STMicroelectronics STEVAL-ILL039V2

Overview

STEVAL-ILL039V2 from STMicroelectronics is a demonstration board implementing a step-up LED current controller for driving four 300 mA LEDs using the STLDC08 constant-current DC-DC controller IC. It operates from 0.8 V to 3.6 V input (e.g., single or dual alkaline/AAA batteries), supports external PWM dimming, and regulates LED current via a precision 100 mV FB-sense voltage across an external resistor.

For engineers reviewing the STEVAL-ILL039V2 datasheet, STEVAL-ILL039V2 pinout, STEVAL-ILL039V2 application, or STEVAL-ILL039V2 equivalent, key considerations include input voltage range compatibility with battery-powered portable lighting, PWM dimming interface timing requirements, PCB layout constraints for boost converter stability, and thermal management of the STLDC08 in high-current LED drive configurations.

Technical Context

The board implements a fixed-frequency, current-mode boost converter topology centered on the STLDC08 IC, which integrates an internal 0.5 A switch and feedback comparator. Regulation is achieved by maintaining 100 mV across the external sense resistor connected between FB and GND, enabling precise 300 mA per-string current control independent of forward voltage variation among the four LEDs.

Input voltage support down to 0.8 V enables operation from partially discharged AA/AAA cells, while the external PWM dimming input allows direct digital brightness control without altering the regulated current loop - preserving color consistency and efficiency across dimming levels.

Key Specifications

Availability

STEVAL-ILL039V2 is available at Aetrix Electronics and suitable for portable lighting design validation, battery-powered LED flashlight development, and handheld medical device illumination requiring stable component supply and rapid prototyping capability.

Supply support for STEVAL-ILL039V2 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, specializing in microcontrollers, power management, analog, and sensor solutions for industrial, automotive, and consumer applications.

The STEVAL series comprises ST's official evaluation and demonstration platforms, designed to accelerate customer adoption of ST ICs by providing validated reference designs, schematics, layout files, and firmware examples for real-world use cases.

FAQ

What is the primary function of the STEVAL-ILL039V2 board?

The STEVAL-ILL039V2 is a demonstration board that implements a step-up LED driver solution using the STLDC08 IC to deliver a regulated 300 mA current to four parallel LEDs from low-voltage battery sources (0.8–3.6 V). It is not a standalone IC but a fully assembled, tested hardware platform for evaluating boost-based LED current control.

Can the board drive LEDs with different forward voltages?

Driving LEDs with significantly mismatched forward voltages in parallel risks current imbalance and thermal runaway. The board assumes matched LEDs or uses separate current paths; its regulation relies on a shared sense resistor, so V_F variation directly impacts per-LED current distribution without additional balancing circuitry.

What is the role of the FB pin on the STLDC08 in this design?

The FB pin senses voltage across the external current-sense resistor. The STLDC08's internal error amplifier maintains 100 mV at this pin, thereby regulating LED current to I_LED = 100 mV / R_sense. On STEVAL-ILL039V2, this sets I_LED = 300 mA when R_sense = 330 mΩ, as confirmed in the schematic and data brief.

Is the STEVAL-ILL039V2 RoHS compliant?

Yes, the STEVAL-ILL039V2 board is RoHS compliant, as explicitly stated in the STMicroelectronics data brief (Doc ID 018913 Rev 1). All components and PCB fabrication meet EU Directive 2011/65/EU requirements for restriction of hazardous substances.