Diodes Incorporated AL5801EV1

Overview

AL5801 from Diodes Incorporated is a 100V adjustable-current-sink linear LED driver IC integrating an N-channel MOSFET and pre-biased NPN transistor in SOT26 package. It delivers up to 350mA LED current with 0.56V feedback reference, operates from 1.1V to 100V output voltage range, and supports PWM dimming via BIAS pin control - used in offline LED luminaries and signage requiring compact, inductorless constant-current drive.

For engineers reviewing the AL5801 datasheet, AL5801 pinout, AL5801 application, or AL5801 equivalent, this page provides verified technical context, thermal derating guidance, REXT-based current-setting equations, BIAS-driven PWM dimming implementation, and AEC-Q101-qualified alternatives for automotive-grade LED lighting designs.

Technical Context

The AL5801 implements a linear current-regulation architecture where the internal pre-biased NPN transistor (Q2) develops a temperature-compensated 0.56V reference across the external REXT resistor, directly controlling the gate of the integrated 100V NMOSFET (Q1). Its open-drain output stage operates in linear mode, not switching mode, eliminating need for inductors or flyback diodes.

Current regulation follows I_LED = V_RSET/R_EXT, with V_RSET exhibiting −2mV/°C temperature coefficient to reduce LED current at elevated junction temperatures. BIAS pin accepts open-collector NPN or open-drain NMOS signals for active PWM dimming, inverting duty cycle response (0% duty → max current).

Key Specifications

Pinout & Package

SOT26 package: 6-pin, surface-mount, lead-free, RoHS-compliant, with exposed copper lead frame for low thermal impedance (θ_JA down to 120°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar linear LED current sink applications.

Compared with AL5801, AL5802 offers plug-and-play simplicity at fixed current but forfeits adjustability and 100V capability; NSI45020A provides better thermal performance below 45V but cannot replace AL5801 in high-voltage or dimmable designs.

Availability

AL5801 is available at Aetrix Electronics and suitable for architectural LED strip lighting, automotive interior dome lights, and industrial panel indicator luminaires requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AL5801 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 high-reliability power management, signal integrity, and lighting solutions.

The AL5801 belongs to Diodes' linear LED driver product line, designed specifically for cost-effective, inductorless constant-current drive in space-constrained and thermally demanding applications - from automotive interiors to outdoor signage.

FAQ

What is the minimum output voltage headroom required for AL5801 to maintain regulation?

The AL5801 requires ≥1.1V between OUT and GND to sustain regulation. Below this, the internal MOSFET enters triode region and current drops nonlinearly. For a 3.2V white LED, minimum supply must be ≥3.76V (3.2V + 0.56V V_RSET) plus margin for PCB drop - typically ≥4.0V for stable 350mA operation.

Can AL5801 drive multiple parallel LED strings?

No - AL5801 regulates current in a single series path. Driving parallel strings causes current mismatch due to V_F variation, risking thermal runaway. For multi-string designs, use one AL5801 per string or select a multi-channel IC like AL8862.

How does the BIAS pin PWM dimming affect thermal performance?

At 0% duty cycle (BIAS pulled low), AL5801 delivers full current and maximum power dissipation. At 100% duty (BIAS open), output is fully off and dissipation drops to <100µW. Average power scales linearly with duty cycle, reducing self-heating proportionally - enabling higher peak currents within thermal limits.

Is AL5801 suitable for use with 100V AC rectified input?

Yes - its 100V absolute maximum output rating allows direct use with bridge-rectified 100V AC (≈140V_PK). However, peak voltage exceeds rating; a 100V-rated TVS or Zener clamp on OUT is mandatory to prevent damage during line surges or rectifier ringing.