CN8380 Datasheet, PDF (40/91 Pages) Conexant Systems, Inc – integrated quad line interface unit unit for both 1.544 Mbps (T1) and 2.048 Mbps (E1) applications

2.0 Circuit Description
2.4 Transmitter
CN8380
Quad T1/E1 Line Interface
Option E
Option E uses the alternate 1:1.36 transformer, no series protection resistors (Rs),
and no parallel termination (Rt) for T1 applications. In E1 applications, Rt is
included because it is usually required to provide a minimal level of line
impedance matching. Option E is available only in Host Mode and cannot be used
with DSX-1 applications.
Table 2-8. Transmit Termination Option E
Application
Series Resistors
(Rs)
Parallel Termination
(Rt, Ω)
Return Loss
(dB)
E1—75 Ω
None
68.1
–10
E1—120 Ω
None
107.0
–10
T1—I.431
None
None
0
NOTE(S):
1. Alternate transformer (1:1.36 turns ratio)
2. Hardware Mode: Not Applicable
3. Host Mode: ALT_TR = 1, TERM = 0, T_BOOST = 0 [TLIU_CR; addr n2]
2.4.6.2 Output Disable
The transmitter analog outputs, XTIP[n] and XRING[n], are enabled per channel
by pulling the XOE[n] pins low and are three-stated by pulling the XOE[n] pins
high. In Host Mode, the PDN [TLIU_CR; addr n2] register bit also controls the
XTIP[n] and XRING[n] outputs. A device RESET sets the PDN bits, thereby
disabling XTIP[n] and XRING[n]. User software must clear PDN to enable the
transmitter outputs.
In Hardware Mode, the transmitter outputs are disabled while RESET is held
active (low). When RESET is deactivated, XOE[n] controls the transmitter outputs.
If the transmit driver is disabled (XOE[n] = 1), the driver performance monitor
(DPM) is available for monitoring a transmit signal from an external source.
Refer to Section 2.4.7.2, Driver Performance Monitor.
2-18
Conexant
N8380DSA
Advance Information