Data Sheet
June 2003
TTSV02622 STS-24 Backplane Transceiver
Architecture
(continued)
The alignment FIFO allows the transfer of all data to the system clock. The FIFO sync block allows the system to
be configured to allow the frame alignment of multiple slightly varying data streams (see the FIFO Sync Subblock
STS-12
STREAM A
STS-12
STREAM B
FIFO
SYNC
Figure 6. Interconnect of Streams for FIFO Alignment
The pointer mover (see the Pointer Mover Subblock (Backplane to Line) section on page 28) is responsible for
mapping incoming frames to line frames. The pointer mover is a pseudo SONET implementation which is
streamlined wherever possible to minimize gate count and complexity. As a result, it is only capable of correcting
single bit, nonrepeating pointer errors. This pointer mover (i.e., interpreter, elastic store, and generator) will be
capable of handling intra STS-12 concatenation as well as inter STS-12 concatenation as long as the STS-12
streams are frame aligned.
Powerdown Mode
Powerdown mode should be entered when the corresponding channel is disabled. Channels can be independently
enabled or disabled under software control.
Note:
The EXT PROT SW FUNC is low for STS-12 mode.
When a channel is disabled, the disabled channel of the clock and data recovery module is powered down, as well
as the LVDS buffers and TTL buffers for that channel. When all channels are powered down, PLL in the CDR mod-
ule is also powered down.
In addition, a pin has been added to enable the LVDS pins during boundary scan. This pin should be pulled high on
the board for functional operation.
Agere Systems Inc.
19
AGERE [ AGERE SYSTEMS ]
