CX28331 datasheet(40/68 Pages) CONEXANT

40 / 68 page

2.0 Functional Description

CX28331/CX28332/CX28333

2.2 Transmitter

Single/Dual/Triple E3/DS3/STS-1 Line Interface Unit

2-8

Conexant

100985A

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.

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.

Figure 2-7. AIS Signal

POSITIVE

PULSE

NEGATIVE

PULSE

TLINEP

(output voltage)

TLINEN

(output voltage)

8333_009

CX28331 Datasheet(PDF) 40 Page - Synaptics Incorporated.