![](http://datasheet.mmic.net.cn/370000/T7633_datasheet_16735409/T7633_172.png)
Advance Data Sheet
T7633 Dual T1/E1 3.3 V Short-Haul Terminator
May 1998
162
Lucent Technologies Inc.
Line Interface Control Registers
(continued)
LIU Control Register (LIU_REG4)
LIU Configuration Register (LIU_REG5)
The control bits in the channel configuration register 5 are used to select powerdown mode, AIS generation, and
loopbacks for the LIU. The PWRDN and XLAIS bits are active-high. This is a read/write register. The default value
of this register is 02 (hex).
Loopback Control (from Table 10, page 44)
1. The reset default condition is LOOPA = LOOPB = 0 (no loopback).
2. During the transmit AIS condition, the looped data will be the transmitted data from the framer or system interface and not the all 1s signal.
3. Transmit AIS request is ignored.
Table 85. LIU Register (LIU_REG4) (404, A04)
Bit
Symbol
Description
0
ALTIMER
The ALTIMER bit is used to select the time required to declare ALOS. ALTIMER = 0
selects 1 ms—2.6 ms. ALTIMER = 1 selects 10 bit to 255 bit periods.
The RCVAIS bit selects the shut down function for the receiver during analog loss
of signal alarm (ALOS). RCVAIS operates in conjunction with the LOSSD bit. See
LIU-REG3.
PFLALM prevents the DLOS alarm from occurring during FLLOOP activation.
PFLALM = 1 activates the PFLALM function.
PRLALM prevents the LOTC alarm from occurring during RLOOP activation/deacti-
vation. PRLALM = 1 activates the PRLALM function.
PHIZALM prevents the TDM alarm from occurring when the driver are in a high-
impedance state. PHIZALM = 1 activates the PHIZALM function.
JABW0 = 1 selects the lower bandwidth jitter attenuator option in CEPT mode.
Reserved.
Write to 0.
1
RCVAIS
2
PFLALM
3
PRLALM
4
PHIZALM
5
JABW0
—
6—7
Table 86. LIU Configuration Register (LIU_REG5) (405, A05)
Bit
Symbol
Description
0
1
PWRDN
XLAIS
PWRDN = 1 activates powerdown.
XLAIS = 1 enables transmission of an all 1s signal to the line interface. XLAIS = 1
after a reset allowing immediate generation of alarm signal as long as a clock
source is present. The default value is XLAIS = 1.
The LOOPA bit is used in conjunction with LOOPB to select the channel loopback
modes. See Table 10, Loopback Control, from page 44 repeated below for refer-
ence.
2
LOOPB
3
LOOPA
4—7
—
Reserved.
Write to 0.
Operation
Symbol
—
FLLOOP
2
RLOOP
3
DLLOOP
LOOPA
0
0
1
1
LOOPB
0
1
0
1
Normal
1
Full Local Loopback
Remote Loopback
Digital Local Loopback