Overview
The Interworking Element for 8 E1/T1 Lines PXB4219 / PXB4220 / PXB4221 (IWE8) is a member of Infineon’s ATM chip set. Together with framing and line interface components (e.g. Infineon’s QuadFALC PEB 22554) the IWE8 serves as gateway between Asynchronous Transfer Mode (ATM) networks and timeslot based PDH networks.

Features
• Full duplex ATM Packetizer/Depacketizer for 8 E1/T1 highways
• Configurable to T1 or E1 mode via external pin
• 8 T1/E1 ports configurable independently to ATM or AAL Mode
• ATM Mode (PXB 4219/4220/4221):
   – ATM cell mapping into PDH according to ITUT G.804 [26]
   – B-ISDN User-Network interface - Physical Layer according to ITU-T I.432 [32]
   – B-ISDN User-Network interface - Physical Layer oparation at 1544 KBit/s and 2048 KBit/s according to ITU-T I.432.3 [34]
• AAL Mode (PXB 4220/4221):
   – AAL1 according to ITU-T I.363.1 [31] or transparent without any adaptation layer overhead (AAL0)
   – T1/E1 unstructured service according to ATM Forum af-vtoa-0078.000 [10] section 3
   – Structured T1/E1 N x 64 Kbit/s service according to [10] section 2 with M channels of N x 64 Kbit/s (M,N = 1to 24 for T1) (M,N = 1to 32 for E1)
   – Channel Associated Signalling (CAS) support according to [10]
   – Echo Canceller Mode
   – Partially filled cells with programmable filling thresholds
   – Selectable Sequence Count Algorithm:
   – Robust/Fast according to ITU-T I.363.1 [30]
   – According to ETSI (prl-ETS 300353 annex D) [17]
   – Fast: Saves 6 ms during reassembly for 1 x 64 Kbit/s connection
   – AAL0 option: 48 Bytes user payload per ATM Cell, without AAL overhead
   – Reassembly buffer can compensate up to +/- 4 ms Cell Delay Variation (CDV)
   – Statistics counters per channel for lost/misinserted/errored cells etc.
   – Internal clock recovery circuit using Synchronous Residual Time Stamp (SRTS) or Adaptive Clock Method (ACM) for unstructured CES ports. For SRTS a patent fee needs to be paid. Optionally, it’s possible to order the PXB 4221 device, which comes without SRTS clock recovery.
   – Trunk freezing and conditioning according to Bellcore TR-NWT-000170 [14]
• IMA interface:
   – Programmable threshold between read and write pointer of Mapping Buffer
   – Output Signal for buffer threshold crossing
   – Output Signal for discarded cell
   – Output pins for port number indication
• 8 generic framer interfaces with integrated transmit clock selector supporting
   – Synchronous Mode (SYM)
   – Generic Interface Mode (GIM)
   – FALC Mode (FAM): Glue-less interface for Infineon’s Framer and Line Interface Components (FALC)
   – Echo Canceller Mode (EC): ATM cells are duplicated internally and transmitted via two framer ports
• UTOPIA industry standard interface:
   – Level 2 in slave mode; 8 data, 5 address lines
   – Level 1 in master/slave mode
– UTOPIA clock up to 38.88 MHz
• 16-bit generic microprocessor interface for control and configuration of the chip runs either in Intel 386EX or Motorola compatible mode
• External synchronous Flow-Through SSRAM 1 x 64K x 33 bit or 1 x 64K x 32 bit required
• Build-in data path loops for test
• Cell insertion/extraxtion via microprocessor interface
• 3.3 Volt power supply with 5 Volt tolerant inputs
• Typical power dissipation 1 Watt
• P-BGA 256 package
• Temperature range from -40° to +85°C