STMicroelectronics L6725

Overview

L6725 from STMicroelectronics is a voltage-mode PWM buck controller for low-voltage distributed DC-DC conversion, supporting 1.8V–18V input and 4.5V–18V supply, adjustable output down to 0.6V (±0.8% accuracy over 0°C–125°C), 0%–100% duty cycle, and dual R_DS(on)-based high-side/low-side over-current protection in SO16N package.

For engineers reviewing the L6725 datasheet, L6725 pinout, L6725 application, or L6725 equivalent, this controller delivers predictive anti-cross-conduction control, bootstrap anti-discharging, pre-bias startup, programmable 250 kHz/500 kHz switching, and integrated high-current gate drivers - critical for high-efficiency, high-density synchronous buck designs in graphics cards and server VRMs.

Technical Context

The L6725 implements fixed-frequency voltage-mode control with an internal 10 MHz GBWP error amplifier and 5 V/µs slew rate, enabling fast transient response in low-duty-cycle applications. It supports dual current-sense architecture: peak-current limit via OCH pin (100 µA sink, 100 ns masking) and valley-current limit via OCL pin (100 µA source, 500 ns masking), both using MOSFET R_DS(on) to eliminate external sense resistors.

Its oscillator offers selectable 250 kHz or 500 kHz operation set by EAREF pin voltage (80–95% of VCCDR = 500 kHz, 0–80% = 250 kHz). The bootstrap anti-discharging system maintains gate drive integrity during light-load conditions, while predictive dead-time control dynamically adjusts to phase-node voltage (−350 mV threshold) to minimize cross-conduction without fixed delays.

Key Specifications

Pinout & Package

Package: SO16N (Narrow 16-pin SOIC), 1.27 mm pitch, body size 10.3 × 7.5 mm, thermal resistance R_thJA = 50 °C/W on demo board.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck controller applications.

Compared with ISL6269CRZ-T and TPS54620RGYR, the L6725 provides superior transient response via voltage-mode control with 10 MHz GBWP, unique bootstrap anti-discharge for light-load stability, and independent high-side/low-side current limiting - making it optimal for high-reliability, high-current VRMs where layout control and protection granularity matter.

Availability

L6725 is available at Aetrix Electronics and suitable for graphics card VRMs, server CPU core supplies, and industrial FPGA power systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for L6725 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, Switzerland, designing and manufacturing microcontrollers, power ICs, sensors, and analog devices for automotive, industrial, and consumer markets.

The L6725 belongs to ST's high-performance DC-DC controller product line, engineered specifically for low-voltage, high-current synchronous buck conversion in graphics, computing, and telecom infrastructure - emphasizing precision regulation, thermal resilience, and layout-friendly protection.

FAQ

What is the difference between L6725 and L6725A?

The L6725A adds two functional pins absent in L6725: PGOOD (open-drain output indicating ±10% output voltage tolerance) and SYNCH (master-slave synchronization input). Both share identical control architecture, pinout compatibility, and electrical specs - the A version enables power-good signaling and multi-phase coordination without redesign.

How does the bootstrap anti-discharging system improve light-load efficiency?

The bootstrap anti-discharging system prevents leakage-driven discharge of the BOOT capacitor during low-duty-cycle or discontinuous conduction modes. By maintaining sufficient gate-drive voltage on the high-side MOSFET, it avoids unintended dropout and ensures reliable switching - directly improving regulation stability and reducing output ripple at light loads.

Can L6725 regulate output voltages below 0.6 V?

No - the internal reference is fixed at 0.6 V, and the error amplifier's feedback structure requires V_FB = 0.6 V for regulation. External reference operation supports 0–2.5 V inputs, but the minimum regulated output remains constrained by the 0.6 V reference and FB divider topology; outputs below 0.6 V require external amplification or alternative controller architectures.

What is the purpose of the predictive dead-time control?

Predictive dead-time control monitors the PHASE node voltage during dead time and reduces delay if the low-side body diode conducts (PHASE < −350 mV). This minimizes cross-conduction risk without fixed timing overhead - improving efficiency and thermal performance, especially at high switching frequencies and light loads where traditional fixed dead time causes excessive loss.