ST70235A

ST70235A ASCOTTM DMT TRANSCEIVER PRELIMINARY DATA s DMT MODEM FOR CPE ADSL, COMPATIBLE WITH THE FOLLOWING STANDARDS: - ANSI T1.413 ISSUE 2 - ITU-T G.992.1 (G.DMT) - ITU-T G.992.2 (G.LITE) 1 & 2) OR BITSTREAM INTERFACE s SUPPORTS EITHER ATM (UTOPIA LEVEL s 16 BIT MULTIPLEXED MICROPROCESSOR INTERFACE (LITTLE AND BIG ENDIAN COMPATIBILITY) s ANALOG FRONT END MANAGEMENT s DUAL LATENCY INTERLEAVED PATHS: FAST AND s ATM’S PHY LAYER: CELL PROCESSING (CELL DELINEATION, CELL INSERTION, HEC) s ADSL’S OVERHEAD MANAGEMENT s REED SOLOMON ENCODE/DECODE s TRELLIS ENCODE/DECODE (VITERBI) s DMT MAPPING / DEMAPPING OVER 256 CARRIERS GENERAL DESCRIPTION The ST70235A is the DMT modem and ATM framer of the STMicroelectronics ASCOT™ chipset. When coupled with ST70134 analog front-end and an external controller running dedicated firmware, the product fulfills ANSI T1.413 "Issue 2" DMT ADSL specification. The chip supports UTOPIA level 1 and UTOPIA level 2 interface. The ST70235A can be split up into two different sections. The physical one performs the DMT modulation, demodulation, Reed-Solomon encoding, bit interleaving and 4D trellis coding. The ATM section embodies framing functions for the generic and ATM Transmission Convergence (TC) layers. The generic TC consists of data scrambling and Reed Solomon error corrections, with and without interleaving. The ST70235A is controlled and programmed by an external controller (ADSL Transceiver Controller, ATC) that sets the programmable coefficien...