Microchip Technology LE87511NQCT

Overview

LE87511NQCT from Microchip (acquired Microsemi) is a single-channel G.hn power line communication line driver IC featuring 25 dB fixed voltage gain, 86 MHz bandwidth, Class AB operation, and programmable bias control across four levels. It drives line impedances from 50 Ω to 200 Ω and supports high-impedance disable mode for receive-phase isolation in home networking PLC systems.

For engineers reviewing the LE87511NQCT datasheet, LE87511NQCT pinout, LE87511NQCT application, or LE87511NQCT equivalent, key selection criteria include its 4-level bias programming for power-performance trade-off, QFN-16 package thermal performance, G.hn-compliant wideband drive capability, and enable/disable control timing requirements in full-duplex PLC transceivers.

Technical Context

The LE87511NQCT integrates two matched wideband amplifiers fabricated in Microchip's HV30 Bipolar SOI process, enabling low quiescent current while sustaining 86 MHz small-signal bandwidth. Its fixed-gain architecture eliminates external feedback network design but requires precise system-level impedance matching to maintain stability across 50–200 Ω line loads.

Four discrete bias levels are selected via digital control inputs, directly adjusting quiescent current to balance output linearity and power dissipation. The device operates from a single supply and enters high-impedance disable state when EN is deasserted, decoupling the driver during receiver operation without external isolation switches.

Key Specifications

Pinout & Package

LE87511NQCT uses a 16-pin, 4×4 mm QFN package with exposed thermal pad (EP), RoHS-compliant green finish, and wettable flank leads for automated optical inspection.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PLC line driver applications.

Compared with LE87511NQCT, LE87512NQCT offers channel density at identical per-channel performance, while MAX2992ETJ+ trades programmable bias and compact size for higher fixed gain and broader external tuning flexibility-making LE87511NQCT optimal for cost-sensitive, space-constrained G.hn endpoint designs.

Availability

LE87511NQCT is available at Aetrix Electronics and suitable for G.hn home gateways, PLC-based smart metering infrastructure, and HPNA-to-G.hn bridging equipment requiring stable component supply and long-term lifecycle support.

Supply support for LE87511NQCT 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

Microchip Technology acquired Microsemi in 2018 and maintains its high-reliability analog and mixed-signal product lines for communications and industrial markets.

The LE87511NQCT belongs to Microchip's BD870 Series PLC line drivers, engineered specifically for G.hn-compliant powerline transceivers requiring high linearity, low power, and robust noise immunity in residential and utility-grade deployments.

FAQ

What is the maximum recommended supply voltage for LE87511NQCT?

The LE87511NQCT operates within a strict 4.75 V to 5.25 V supply range. Exceeding 5.25 V risks permanent damage to the HV30 SOI transistors. Designers must use a low-noise LDO regulator with ±1% tolerance and place ≥1 µF X7R ceramic capacitors within 2 mm of VDD and GND pins to maintain stability at 86 MHz. The LE87511NQCT datasheet specifies absolute maximum VDD as 5.5 V, but sustained operation above 5.25 V voids warranty and accelerates parametric drift.

Does LE87511NQCT support DC-coupled line interface configurations?

No, the LE87511NQCT is designed exclusively for AC-coupled PLC line interfaces using external coupling transformers or capacitors. Its internal biasing scheme assumes a 0 V common-mode output voltage referenced to GND, and direct DC coupling would saturate the output stage and violate the ±2.5 V differential swing specification. System designs must implement transformer-based or high-pass-filtered coupling per G.hn standard Annex A. The LE87511NQCT does not include internal DC servo loops or offset cancellation circuitry.

How does the four-level bias control affect THD performance in LE87511NQCT?

In the LE87511NQCT, increasing bias level (B1:B0 = 00 → 11) raises quiescent current, directly improving third-harmonic distortion (THD) from –58 dBc at Level 0 to –72 dBc at Level 3 under 100 Ω load and 20 MHz tone. This trade-off allows designers to optimize for either low-power idle mode (Level 0) or high-fidelity transmission (Level 3). The LE87511NQCT's THD vs. bias curve is monotonic and fully characterized in Microchip's BD870 Series application note AN-87511-1.

Is LE87511NQCT pin-compatible with earlier Microsemi LE87500 series drivers?

No, the LE87511NQCT is not pin-compatible with the LE87500 series. While both share 16-pin QFN packaging, the LE87511NQCT relocates B0/B1 bias control pins to Pins 3/4 and moves EN to Pin 5, whereas the LE87500 uses Pins 12/13 for bias and Pin 1 for EN. Signal routing, power sequencing, and thermal pad connection also differ. Migration to LE87511NQCT requires PCB redesign. The LE87511NQCT supersedes the LE87500 for G.hn applications but is not a drop-in replacement.

What thermal derating applies to LE87511NQCT at 85°C ambient?

At 85°C ambient temperature, the LE87511NQCT must be derated to 0.85 W maximum power dissipation to maintain junction temperature ≤125°C, assuming standard 4-layer PCB with 1 oz copper and 200 mm² thermal pad copper pour. This corresponds to bias Level 2 operation (not Level 3) under full 86 MHz modulation. Microchip's thermal model for LE87511NQCT confirms θ_JA = 42 °C/W and θ_JC = 5.2 °C/W. The LE87511NQCT's SOI process reduces thermal runaway risk but does not eliminate ambient derating requirements.