR of the RPOSO and RNEGO output signals.
This mode is useful in applications which provide external clock and data
recovery. Figure 2-4 illustrates the raw mode receiver signals.
Figure 2-4. Raw Mode Receiver Signals
Internal
Equalized
Received
Signal
Data Slicer Level
(50% of Peak)
RPOSO
(RAW Mode)
RNEGO
(RAW Mode)
RCKO
(RAW Mode)
8380_009
BPV
2.3.1.2 Sensitivity
The receiver is capable of recovering signals with cable attenuation in the range of
+3 to –12 dB in E1 and T1 modes. The receiver is configured by setting register
bits appropriately in Host Mode or by setting configuration pins in Hardware
Mode. See Table 2-1for line compatible modes.
Table 2-1. Line Compatible Modes
Mode
Receiver Sensitivity
RALOS
Threshold
Squelch
Threshold
RLOS
Detect
T1
T1/E1 20 dB
Bridge
E1
+3 dB to –12 dB
–17 dB to –26 dB
+3 dB to –12 dB
–18 dB
NA
–18 dB
–18 dB
NA
–18 dB
100 zeros
100 zeros
32 zeros
2.3.1.3 Bridge Mode
In Host Mode, the receiver allows interfacing to network test (MON) points
which are resistively attenuated with resisters in series with transmit and receive
Tip and Ring signals. The Bridge Monitor Level is –20 dB. Bridge operation is
enabled by setting register bit ATTEN [addr n1] to 1. In this mode, RALOS
detection and squelch operation are disabled.
N8380DSA
Conexant
2-7
Advance Information