STMicroelectronics L6928Q1

Overview

L6928Q1 from STMicroelectronics is a monolithic synchronous step-down DC-DC regulator in VFQFPN8 (3×3×1.0 mm) package, designed for single Li-Ion battery-powered systems. It delivers up to 800 mA output current with adjustable 0.6 V–5.5 V output, 1.4 MHz fixed switching frequency, ±1% output voltage accuracy, and 100% duty-cycle low-dropout operation.

For engineers reviewing the L6928Q1 datasheet, L6928Q1 pinout, L6928Q1 application, or L6928Q1 equivalent, key selection criteria include its 2–5.5 V input range, internal synchronous MOSFETs eliminating external Schottky diodes, selectable low-noise/low-consumption light-load modes, Power Good signal, and 1 µA shutdown current - critical for portable instrumentation and handheld terminals.

Technical Context

The L6928Q1 employs a current-mode PWM control architecture with slope compensation to ensure stability at >50% duty cycles. Its dual-mode operation - low-noise (1.4 MHz continuous switching) and low-consumption (discontinuous conduction at light load) - is selected via the SYNC pin voltage threshold (1.3 V high / 0.5 V low).

It integrates overvoltage protection (10% above VREF), thermal shutdown at 150 °C, short-circuit protection with peak (1.2 A typ.) and valley (1.4 A typ.) current limits, and an open-drain PGOOD comparator monitoring VFB at 90% of 0.6 V reference.

Key Specifications

Pinout & Package

VFQFPN8 package (3 mm × 3 mm × 1.0 mm, exposed thermal pad) provides low thermal resistance (R_thJA = 56 °C/W) and optimal PCB heat dissipation when E-pad is soldered to GND plane.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS62231DRVR and MAX17503GCU+T, the L6928Q1 uniquely balances Li-Ion input compatibility (2–5.5 V), integrated PGOOD, external sync capability, and dual-mode light-load optimization - making it optimal for portable instrumentation demanding both runtime and noise performance.

Availability

L6928Q1 is available at Aetrix Electronics and suitable for portable medical sensors, GPS navigation modules, industrial handheld terminals, and wireless IoT edge nodes requiring stable component supply across long-lifecycle embedded programs.

Supply support for L6928Q1 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/mixed-signal ICs for automotive, industrial, and consumer markets.

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

FAQ

What is the minimum input voltage required for L6928Q1 startup?

The L6928Q1 requires a minimum input voltage of 2.2 V (typical) to initiate startup due to its internal UVLO circuit. Once running, it continues operation down to 2.0 V input, supporting deep discharge of Li-Ion batteries. The 100 mV hysteresis prevents oscillation during voltage sags.

How does the SYNC pin affect light-load efficiency and noise?

When SYNC is pulled high (>1.3 V), the device enters low-consumption mode, skipping switching cycles to maintain regulation with only 25 µA quiescent current - ideal for battery runtime. When SYNC is low (<0.5 V), it operates in low-noise mode at fixed 1.4 MHz, minimizing audible noise and EMI but drawing 230 µA at no load.

Can L6928Q1 operate without an external compensation network on the COMP pin?

No - the COMP pin requires an external RC compensation network (e.g., 220 pF capacitor to GND) to stabilize the current-mode control loop. Omitting it risks instability, especially under high-duty-cycle or fast-transient conditions. ST recommends adding a 50 kΩ series resistor if using ultra-low-ESR ceramic output capacitors.

What thermal considerations apply to the VFQFPN8 package of L6928Q1?

The VFQFPN8 package has R_thJA = 56 °C/W, significantly lower than TSSOP8 (180 °C/W). To achieve this, the exposed E-pad must be soldered to a solid GND copper pour with ≥4 thermal vias. Without proper thermal anchoring, junction temperature rise exceeds safe limits under 800 mA load, triggering thermal shutdown at 150 °C.