Diodes Incorporated AL8861QEV1

Overview

AL8861QEV1 from Diodes Incorporated is an automotive-grade LED driver evaluation board based on the AL8861Q hysteresis-mode DC-DC buck converter IC. It supports 4.5–40V input, delivers up to 1.5A adjustable LED current, integrates a 40V NDMOS switch, and enables analog/PWM dimming via the VSET pin for driving 1–10 series LEDs in vehicle lighting systems.

For engineers reviewing the AL8861QEV1 datasheet, AL8861QEV1 pinout, AL8861QEV1 application, or AL8861QEV1 equivalent, this board provides validated reference design, functional waveforms (startup, soft-start, PWM/analog dimming), protection behavior (LED open/short), efficiency curves, and BOM with Diodes' qualified components including AL8861QSP-13, B240AQ-13-F, and SMAJ40A.

Technical Context

The AL8861QEV1 implements a fixed-frequency hysteresis-controlled buck topology using the AL8861Q IC, which integrates a high-side power switch and current-sense circuitry. Input voltage range (4.5–40V) and output current (up to 1.5A) are set by external resistors R1/R2 and inductor L1 (68µH).

VSET pin functionality unifies on/off control, analog dimming (0.3–2.5V), and PWM dimming (100Hz–1kHz, 1–100% duty), with soft-start time adjusted via capacitor C4. Protection features include LED open-circuit detection, LED short-circuit limiting, and thermal shutdown - all verified on this PCB layout.

Key Specifications

Availability

AL8861QEV1 is available at Aetrix Electronics and suitable for automotive interior lamps, exterior lamps, and LED headlamp module development requiring stable component supply, PPAP-ready reference designs, and AEC-Q100 Grade 1 validated performance.

Supply support for AL8861QEV1 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and integrated circuits, specializing in power management, signal integrity, and protection solutions for automotive, industrial, and consumer markets.

The AL8861QEV1 belongs to Diodes' automotive LED driver evaluation platform family, designed to accelerate qualification of AEC-Q100-compliant lighting systems with validated thermal, electrical, and protection behavior.

FAQ

What is the purpose of the VSET pin on the AL8861QEV1 board?

The VSET pin serves three functions: enabling analog dimming (0.3–2.5V input adjusts LED current from 5% to 100%), accepting PWM signals (100Hz–1kHz, low <0.3V/high >2.5V) for brightness control, and turning off output when voltage drops ≤0.2V to enter low-power standby mode.

How is LED current set on the AL8861QEV1?

LED current is set by parallel resistors R1 (0.1Ω) and R2 (0.2Ω), yielding 0.067Ω total sense resistance. With AL8861Q's internal 0.1V current-sense reference, this configures nominal 1.5A output (I_LED = 0.1V / 0.067Ω). R1/R2 values are confirmed in the BOM on page 5 of the User Guide.

Does the AL8861QEV1 support both analog and PWM dimming simultaneously?

No - analog and PWM dimming are mutually exclusive modes selected by hardware configuration. For analog dimming, a 100nF capacitor is installed at C3; for PWM, C3 is removed and the signal is applied directly to VSET. The board does not support concurrent or mixed-signal dimming per the User Guide's Quick Start instructions.

What protection features are demonstrated on the AL8861QEV1?

The board demonstrates LED open-circuit protection (output shuts down if no LED path detected), LED short-circuit protection (limits current during cathode-to-ground fault), and overtemperature shutdown (thermal foldback verified in functional waveforms on page 7). These behaviors are inherent to the AL8861Q IC and validated on this PCB layout.