Microchip Technology LE79Q2284MVCT

Overview

LE79Q2284MVCT from Zarlink Semiconductor (acquired by Microsemi, now part of Microchip) is a quad-channel intelligent subscriber line audio-processing circuit (ISLAC™) designed to interface with VE790-series ISLIC™ devices for full BORSCHT functionality across four telephone lines. It delivers programmable A-law/µ-law/linear codec filtering, transhybrid balance, DC loop feeding, ring-trip detection, and integrated tone generation (DTMF, FSK, metering at 12/16 kHz), targeting VoIP/DSL IADs and fiber-to-the-home gateways.

For engineers reviewing the LE79Q2284MVCT datasheet, LE79Q2284MVCT pinout, LE79Q2284MVCT application, or LE79Q2284MVCT equivalent, this device requires attention to its 80-pin LQFP package, GCI/PCM dual-interface support, 3.3 V operation, channel-specific analog sensing inputs (VILG/VIMT), and software-configurable supervision thresholds - all critical for carrier-grade line card design and GR-909/GR-844 compliance validation.

Technical Context

The LE79Q2284MVCT implements a four-channel digital signal processor core that manages voice conversion, signaling, DC-feed control, and diagnostics for subscriber lines via tightly coupled interaction with external VE790-series bipolar ISLIC devices. It supports selectable PCM/MPI or GCI digital interfaces with master clock flexibility (512 kHz–8.192 MHz) and provides tri-level LD1–LD4 outputs plus P1–P3 mode control signals to configure ISLIC operating modes including feed resistance, current limit, and ringing waveform.

Its analog front-end includes four independent A/D and D/A converters per channel, programmable digital filters for transmit/receive gain, equalization, and transhybrid balance, and dedicated inputs for longitudinal/metallic current (VILG/VIMT) and battery voltage sensing (SHB/SLB/SPB). All supervision functions - off-hook debounce, ground-key detection, ring-trip filtering - are digitally configurable with threshold and timing parameters stored in internal registers.

Key Specifications

Pinout & Package

LE79Q2284MVCT is housed in an 80-pin Low-Profile Quad Flat Pack (LQFP), RoHS-compliant green package, with exposed thermal pad (not electrically connected). Pin functions include dual-mode digital interfaces (DIN/S1, DOUT, DXA/DU, DXB, DRA/DD, DRB), channel-specific analog sensing inputs (VILG1–VILG4, VIMT1–VIMT4), tri-level ISLIC control outputs (LD1–LD4, P1–P3), and battery voltage sense inputs (SHB, SLB, SPB).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad-channel subscriber line interface applications.

Compared with LE79Q2281DVC, LE79Q2284MVCT offers expanded I/O, GCI dual-addressing, and diagnostic capabilities essential for carrier-grade FTTH and IAD platforms; versus ZL38004, it delivers hardware-accelerated BORSCHT with deterministic real-time performance but requires external ISLIC and host processor coordination.

Availability

LE79Q2284MVCT is available at Aetrix Electronics and suitable for Voice over IP gateways, fiber-to-the-home terminals, and cable telephony nodes requiring stable component supply, long-lifecycle support, and GR-909-compliant line interface functionality.

Supply support for LE79Q2284MVCT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Zarlink Semiconductor, acquired by Microsemi in 2011 and later integrated into Microchip Technology, specialized in high-reliability communications ICs for carrier infrastructure and broadband access equipment.

The LE79Q2284MVCT belongs to the VE790-series intelligent line interface chipset, engineered specifically for software-defined, multi-country telephone line cards in carrier-class IADs, NIUs, and optical network terminals.

FAQ

What is the primary function of the LE79Q2284MVCT in a telephone line card?

The LE79Q2284MVCT serves as the quad-channel intelligent subscriber line audio-processing circuit (ISLAC™) that performs all digital signal processing, BORSCHT functions, and ISLIC control for four analog telephone lines. It works exclusively with VE790-series ISLIC devices to implement full line interface functionality - including programmable DC feed, ringing, supervision, hybrid balance, and diagnostics - in carrier-grade VoIP, DSL, and FTTH equipment. Its role is central to achieving software-configurable, globally compliant line cards.

Does the LE79Q2284MVCT support both PCM and GCI digital interfaces?

Yes, the LE79Q2284MVCT supports both PCM/MPI and GCI digital interfaces, selected automatically based on signal presence on FS/DCL and PCLK/FS pins. In PCM mode, it accepts 8/16-bit data at standard rates with frame sync and programmable timeslots; in GCI mode, it operates at 2 MHz data rate with 8 kHz frame sync and supports dual-device addressing via TSCA/G and DIN/S1. This dual-interface capability allows flexible integration into diverse telecom backplane architectures without hardware redesign.

How does the LE79Q2284MVCT handle ring-trip detection?

The LE79Q2284MVCT integrates dedicated ring-trip detection circuitry with programmable thresholds and automatic/manual mode selection. It monitors analog inputs from the VE790 ISLIC (via VILG/VIMT) during ringing to detect current interruption caused by subscriber answering. Detection logic includes configurable debounce timing and can trigger interrupt output (INT) to alert the host processor. The device also supports external ringing generators with synchronized relay control - ensuring precise zero-crossing switching to minimize EMI and meet GR-909 test requirements.

What are the key analog sensing inputs required for LE79Q2284MVCT operation?

The LE79Q2284MVCT requires six critical analog sensing inputs per channel pair: VILG1–VILG4 (longitudinal current), VIMT1–VIMT4 (metallic current), and SHB/SLB/SPB (battery voltage sense nodes). These connect directly to external resistors on the VE790 ISLIC to enable real-time monitoring of loop conditions, off-hook state, ring-trip events, and feed voltage integrity. Accurate biasing of these inputs - typically referenced to on-chip VREF - is essential for meeting GR-844 line test specifications and maintaining longitudinal balance across temperature and voltage variations.

Is WinSLAC™ software required to configure the LE79Q2284MVCT?

WinSLAC™ is not mandatory but strongly recommended for efficient LE79Q2284MVCT configuration. This free PC tool calculates filter coefficients, DC-feed parameters, supervision thresholds, and equalization settings based on system requirements (e.g., country-specific ringing frequency, loop length, impedance). It generates register initialization code and predicts system performance - significantly reducing development time versus manual coefficient derivation. While direct register writes are possible, WinSLAC™ ensures compliance with ITU-T and GR-series standards and validates design margins before hardware prototyping.