Diodes Incorporated AL5809-50S1-7

Overview

AL5809-50S1-7 from Diodes Incorporated is a two-terminal constant current linear LED driver in SOD-123 package, delivering precisely 50mA ±5% over -40°C to +125°C with 2.5V–60V input-to-output voltage range and 20ppm/°C temperature drift. It supports both high-side and low-side LED string configurations for offline LED lamps and signage.

For engineers reviewing the AL5809-50S1-7 datasheet, AL5809-50S1-7 pinout, AL5809-50S1-7 application, or AL5809-50S1-7 equivalent, key selection criteria include fixed 50mA output accuracy, SOD-123 thermal limits (0.36W max at TA=25°C), dual-side driving capability, and PWM dimming compatibility via external MOSFET switching at the OUT terminal.

Technical Context

The AL5809-50S1-7 integrates an internal precision current mirror and low-dropout regulator to maintain stable 50mA output across 2.5V–60V V_IN-OUT, with thermal shutdown triggered at +165°C junction temperature and 30°C hysteresis. Its floating ground architecture enables direct series connection with LED strings without ground reference constraints.

It operates as a two-terminal current source: IN serves as current input (LED cathode for low-side, LED anode for high-side), while OUT serves as current output (LED anode for low-side, LED cathode for high-side). Minimum on/off pulse widths are each 500µs, supporting PWM dimming between 100Hz–200Hz with 5–95% duty cycle range.

Key Specifications

Pinout & Package

SOD-123 surface-mount package with 2.55–2.85mm body width, 1.40–1.70mm length, and 0.10–0.15mm thickness; optimized for thermal performance using 50.8mm × 50.8mm 2oz copper pad with thermal vias.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar constant current LED driver applications.

Compared with AL5809-50S1-7, the AL5809-50P1-7 offers superior thermal performance for demanding power levels, while the NSI45050AZT1G trades accuracy and protection for lower cost in benign voltage/temperature conditions.

Availability

AL5809-50S1-7 is available at Aetrix Electronics and suitable for offline LED lamps, LED signs, and white goods illumination requiring stable component supply, RoHS compliance, and SOD-123 footprint compatibility.

Supply support for AL5809-50S1-7 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 LED driver solutions for industrial and consumer markets.

The AL5809 product line delivers two-terminal constant current regulation for cost-sensitive, space-constrained LED lighting applications-designed specifically to eliminate external resistors and simplify AC/DC and DC/DC LED driver topologies.

FAQ

What is the maximum LED string voltage that AL5809-50S1-7 can drive?

The AL5809-50S1-7 supports up to 60V across its IN and OUT terminals. The maximum LED string voltage equals the input supply minus the minimum 2.5V headroom required for regulation. For example, with a 60V supply, the LED chain may be up to 57.5V (e.g., 18×3.2V white LEDs). Exceeding 60V risks permanent damage per absolute maximum ratings.

Can AL5809-50S1-7 be used in high-side configuration with common-anode LED arrays?

Yes. In high-side configuration, connect the LED array anode to the IN pin and cathode(s) to the OUT pin. This places the AL5809-50S1-7 between the positive rail and LED load, allowing direct control of common-anode topology without level-shifting circuitry. The device's floating ground design makes this possible without additional bias components.

Does AL5809-50S1-7 require a heatsink on standard FR-4 PCBs?

No dedicated heatsink is required, but thermal performance depends on PCB layout. With the recommended 50.8mm × 50.8mm 2oz copper pad and thermal vias, the SOD-123 package dissipates up to 0.36W at 25°C ambient. At higher ambient temperatures or power levels, increasing copper area and adding vias to inner ground layers is essential to maintain T_J ≤ 125°C.

Is AL5809-50S1-7 compatible with PWM dimming using microcontroller GPIO?

Yes. Drive an external N-channel MOSFET (e.g., ZXMN6A11Z) between the OUT pin and ground using a microcontroller GPIO. Apply 100–200Hz PWM with 5–95% duty cycle; the AL5809-50S1-7's 500µs minimum on/off times ensure clean current switching. Avoid frequencies above 200Hz to prevent incomplete turn-on/turn-off cycles and current instability.