STMicroelectronics L6926

Overview

L6926 from STMicroelectronics is a monolithic synchronous step-down DC-DC regulator designed for single-cell Li-Ion battery-powered systems. It operates from 2 V to 5.5 V input, delivers up to 800 mA output current, supports adjustable output down to 0.6 V, achieves up to 95% efficiency, and features 600 kHz fixed-frequency current-mode control with external synchronization capability (500 kHz–1.4 MHz). It is used in portable instruments and handheld terminals requiring low-quiescent-current power conversion.

For engineers reviewing the L6926 datasheet, L6926 pinout, L6926 application, or L6926 equivalent, key selection criteria include its 1 µA shutdown current, ±1% output voltage accuracy, Power Good signal, selectable low-noise/low-consumption modes, and thermal shutdown at 150 °C - all critical for battery life, system reliability, and noise-sensitive embedded designs.

Technical Context

The L6926 implements a slope-compensated current-mode PWM architecture with peak and valley current limiting, enabling stable operation up to 100% duty cycle for ultra-low dropout. Its internal high-side (240–400 mΩ) and low-side (215–400 mΩ) MOSFETs eliminate external Schottky diode requirements.

Two light-load operating modes are controlled via the SYNC pin: low-consumption mode (25–50 µA quiescent current, discontinuous conduction) and low-noise mode (200–300 µA, fixed 600 kHz switching). External synchronization overrides mode selection and enforces low-noise operation while preserving protection functions.

Key Specifications

Pinout & Package

Available in TSSOP8 (3×3×1.0 mm) and VFQFPN8 (3×3×0.9 mm) packages, both with exposed thermal pad connected to GND for optimal junction-to-board thermal resistance (56 °C/W for VFQFPN8).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS62231 and ADP2302, the L6926 uniquely combines 2 V start-up, 100% duty cycle, adjustable 0.6 V output, and dual light-load modes - making it optimal for space-constrained, battery-critical portable electronics where input voltage collapse and standby current dominate design constraints.

Availability

L6926 is available at Aetrix Electronics and suitable for portable medical sensors, GPS receivers, industrial handheld terminals, and digital still cameras requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for L6926 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, specializing in power management, microcontrollers, and analog ICs for automotive, industrial, and consumer markets.

The L6926 belongs to ST's high-efficiency DC-DC converter product line, engineered specifically for battery-powered portable equipment demanding ultra-low quiescent current, wide input range, and robust protection in compact form factors.

FAQ

What is the minimum input voltage required for L6926 startup?

The L6926 starts up at a typical VCC ON threshold of 2.2 V, with 100 mV hysteresis. It continues operating down to 2.0 V, enabling full utilization of single Li-Ion cells from 4.2 V down to end-of-discharge (~2.7 V–2.8 V under load, with margin). Startup behavior is guaranteed across the -40 °C to +125 °C junction temperature range.

How does the L6926 achieve 100% duty cycle operation?

When the input voltage approaches the regulated output voltage, the internal control logic disables switching and holds the high-side MOSFET continuously on, allowing direct conduction from VIN to VOUT. This dropout mode minimizes voltage loss and maintains regulation without requiring an external LDO stage, supported by the device's current-mode architecture and valley-current limiting.

Can the PGOOD signal drive a microcontroller reset pin directly?

Yes - PGOOD is an open-drain output rated for 3.6 V max, compatible with standard 1.8 V, 3.3 V, or 5 V logic. A pull-up resistor (typically 10–100 kΩ) to VOUT or VCC is required. The signal asserts low when VOUT falls below 90% of target and releases high after recovery with 4% hysteresis, providing clean, glitch-free reset signaling without external conditioning.

Is external compensation mandatory for stable operation?

A 220 pF capacitor from COMP to GND is sufficient for stability in most applications using ceramic output capacitors. If low-ESR MLCCs cause instability (evidenced by ringing on load transients), adding a 50 kΩ series resistor to the 220 pF capacitor introduces a zero that compensates for the capacitor's high-frequency zero, restoring phase margin without altering DC regulation.