PM8621 datasheet(142/184 Pages) PMC

142 / 184 page

NSE-8G™ Standard Product Data Sheet

Preliminary

Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use

141

Document ID: PMC-2010850, Issue 1

Figure 23 Switch Timing - DSOs without CAS

0us

250us

500us

C1FP

All CMPs

SBI Frame Time

Internal Sigs

SBS IC1FP.INT

NSE RC1FP.INT

SBS RC1FP.INT

SBS OC1FP.INT

SBS TCMP.INT

NSE CMP.INT

SBS OCMP.INT

12.3.3 SBS/NSE-8G non-DS0 Level Switching with SBI336 Devices

The SBS and NSE-8G supports another mode of operation that has lower latency and lower

power when not switching at the DS0 level. In this mode both of these devices become a column

switch rather than a DS0 switch. This also saves SW configuration since only one row of the

switch configuration rams has to be configured rather than all nine rows.

When switching DS0 through the system the SBS must store an entire frame of DS0s before

routing them to the destination to allow for the last DS0 of a frame to be switched to the first DS0

of the output. When doing column switching only one row of the SBI structure needs to be stored

before switching can take place.

Figure 22 from the previous section can be used here. The following timing diagram shows the

system timing for this mode of operation.

PM8621 Datasheet(PDF) 142 Page - PMC-Sierra, Inc