STMicroelectronics L6928Q1TR

Overview

L6928Q1TR from STMicroelectronics is a monolithic synchronous step-down DC-DC regulator in VFQFPN8 (3×3×1.0 mm) package, designed for single-cell Li-ion battery-powered systems. It delivers up to 800 mA output current with adjustable output voltage from 0.6 V, supports 2–5.5 V input range, achieves up to 95% efficiency, and features 1.4 MHz fixed-frequency current-mode control with external synchronization capability (1–2 MHz).

For engineers reviewing the L6928Q1TR datasheet, L6928Q1TR pinout, L6928Q1TR application, or L6928Q1TR equivalent, key selection criteria include low-quiescent-current operation (25 µA in low-consumption mode), 100% duty-cycle dropout support, ±1% output voltage accuracy, Power Good signaling, and dual-mode light-load control (low-noise vs. low-consumption).

Technical Context

The L6928Q1TR implements a slope-compensated current-mode PWM controller with internal high-side and low-side MOSFETs. Its architecture enables stable operation at duty cycles exceeding 50%, supports zero-crossing detection for valley-current limiting, and integrates dual protection schemes: peak current limit (1.2 A typ.) and valley current limit (1.4 A typ.) for short-circuit robustness.

Mode selection is controlled via the SYNC pin: logic-high (>1.3 V) enables discontinuous low-consumption mode (25–50 µA quiescent current); logic-low (<0.5 V) activates continuous low-noise mode (230 µA quiescent current); external clock injection (1–2 MHz) forces low-noise operation while disabling internal oscillator.

Key Specifications

Pinout & Package

VFQFPN8 (3 × 3 × 1.0 mm) package with exposed thermal pad (E-pad) requiring connection to PCB ground plane for optimal thermal performance (R_thJA = 56 °C/W). Pin 1 marked by dot; top-view pin numbering follows standard counter-clockwise layout.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down regulator applications.

Compared with TPS62231DRVR and MAX17503GCU+T, the L6928Q1TR uniquely balances ultra-low quiescent current (25 µA), Li-ion-optimized 2–5.5 V input, and 100% dropout in a 3×3 mm VFQFPN8 - making it optimal for space- and battery-life-constrained portable electronics.

Availability

L6928Q1TR is available at Aetrix Electronics and suitable for portable medical instruments, GPS navigation devices, smartphone baseband subsystems, and handheld industrial scanners requiring stable component supply across extended production lifecycles.

Supply support for L6928Q1TR 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 management ICs, sensors, and analog components for industrial, automotive, and consumer markets.

The L6928 belongs to ST's high-efficiency DC-DC converter product line, engineered specifically for battery-powered portable equipment demanding minimal quiescent current, wide input range, and robust protection in compact packages.

FAQ

What is the minimum recommended output capacitor value for stable operation?

The datasheet specifies a minimum 10 µF ceramic output capacitor with low ESR. Using X5R or X7R dielectric types rated for ≥6.3 V ensures adequate capacitance retention across temperature and bias. Lower values risk instability under load transients due to insufficient energy storage and degraded phase margin.

How does the L6928Q1TR handle short-circuit conditions?

It employs dual-stage protection: first, peak current limit (1.2 A typ.) turns off the high-side MOSFET; second, valley current limit (1.4 A typ.) prevents reactivation until inductor current decays below threshold. This prevents thermal runaway during sustained shorts while maintaining regulation during brief overloads.

Can the PGOOD pin drive a microcontroller GPIO directly?

Yes - PGOOD is an open-drain output compatible with 1.8 V, 3.3 V, or 5 V logic levels. A pull-up resistor (typically 10–100 kΩ) to the monitored rail (e.g., VOUT) is required. The pin sinks ≥4 mA when active low and leaks <50 nA when high, enabling direct interface without level-shifting.

Is external compensation mandatory for the COMP pin?

Yes - a 220 pF capacitor from COMP to GND is the baseline compensation network specified for stability across all operating conditions. For very low-ESR ceramic outputs, adding a 47–56 kΩ series resistor improves transient response and suppresses potential ringing during large load steps.