DS3181 Maxim Integrated Products, DS3181 Datasheet - Page 143

• Manufacturer Part Number: DS3181
• Description: Network Controller & Processor ICs DS3-E3 ATM-Packet PH Y with Built-in Line
• Manufacturer: Maxim Integrated Products

Specifications of DS3181

• Product: Framer
• Number Of Transceivers: 1
• Data Rate: 44.736 Mbps
• Supply Voltage (max): 3.465 V
• Supply Voltage (min): 3.135 V
• Supply Current (max): 280 mA
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C
• Mounting Style: SMD/SMT
• Package / Case: TEBGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

DS3181/DS3182/DS3183/DS3184
Figure 10-26. Receive DSS Scrambler Synchronization State Diagram
Steady
State
8 Cells Fail Verification
Verification
Acquisition
32 Samples Loaded
If cell processing is disabled, a cell boundary is arbitrarily chosen, and the data is divided into "cells" whose size is
programmable. If HEC transfer is enabled in the receive system interface, the incoming data stream will be divided
into 53-byte "cells". If HEC transfer is disabled in the receive system interface, the data is divided into 52-byte
"cells". These cells are then passed on to bit reordering bypassing cell delineation, OCD detection, cell filtering,
header pattern comparison, HEC error monitoring, and HEC byte filtering.
Cell delineation determines the cell boundary by identifying the header bytes and the HEC byte of a cell, and
detects an out of cell delineation (OCD) condition or a change of cell delineation (COCD). Cell delineation is
performed off-line, and the data path cell boundary is only updated by cell delineation if an OCD condition is
present. Performing cell delineation off-line results in fewer cells being discarded when the cell boundary changes.
If DSS scrambling is enabled (bit synchronous mode only), only the six least significant bits (LSBs) of the HEC
(HEC[3:8]) are used for cell delineation, as the two most significant bits (MSBs) are scrambled. An OCD condition
is declared if seven consecutive cells are received with incorrect HEC bytes. An OCD condition is terminated if
“Delta” consecutive cells are received with correct HEC bytes, if cell delineation updates the data path cell
boundary, or if the PLCP framer updates the data path cell boundary (PLCP modes only). All ATM cells are
discarded during an OCD condition. A COCD is declared when Cell Delineation or the PLCP framer updates the
data path cell boundary with a cell boundary that is different from the current data path cell boundary .
Cell delineation has three states: "Hunt", "Presync", and "Sync". The "Hunt" state searches for the cell boundary.
Each time slot is checked for an HEC byte (six LSBs of the HEC byte if DSS is enabled). The cell boundary is set
once the header and HEC bytes are identified, and cell delineation transitions to the “Presync” state. The "Presync"
state verifies the cell boundary identified in the “Hunt” state. The HEC is checked in each incoming cell. If “Delta”
cells (including the "Hunt" to "Presync" transition cell) with a correct HEC are received, cell delineation transitions
to the “Sync” state. If a cell with an incorrect HEC is received, cell delineation transitions to the “Hunt” state. The
"Sync" state checks the HEC in each cell. If a cell with a correct HEC is received, cell delineation updates the data
path cell boundary if an OCD condition is present. If a cell with an incorrect HEC is received, cell delineation
transitions to the “Hunt” state. The cell delineation state diagram is shown in
Figure
10-27. The cell delineation
process starts in the "Hunt" state. In octet-aligned mode, the HEC check is performed one byte at a time, so up to
53 checks may be needed to find the cell boundary. In bit synchronous mode, the HEC check is performed one bit
at a time, so up to 424 checks may be needed to find the cell boundary. HEC calculation coset polynomial addition
can be disabled. The cell delineation process can be programmed to ignore the first header byte (for DQDB
applications) when calculating the HEC. If cell processing is disabled, cell delineation will not be performed. A
“Delta” of eight is used during the DS3 clear-channel, STS-1 clear-channel, and E3 clear-channel modes. A “Delta”
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