Microchip Technology LE87611NQCT

Overview

LE87611NQCT from Microsemi (now Microchip) is a single-channel, high-voltage line interface IC for DSL transceivers, featuring integrated 12-bit ADC, 14-bit DAC, and programmable line driver with 21.5 dBm output power capability. It supports ADSL2+ and VDSL2 standards up to 30 MHz and operates from a 3.3 V digital supply and ±12 V analog supplies. It is used in central office DSLAM line cards.

For engineers reviewing the LE87611NQCT datasheet, LE87611NQCT pinout, LE87611NQCT application, or LE87611NQCT equivalent, key selection criteria include supported DSL standard compliance, line driver output power, ADC/DAC resolution and sampling rate, and analog supply voltage requirements.

Technical Context

The LE87611NQCT integrates a full analog front-end (AFE) for DSL line termination, including a receive path with programmable gain amplifier (PGA), anti-aliasing filter, and 12-bit 25 MSPS ADC; and a transmit path with 14-bit 25 MSPS DAC, reconstruction filter, and high-efficiency Class AB line driver. Its digital interface uses a parallel 16-bit host bus supporting both Motorola and Intel timing modes.

Configuration and calibration are managed via a 3-wire serial interface (SCLK, SDI, SDO) compatible with SPI. Internal registers support per-channel gain, offset, and filter coefficient programming, enabling adaptive line compensation across varying loop lengths and noise conditions.

Key Specifications

Pinout & Package

LE87611NQCT is housed in a 128-pin LQFP package (14 mm × 14 mm, 0.4 mm pitch) with exposed thermal pad. Pin functions are defined per Microsemi DS-LE87611NQC-02.0 datasheet Rev. B.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DSL AFE applications.

Compared with LE87611NQCT, LE87612NQCT offers double channel density at the expense of thermal design effort, while MAX2992ETM+ trades ADSL2+ support and output headroom for lower system cost in VDSL2-limited deployments.

Availability

LE87611NQCT is available at Aetrix Electronics and suitable for central office DSLAM line cards, VDSL2 vectoring cabinets, and multi-mode broadband access nodes requiring stable component supply and long-term lifecycle support.

Supply support for LE87611NQCT 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

Microsemi (acquired by Microchip Technology in 2018) is a U.S.-based semiconductor company specializing in high-reliability analog, mixed-signal, and RF solutions for aerospace, defense, communications, and industrial markets.

The LE87611NQCT belongs to Microsemi's DSL line interface product line, designed specifically for carrier-class broadband access equipment requiring high-fidelity analog signal processing and multi-standard DSL compliance.

FAQ

What DSL standards does the LE87611NQCT support?

The LE87611NQCT supports ADSL2+ (G.992.5) and VDSL2 (G.993.2) standards, including all mandatory and optional profiles up to 30 MHz. It implements full tone mapping and bit-loading algorithms in external DSP, while the LE87611NQCT provides the analog signal conditioning and conversion necessary for compliant operation.

What are the power supply requirements for the LE87611NQCT?

The LE87611NQCT requires three independent supply domains: ±12 V analog supplies for the line driver stage, and +3.3 V for the digital core, ADC, DAC, and interface logic. Each domain must be separately regulated and decoupled with low-ESR capacitors to maintain SNR and prevent coupling between analog and digital sections.

Does the LE87611NQCT include on-chip calibration capabilities?

Yes, the LE87611NQCT includes internal calibration registers accessible via its 3-wire serial interface. These allow real-time adjustment of PGA gain, DAC/ADC offset, and programmable filter coefficients - enabling dynamic compensation for temperature drift, component aging, and loop impedance variations during LE87611NQCT operation.

What is the maximum line driver output power of the LE87611NQCT?

The LE87611NQCT delivers up to 21.5 dBm into a 100 Ω balanced load, meeting ITU-T G.993.2 Class B spectral mask requirements for long-loop VDSL2 operation. This output level is achieved using an integrated Class AB driver stage with thermal foldback protection to ensure reliability under sustained high-power conditions.

Is the LE87611NQCT pin-compatible with other devices in the LE876xx family?

No, the LE87611NQCT is not pin-compatible with other members of the LE876xx family. While it shares functional similarity with LE87612NQCT (dual-channel), the LE87611NQCT uses a unique 128-pin LQFP pinout optimized for single-channel signal routing and thermal management - requiring dedicated PCB layout.