2.0 Functional Description
CX28331/CX28332/CX28333
2.2 Transmitter
Single/Dual/Triple E3/DS3/STS-1 Line Interface Unit
2.2.4 Alarm Indication Signal (AIS) Generator
When TAIS is asserted, an AIS replaces the transmit data at TPOS and TNEG.
The E3 type of AIS signal (all 1s) is supported. In three-level signal form, this is a
continuously alternating positive and negative pulse stream, as if the transmit data
were a continuous string of logical 1s. Figure 2-7 illustrates the AIS signal.
The TAIS pin has the same data latency as the TX data pins and can be used to
replace single symbols within a data stream. When the encoder is disabled
(ENDECDIS = 1), the TAIS mode maintains the proper phase, based upon the
polarity of the last 1 received.
The AIS signal follows the same path as the TX data during remote or local
loopback.
Figure 2-7. AIS Signal
POSITIVE
PULSE
NEGATIVE
PULSE
TLINEP
(output voltage)
TLINEN
(output voltage)
8333_009
2.2.5 Transmit Monitor Block (CX2833i-3x Only)
The transmit monitor inputs (TMONP and TMONM) are designed to monitor the
line driver outputs (TLINEP and TLINEM/N) for pulses and to assert a Loss Of
Signal (TLOS) indicator when no output pulse has been detected for 32 TCLK
periods. After TLOS is asserted, it will not deassert until a pulse is again
detected. The transmit monitor is an independent function in which TMONP and
TMONM must be externally connected to TLINEP and TLINEM/N, respectively.
A special pin (TMONTST) is available for testing board-level functionality
downstream from the TLOS outputs. When TMONST is high it will assert all
TLOS channel outputs. TLOS outputs are active high when the monitor inputs do
not detect a signal.
2-8
Conexant
100985A
CONEXANT [ CONEXANT SYSTEMS, INC ]
