STMicroelectronics L6924UTR

Overview

L6924UTR from STMicroelectronics is a monolithic linear/quasi-pulse battery charger IC for single-cell Li-Ion/Li-Polymer batteries, integrating power MOSFET, reverse-blocking diode, current-sense resistor, and thermal protection in a VFQFPN16 (3 × 3 mm) package. It supports dual-input charging (USB or AC adapter), delivers up to 1 A fast-charge current in AC mode, regulates output at 4.2 V ±1%, and implements closed-loop thermal control with NTC/PTC interface - used in compact portable devices like GPS units and digital cameras.

For engineers reviewing the L6924UTR datasheet, L6924UTR pinout, L6924UTR application, or L6924UTR equivalent, key selection criteria include input voltage range (2.5–12 V), programmable charge current (up to 1 A), thermal foldback behavior, status pin functionality (ST1/ST2 open-collector outputs), and dual-mode operation (linear vs. quasi-pulse) for optimized power dissipation in space-constrained USB-powered systems.

Technical Context

The L6924UTR operates in two distinct charging modes: linear mode when powered by regulated sources (e.g., 5 V USB or 5–12 V AC adapters), delivering precise CC/CV charging; and quasi-pulse mode when supplied by current-limited adapters, where it leverages upstream current limiting to reduce internal power dissipation. Its analog control loop directly regulates VOUT via VOSNS feedback and uses IEND for real-time current sensing (gas gauge function).

Thermal management combines junction temperature monitoring (thermal foldback activates at ~120 °C) and external thermistor interface (TH pin with programmable hot/cold thresholds relative to 1.8 V VREF). Charge termination is configurable via IEND resistor (IENDTH = 12–20 mA) and TPRG capacitor (TMAXCH = 3 h typical), with pre-charge enabled below 2.9–3.1 V battery voltage.

Key Specifications

Pinout & Package

Package: VFQFPN16 (3 mm × 3 mm, 0.5 mm pitch), thermally enhanced with exposed pad for PCB heat sinking.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar single-cell Li-Ion linear charger applications.

Compared with BQ24075RGTR and TP4056, the L6924UTR uniquely integrates quasi-pulse operation, closed-loop thermal foldback, and dual-input hardware selection - making it suitable for certified portable devices requiring robust thermal safety, flexible sourcing, and minimal external components.

Availability

L6924UTR is available at Aetrix Electronics and suitable for GPS navigation devices, USB-powered portable audio players, digital still cameras, and standalone battery chargers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for L6924UTR 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 analog, mixed-signal, power, and microcontroller solutions for industrial, automotive, and consumer markets.

The L6924UTR belongs to ST's battery management IC portfolio, engineered specifically for space-constrained portable electronics requiring integrated, thermally robust, dual-input Li-Ion charging with minimal external components.

FAQ

What input voltage ranges does the L6924UTR support, and how does it handle undervoltage conditions?

The L6924UTR operates from 2.5 V to 12 V input, with a guaranteed start-up threshold of 4.1 V. Below this, the device remains disabled and draws <90 µA in shutdown mode. If VIN drops below 2.5 V during operation, the IC enters undervoltage lockout (UVLO), halting charging and preserving battery integrity. This ensures compatibility with both standard 5 V USB and higher-voltage AC adapters while preventing erratic behavior during brownout events.

How does the quasi-pulse charging mode reduce power dissipation compared to linear mode?

In quasi-pulse mode, the L6924UTR forces the upstream adapter into current-limiting by setting I_CHG higher than the adapter's rated limit. This causes the adapter output to collapse to V_BAT + I_LIM × R_DS(on), minimizing voltage drop across the IC. Power dissipation drops from P = I_CHG × (V_IN − V_BAT) in linear mode to P ≈ I_LIM² × R_DS(on), reducing thermal load by >60% in typical 5 V/500 mA adapter scenarios.

Can the L6924UTR detect battery presence and prevent charging of faulty or missing cells?

Yes. The L6924UTR performs battery presence detection by sinking a small current from VOUT and measuring the resulting voltage at VOSNS. If VOSNS fails to rise above a threshold (indicating open-circuit or high-impedance connection), the IC enters standby mode and disables charging. This prevents damage from attempting to charge disconnected or shorted batteries and is independent of NTC thermistor connections.

What is the role of the IEND pin beyond charge termination, and how accurate is its current-sensing function?

The IEND pin provides an analog voltage proportional to the instantaneous charge current (V_IEND = I_CHG × R_END), serving as a real-time gas gauge. With ±7% accuracy over temperature and line regulation, it enables host MCUs to compute state-of-charge without external shunt amplifiers. For example, a 3.3 kΩ resistor yields 16 mV/mA, allowing 12-bit ADCs to resolve ~10 mA changes in 0–1 A range.