APPLICATIONS
„ Voice over IP/DSL — Integrated Access Devices (IAD),
Smart Residential Gateways (SRG), Home Gateway/
Router
„ Cable Telephony — NIU, Set-Top Box, Home Side
Box, Cable Modem, Cable PC
„ Fiber — Fiber in the Loop (FITL), Fiber to the
Home (FTTH)
„ Wireless Local Loop, Intelligent PBX
„ DLC-MUX
„ CO

FEATURES
„ High performance digital signal processor provides
programmable control of all major line card functions
— A-law/µ-law and linear codec/filter
– Transmit and receive gain
– Two-wire AC impedance
– Transhybrid balance
– Equalization
— DC loop feeding
– Smooth or abrupt polarity reversal
— Loop supervision
– Off-hook debounce circuit
– Ground-key and ring-trip filters
— Internal ringing generation and integrated ring-trip
detection
— Adaptive hybrid balance
— Line and circuit testing
– Meets GR-909 and GR-844 test requirements
— Tone generation (DTMF, FSK, random noise, and
arbitrary tone)
— Metering generation at 12 kHz and 16 kHz
– Envelope shaping and level control
— Modem Tone Detection
„ Selectable PCM/MPI or GCI digital interfaces
— Supports most available master clock frequencies from
512 kHz to 8.192 MHz
„ General purpose I/O pins
„ +3.3 V DC operation
„ Exceeds LSSGR and ITU requirements
„ Supports external ringing with on-chip ring-trip circuit
— Automatic or manual ring-trip modes
„ Supports CallerNumber Identification (CID) tone
generation

DESCRIPTION
The Le79228 Quad Intelligent Subscriber Line Audioprocessing Circuit (ISLAC™) device, in combination with a
VE790 series ISLIC™ device, implements a four-channel
universal telephone line interface. This enables the design of a
single, low cost, high performance, fully software
programmable line interface for multiple country applications.
All AC, DC, and signaling parameters are fully programmable
via microprocessor or GCI interfaces. Additionally, the
Le79228 Quad ISLAC device has integrated self-test and linetest capabilities to resolve faults to the line or line circuit. The
integrated test capability is crucial for remote applications
where dedicated test hardware is not cost effective.