Diodes Incorporated AL8400QEV1

Overview

AL8400QEV1 from Diodes Incorporated is a double-sided evaluation board for the AL8400Q 5-terminal linear LED driver IC, preset to deliver 150mA constant current to LED strings with total forward voltage up to 18V. It supports input voltage range of 4–18VDC, uses a 1.3Ω sense resistor (R2), and lacks reverse supply protection.

For engineers reviewing the AL8400QEV1 datasheet, AL8400QEV1 pinout, AL8400QEV1 application, or AL8400QEV1 equivalent, this board enables rapid validation of AL8400Q-based constant-current LED driver designs-particularly for instrumentation backlighting, signage, and isolated offline converters requiring precise current regulation and thermal stability across –40°C to +125°C.

Technical Context

The AL8400QEV1 implements a constant-current feedback loop using the AL8400Q's 0.2V FB reference to regulate LED current via external NPN transistor Q1 (FZT690B) and sense resistor R2. The board's schematic fixes R2 at 1.3Ω, yielding nominal I_LED = 0.2V / 1.3Ω ≈ 154mA, with ±6.5% variation due to device tolerance (±5%) and resistor tolerance (±1%).

Vin is routed to the AL8400Q's VCC pin through a 0.47μF ceramic capacitor, while OUT drives Q1's base. GND and E1 are tied together as analog and emitter ground. The board allows extended-voltage operation by tapping Vin from an intermediate point in the LED string-bypassing AL8400Q's 18V VCC limit.

Key Specifications

Availability

AL8400QEV1 is available at Aetrix Electronics and suitable for LED signage development, instrumentation backlighting validation, and isolated offline LED converter prototyping requiring stable component supply and traceable evaluation hardware.

Supply support for AL8400QEV1 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 analog ICs, specializing in power management, signal integrity, and lighting solutions for industrial, automotive, and consumer applications.

The AL8400QEV1 belongs to Diodes' LED driver evaluation platform family, designed to accelerate adoption of their high-accuracy, low-V_FB linear controllers in thermally demanding, space-constrained constant-current lighting systems.

FAQ

What is the purpose of the AL8400QEV1 evaluation board?

The AL8400QEV1 is a ready-to-use hardware platform for evaluating the AL8400Q linear LED driver IC. It demonstrates constant-current regulation using an external NPN transistor and 1.3Ω sense resistor, enabling quick validation of LED string drive performance, thermal behavior, and layout considerations without custom PCB design.

Can the AL8400QEV1 drive LED strings exceeding 18V total forward voltage?

Yes-by tapping the Vin connection from an intermediate node in the LED string instead of the full string anode, the AL8400Q's 18V VCC rating is bypassed. This extends usable input voltage beyond 18V while maintaining 0.2V FB regulation and 150mA current setting, provided the external transistor and layout support higher voltage isolation.

Why does the board lack reverse supply protection?

The AL8400QEV1 omits reverse-polarity protection circuitry to preserve signal integrity, minimize voltage drop across the sense path, and avoid introducing parasitic elements that could affect current regulation accuracy or thermal response-consistent with its role as a reference design for engineering validation rather than end-product deployment.

How is LED current accuracy affected on the AL8400QEV1?

LED current accuracy depends on AL8400Q's ±5% FB voltage tolerance over temperature and R2's ±1% resistance tolerance. With nominal 0.2V/1.3Ω = 154mA, worst-case current ranges from 144mA to 163mA (±6.5%), verified in the reference design documentation and confirmed by circuit analysis in the user guide.