CN8380 Datasheet, PDF (34/91 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
In Hardware Mode, AIS can be controlled only manually by pulling the
TAIS[n] hardware pin low. If TCLK[n] is present, then it is used to transmit AIS.
If TCLK[n] is not present (for two clock periods), the alternate AIS clock on
either TACKI (T1 Mode) or EACKI (E1 Mode) is used. The AIS transmit clock
switches back to TCLK[n] when the TCLK[n] signal returns.
In Host Mode, AIS can be transmitted using the TAIS[n] hardware pins or the
TAIS register bit, or automatically by enabling the AUTO_AIS register bit. AIS
clock switching can be enabled by using the AISCLK register bit. Setting
AISCLK to 1 forces the use of the alternate AIS clock on either TACKI (T1
Mode) or EACKI (E1 Mode) pins when transmitting AIS. If AUTO_AIS is set
to 1, AIS is automatically transmitted when the clock monitor detects loss of
clock on TCLK[n]. When using automatic AIS transmission, the user should also
enable the AISCLK bit and provide an alternate clock source to insure that AIS
will be transmitted. CLAD output clocks CLK2048 and CLK1544 can be
connected externally to EACKI and TACKI alternate AIS clock inputs for this
purpose. Setting register bit TAIS_PE to 1 disables the TAIS register bit and
allows manual transmission of AIS using the TAIS[n] hardware pins. Refer to
LIU_CTL [addr n3] in Chapter 3.0, Registers, and to Table 1-1, Hardware Signal
Definitions.
If TAIS is activated when Remote Line Loopback is active, AIS is transmitted
using the received clock (or JCLK if the JAT is enabled in the receive direction).
Table 2-2 lists transmitter operating modes resulting from various configuration
settings and input conditions.
Table 2-2. Transmitter Operating Modes
Configuration and Input Status
RLOOP
(W/LLOOP=0)
TLOC
TAIS
AUTO_AIS
0
X
0
0
0
X
1
X
0
X
1
X
AISCLK
X
0
1
Transmitter Mode
Transmit
Data
Transmit
Clock
Tx Data
AIS
AIS
TCLK
TCLK
TACKI/EACKI
0
0
0
0
1
0
0
1
0
1
X
Tx Data
TCLK
1
0
AIS
TCLK
1
1
AIS
TACKI/EACKI
1
X
0
1
X
1
NOTE(S): X is don’t-care.
X
X
Rx Data
RCLK
X
X
AIS
RCLK
2-12
Conexant
N8380DSA
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