STMicroelectronics L6711

Overview

L6711 from STMicroelectronics is a 3-phase synchronous buck controller with integrated 2A gate drivers, designed for high-current CPU voltage regulation in desktop/server/workstation VRM/VRD systems. It delivers 0.5% output voltage accuracy, supports dynamic VID programming (6-bit/5-bit DAC), and features fully differential current sensing across either low-side MOSFETs or inductors, with 150kHz per-phase switching (450kHz ripple) and integrated thermal sensing.

For engineers reviewing the L6711 datasheet, L6711 pinout, L6711 application, or L6711 equivalent, this controller enables precise multi-phase DC/DC conversion with selectable current-sense topology, programmable OVP/UVP, digital soft-start, remote voltage sense, and phase-shifted 120° operation - critical for high-density, thermally constrained CPU power delivery designs.

Technical Context

The L6711 implements a three-phase, 120° phase-shifted PWM control architecture with adaptive anti-cross-conduction logic per channel and independent high- and low-side driver sections (VCCDRx supplies). Its current-sharing loop maintains ≤3% active current imbalance across phases using averaged current feedback and correction.

Dynamic VID management is implemented via dual DAC tables selected by VID_SEL: VRD10.x-compliant (0.8185–1.5810V, 12.5mV steps) or VRM-Hammer-compliant (0.800–1.550V, 25mV steps), both with ±0.5% accuracy over line and temperature. The oscillator supports fixed 150kHz/channel or external frequency adjustment via OSC/FAULT pin current sinking (6kHz/µA gain).

Key Specifications

Pinout & Package

TQFP48 (7×7 mm, exposed thermal pad), RoHS-compliant package optimized for high-power density and thermal dissipation in multi-phase VRMs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-phase CPU voltage controller applications.

Compared with ISL6322 and RT8803, the L6711 uniquely combines dual-standard VID DACs, fully differential selectable current sensing, integrated thermal compensation, and remote sense buffering - making it the only option among the three that supports both VRD10.x and VRM-Hammer compliance while maintaining <3% current sharing accuracy across temperature.

Availability

L6711 is available at Aetrix Electronics and suitable for high-current VRM/VRD for desktop/server/workstation CPUs, high-density DC/DC converters, and embedded processor power delivery systems requiring stable component supply and long-term industrial availability.

Supply support for L6711 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and computing markets.

The L6711 belongs to ST's VRM/VRD controller product line, engineered specifically for high-efficiency, multi-phase CPU core voltage regulation with dynamic VID compliance and robust protection in thermally demanding environments.

FAQ

What is the function of the CS_SEL pin on the L6711?

The CS_SEL pin selects the current sensing method: when left floating, it enables low-side MOSFET current sensing with duty-cycle limiting and Track&Hold for accurate sampling; when shorted to SGND, it enables inductor DCR sensing without duty-cycle restriction. This choice directly impacts layout complexity, efficiency trade-offs, and transient response fidelity.

How does the VID_SEL pin affect output voltage programming?

VID_SEL determines which DAC table governs the output voltage: floating selects the VRD10.x-compliant 6-bit table (0.8185–1.5810V, 12.5mV steps); grounded selects the VRM-Hammer-compliant 5-bit table (0.800–1.550V, 25mV steps). Both tables define corresponding OVP/UVP thresholds, ensuring full standard compliance without external logic.

Can the L6711 operate without remote sensing?

Yes - if remote sensing is not used, connect VSEN directly to the regulated output node, and leave FBR and FBG unconnected or tied to VSEN. The internal remote sense buffer remains functional but operates as a unity-gain local sense amplifier, preserving OVP/UVP protection integrity without requiring Kelvin traces.

What happens during an overvoltage fault on the L6711?

Upon OVP detection, the OSC/FAULT pin is pulled high (≈5V), all PWM outputs halt, and an internal crowbar activates by turning on the low-side MOSFETs to clamp output voltage. Recovery requires cycling either the OUTEN pin (low-to-high) or VCC supply - no external latch-reset circuitry is needed.