ds2156gn Maxim Integrated Products, Inc., ds2156gn Datasheet - Page 111

• Manufacturer Part Number: ds2156gn
• Description: Ds2156, Ds2156l, Ds2156ln T1/e1/j1 Single-chip Transceiver Tdm/utopia Ii Interface
• Manufacturer: Maxim Integrated Products, Inc.

DS2156
18.
ELASTIC STORES OPERATION
The elastic store function is unavailable when UTOPIA backplane is enabled.
The DS2156 contains dual two-frame elastic stores, one for the receive direction and one for the transmit
direction. Both elastic stores are fully independent. The transmit and receive-side elastic stores can be
enabled/disabled independently of each other. Also, each elastic store can interface to either a 1.544MHz
or 2.048MHz/4.096MHz/8.192MHz/16.384MHz backplane without regard to the backplane rate the other
elastic store is interfacing to.
The elastic stores have two main purposes. Firstly, they can be used for rate conversion. When the
DS2156 is in the T1 mode, the elastic stores can rate-convert the T1 data stream to a 2.048MHz
backplane. In E1 mode, the elastic store can rate-convert the E1 data stream to a 1.544MHz backplane.
Secondly, they can be used to absorb the differences in frequency and phase between the T1 or E1 data
stream and an asynchronous (i.e., not locked) backplane clock, which can be 1.544MHz or 2.048MHz. In
this mode, the elastic stores manage the rate difference and perform controlled slips, deleting or repeating
frames of data in order to manage the difference between the network and the backplane.
The elastic stores can also be used to multiplex T1 or E1 data streams into higher backplane rates, which
is the IBO discussed in Section 28.
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