Diodes Incorporated AL1665S-13

Overview

AL1665S-13 from Diodes Incorporated is a high-performance primary-side regulation (PSR) LED controller for dimmable flyback and buck-boost topologies, delivering accurate constant-current regulation without optocoupler or secondary feedback. It operates in boundary conduction mode (BCM), achieves >0.9 power factor and <20% THD under universal input, supports analog (5–100%) and PWM (0.5–100% at 1 kHz) dimming, and integrates full protection including UVLO, OVP, OSP, OCP, winding/secondary diode short detection, thermal foldback, and OTP.

For engineers reviewing the AL1665S-13 datasheet, AL1665S-13 pinout, AL1665S-13 application, or AL1665S-13 equivalent, this device serves as a cost-optimized, single-stage AC/DC LED driver IC targeting stable current regulation, EMI-sensitive lighting systems, and thermally constrained smart lighting designs requiring programmable thermal management and dual-dimming interface support.

Technical Context

The AL1665S-13 implements valley-switching quasi-resonant control to minimize switching loss and EMI while maintaining high efficiency across universal AC input (85–265 VAC). Its PSR architecture samples reflected auxiliary winding voltage (FB pin) and primary-side current sense (CS pin) to regulate output current without secondary-side components.

It features dual-function NTC/PWM pin supporting either NTC-based thermal foldback (with user-programmable start/stop thresholds: VTF(START) = 1.00 V, VTF(STOP) = 0.69 V) or external PWM dimming signal, and an ADIM pin accepting 0.05–2.5 V DC for analog dimming with ±1.5% internal 0.4 V CS reference precision.

Key Specifications

Pinout & Package

AL1665S-13 is housed in an SO-8 (Standard) package with exposed pad not electrically connected. Pin assignments are validated per Diodes DS41772 Rev. 3-2.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED controller applications.

Compared with NCL30086 and ICE2QS03G, the AL1665S-13 uniquely combines PSR, dual-mode dimming, and programmable thermal foldback in SO-8 - reducing component count by ≥6 and enabling direct NTC integration without signal conditioning.

Availability

AL1665S-13 is available at Aetrix Electronics and suitable for smart residential LED drivers, commercial dimmable troffer drivers, industrial high-bay lighting, and outdoor streetlight drivers requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for AL1665S-13 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 ICs, specializing in high-reliability power management, signal integrity, and lighting solutions for industrial, automotive, and consumer markets.

The AL1665S-13 belongs to Diodes' high-performance LED controller product line, designed specifically for cost-sensitive, thermally demanding, dimmable AC/DC LED lighting applications requiring PSR, dual dimming modes, and comprehensive fault protection.

FAQ

What dimming interfaces does AL1665S-13 support, and what are their respective ranges?

The AL1665S-13 supports analog dimming via the ADIM pin (0.05–2.5 V DC, corresponding to 5–100% LED current) and PWM dimming via the NTC/PWM pin (0.5–100% duty cycle at 1 kHz). Analog dimming provides smooth, flicker-free control ideal for residential settings, while PWM dimming enables precise digital control compatible with building automation systems. Both interfaces operate independently and do not require external logic.

How does the AL1665S-13 achieve primary-side regulation without an optocoupler?

The AL1665S-13 achieves PSR by sampling the reflected voltage from the transformer's auxiliary winding at the FB pin and correlating it with primary-side current sensed at the CS pin. Using internal timing and valley detection, it calculates output current based on the discharge time of the secondary winding and the known turns ratio. This eliminates the need for optocouplers, TL431 references, or secondary-side feedback components.

What thermal protection mechanisms are implemented, and how do they differ?

The AL1665S-13 implements two distinct thermal protections: thermal foldback (TFP) and overtemperature protection (OTP). TFP gradually reduces LED current to 50% as the NTC/PWM pin voltage drops below 1.00 V, allowing continued operation at reduced brightness. OTP triggers at +180°C junction temperature, forcing a full shutdown with latch-off behavior until the NTC/PWM pin voltage rises above 0.70 V, ensuring safe cooldown before restart.

Can AL1665S-13 be used in both flyback and buck-boost topologies, and what design changes are required?

Yes - the AL1665S-13 supports both flyback and buck-boost topologies using the same IC. For flyback, the FB pin senses auxiliary winding voltage; for buck-boost, FB senses output voltage directly via resistive divider. The key difference is transformer configuration: flyback requires isolation and auxiliary winding, while buck-boost uses non-isolated inductor and direct output sensing. External component values (RCS, R_COMP, C_COMP) must be recalculated per topology per the datasheet design equations.