Diodes Incorporated AL8871QEV1

Overview

AL8871QEV1 from Diodes Incorporated is an evaluation board for the AL8871Q buck-boost LED driver IC, configured to drive up to 5 LEDs at 680mA from a 5.4–30V DC input. It provides PWM (inverted), DC, and NTC thermal dimming interfaces, along with monitoring points for FAULT, STATUS, LX, BST, and LED terminals.

For engineers reviewing the AL8871QEV1 datasheet, AL8871QEV1 pinout, AL8871QEV1 application, or AL8871QEV1 equivalent, this board supports rapid validation of AL8871Q-based lighting designs requiring flexible dimming control, conducted EMC filtering, and low-VIN bootstrap operation down to 5V.

Technical Context

The AL8871QEV1 implements a synchronous buck-boost topology using the AL8871Q IC (TSSOP-16EP), DMN6068LK3 high-side MOSFET, and DFLS140 Schottky bootstrap diode. It supports three independent dimming paths: inverted PWM (100–500 Hz), analog CTRL (0.125–1.25 V), and NTC-based thermal foldback (~70°C trip with 10kΩ NTC + 1.8kΩ R7).

Key circuit features include configurable bootstrap (R3/R4 removable), LX switching node access for waveform analysis, and dedicated test points for FAULT/STATUS logic-level monitoring. The board delivers regulated constant current under input voltage variations spanning 5.4V to 30V, with output voltage headroom sufficient for 5-LED strings approaching 50V total forward drop.

Key Specifications

Availability

AL8871QEV1 is available at Aetrix Electronics and suitable for LED lighting development, automotive interior lighting prototyping, and industrial status indicator validation requiring stable component supply and repeatable reference design implementation.

Supply support for AL8871QEV1 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 lighting solutions for industrial, consumer, and automotive markets.

The AL8871QEV1 belongs to Diodes' LED driver evaluation platform family, designed to accelerate adoption of their AL8871Q buck-boost controller in applications demanding wide-input-voltage operation and multi-mode dimming.

FAQ

What is the purpose of the inverted PWM input on AL8871QEV1?

The PWM̅̅̅̅̅̅̅̅ input is hardware-inverted to enable wire-OR connection with the overvoltage protection circuit. This allows safe dimming control while preserving fault response integrity. Users must apply active-low PWM signals between 100 Hz and 500 Hz for optimal current linearity and minimal audible noise.

How do I enable DC dimming on the AL8871QEV1 board?

To enable DC dimming, remove resistor R8 and apply a 0.125–1.25 V analog voltage to the CTRL terminal. This voltage linearly scales the 680 mA output current from 0% to 100%. The board's default configuration disables DC dimming via R8 shorting CTRL to ground.

Can the AL8871QEV1 operate below 5.4V input?

No - the minimum specified input is 5.4V per the AL8871Q datasheet. However, with R4 removed and R3 fitted as 0Ω, the board can be reconfigured for non-bootstrapped operation, though output current regulation and LED count capability degrade below 5.4V due to internal gate drive limitations.

What is the function of the BST test point on AL8871QEV1?

The BST test point provides direct access to the AL8871Q's bootstrap capacitor node. It allows measurement of the gate-drive auxiliary supply voltage and enables external BST sourcing if R3 and R4 are removed. With R4 installed, BST is generated via D2 and LX, supporting low-VIN operation down to ~5V.