CN8380 Datasheet, PDF (64/91 Pages) Conexant Systems, Inc – integrated quad line interface unit unit for both 1.544 Mbps (T1) and 2.048 Mbps (E1) applications

3.0 Registers
3.3 Per Channel Registers
CN8380
Quad T1/E1 Line Interface
SQUELCH
Enable Receive Signal Squelch—The digital receiver outputs, RPOSO/RNEGO, are forced to
zero when RALOS is declared. SQUELCH is useful in attached framer applications to allow
the framer to detect LOS during an RALOS condition.
0 = Normal
1 = Squelch RPOSO/RNEGO outputs upon RALOS detect
12, 22, 32, 42 —Transmitter Configuration (TLIU_CR)
7
ALT_TR
6
TERM
5
4
3
2
PDN
T_BOOST
PPT
PULSE[2]
1
PULSE[1]
R/W
0
PULSE[0]
ALT_TR
TERM
PDN
T_BOOST
PPT
Alternate Transformer Select—Adjusts the transmit output level for one of two possible
transmitter transformer turns ratios. Normally, a turns ratio of 1:2 for the transmitter is used.
An alternate transformer with turns ratio of 1:1.36 can be selected to minimize power
dissipation
0 = Normal transformer (1:2)
1 = Alternate transformer (1:1.36)
Transmitter Termination Select—Adjusts the transmit XTIP/XRING output amplitude to
compensate for the presence of an optional external termination resistor. The external resistor
is placed in parallel across XTIP/XRING on systems that must meet transmitter return loss
requirements. Refer to Figure 2-7, Transmit Termination Components, for resistor placement.
Refer to Tables 2-4 through 2-8 for return loss values.
0 = no external transmit termination resistor used
1 = external transmit termination resistor used
Power Down—Unused channels can be put into a low power mode in order to minimize power
dissipation. In low power mode, XTIP/XRING, RPOSO/RNEGO, and RCKO outputs are
three-stated. All other receiver functions are not affected.
0 = Channel is disabled, low power mode
1 = Channel is enabled, normal operation
Transmit Level Boost—Adjusts the transmit output level to compensate for series resistance
added to the output by surge protection circuitry. Typical resistance values are 5.6 ohms in
series with line side XTIP and XRING signals.
0 = No compensation
1 = Compensation enabled
Programmed Pulse Template—Enables custom transmit pulse transmission. The programmed
pulse shape stored in the corresponding shape register, SHAPEn [addr n8 – nF], is used for
transmission.
0 = Pulse template selected by PULSE(2:0)
1 = Programmed pulse template selected
3-12
Conexant
N8380DSA
Advance Information
4/21/99