STMicroelectronics L6920DC

Overview

L6920DC from STMicroelectronics is a monolithic synchronous rectifier step-up DC/DC converter IC designed for low-voltage battery-powered systems. It starts up at 0.8V input, delivers adjustable output from 1.8V to 5.5V (or fixed 3.3V/5V), integrates internal MOSFETs with 300mΩ R_DS(on), and operates up to 1MHz switching frequency-enabling compact PDA, digital camera, and GPS power supplies.

For engineers reviewing the L6920DC datasheet, L6920DC pinout, L6920DC application, or L6920DC equivalent, key selection criteria include startup voltage (0.8V), synchronous rectification architecture, low-battery detection interface (LBI/LBO), reverse polarity protection, and MSOP8 footprint constraints in space-constrained portable designs.

Technical Context

The L6920DC uses a constant-frequency PWM control scheme with programmable maximum on-time (5µs typ.) and minimum off-time (1µs typ.), enabling stable regulation across light-to-heavy loads. Its internal charge pump drives the N-channel main switch gate, allowing efficient operation down to 0.8V input without external bias circuitry.

It integrates a 1.23V reference, open-drain low-battery output (LBO), shutdown control (SHDN), and reverse-polarity protection that limits reverse current to <1µA. The FB pin supports three configurations: direct connection to GND (5V), OUT (3.3V), or external resistor divider (1.8–5.5V).

Key Specifications

Pinout & Package

Package: MSOP8 (3.0mm × 4.9mm, 0.65mm pitch), RoHS-compliant ECOPACK® with lead-free interconnect.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-up converter applications.

Compared with TPS61200 and ADP1612, the L6920DC uniquely combines ultra-low 0.8V start-up, integrated reverse polarity blocking, and dedicated LBI/LBO battery monitoring-all in an MSOP8 package-making it optimal for space- and battery-life-constrained single-cell portable devices.

Availability

L6920DC is available at Aetrix Electronics and suitable for PDA power management, digital camera core supply, and GPS module supply requiring stable component supply across long-lifecycle consumer electronics programs.

Supply support for L6920DC 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 industrial, automotive, and consumer markets.

The L6920DC belongs to ST's low-voltage DC/DC converter product line, engineered specifically for ultra-low-input, battery-powered portable equipment where start-up voltage, quiescent current, and integration density are critical.

FAQ

What is the minimum input voltage required for L6920DC to start switching?

The L6920DC begins switching at 0.8V input voltage under typical conditions (V_OUT = 3.3V). This is verified in Figure 4 of the datasheet and confirmed by test data showing functional start-up down to 0.78V at light load. Operation continues until input drops below this threshold, making it suitable for single-cell alkaline, NiMH, or Li-ion applications nearing end-of-discharge.

How is the low-battery detection threshold set on the L6920DC?

The L6920DC uses an internal 1.23V comparator reference for low-battery detection. The user sets the actual battery voltage threshold by connecting a resistor divider between V_IN and GND, feeding the midpoint to the LBI pin. Equation 2 in the datasheet defines the relationship: V_batt-th = 1.23V × (1 + R1/R2), where R1 is the upper resistor and R2 the lower resistor.

Does the L6920DC require an external Schottky diode?

No. The L6920DC integrates both the main N-channel switch and synchronous P-channel rectifier, eliminating the need for an external Schottky diode. This reduces conduction losses, improves efficiency by up to 8% at medium loads, and saves PCB area-confirmed by efficiency curves in Figures 2 and 3 showing peak >90% at 100mA with 10µH inductor.

What is the function of the REF pin, and how should it be decoupled?

The REF pin outputs the internal 1.23V bandgap reference used for feedback regulation and LBI comparison. It must be bypassed to GND with a 100nF ceramic capacitor to suppress high-frequency noise; the datasheet explicitly states "no capacitor is required for stability" but confirms noise filtering is essential for accurate low-battery detection and output regulation accuracy.