PM4354-PI datasheet(73/463 Pages) PMC

73 / 463 page

RELEASED

PM4354 COMET-QUAD

DATASHEET

PMC-1990315

ISSUE 6

FOUR CHANNEL COMBINED E1/T1/J1

TRANSCEIVER / FRAMER

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC. AND FOR ITS CUSTOMERS’ INTERNAL USE

9.21 Transmit Elastic Store (TX-ELST)

The Transmit Elastic Store (TX-ELST) provides the ability to decouple the line timing from the

backplane timing. The TX-ELST is required whenever the backplane and lineside clocks are not

traceable to a common source.

When the elastic store is being used, if the average frequency of the backplane data is greater

than the average frequency of the line clock, the buffer will fill. Under this condition a controlled

slip will occur upon the next frame boundary. The following frame of PCM data will be deleted.

If the average frequency of the backplane data is less than the average frequency of the line

clock, the buffer will empty. Under this condition a controlled slip will occur upon the next frame

boundary. The last frame will be repeated.

A slip operation is always performed on a frame boundary. The TX-ELST is upstream of the

frame overhead insertion; therefore, frame slips do not corrupt the frame alignment signal.

When the line timing is derived from CTCLK or BTCLK is an output, the elastic store is bypassed

to eliminate the one frame delay.

9.22 T1 Basic Transmitter (T1-XBAS)

The T1 Basic Transmitter (T1-XBAS) block generates the 1.544 Mbit/s T1 data stream according

to SF or ESF frame formats.

In concert with the Transmit Per-Channel Serial Controller (TPSC), the T1-XBAS block, provides

per-channel control of idle code substitution, data inversion (either all 8 bits, sign bit magnitude or

magnitude only), and zero code suppression. Three types of zero code suppression (GTE, Bell

and "jammed bit 8") are supported and selected on a per-channel basis to provide minimum ones

density control. An internal signaling control stream provides per-channel control of robbed bit

signaling and selection of the signaling source. All channels can be forced into a trunk

conditioning state (idle code substitution and signaling conditioning) by use of the Master Trunk

Conditioning bit in the Configuration Register.

A data link is provided for ESF mode. The data link sources include bit oriented codes and HDLC

messages. Support is provided for the transmission of framed or unframed Inband Code

sequences and transmission of AIS or Yellow alarm signals for all formats.

The transmitter can be disabled for framing via the disable bit in the Transmit Functions Enable

the backplane transmit stream can be by-passed to the output PCM stream. Finally, the

transmitter can be by-passed completely to provide an unframed operating mode.

PM4354-PI Datasheet(PDF) 73 Page - PMC-Sierra, Inc