Diodes Incorporated AL8853AQS-13

Overview

AL8853AQS-13 from Diodes Incorporated is an AEC-Q100 Grade 1 qualified automotive boost/SEPIC LED controller in SO-8 package, delivering fixed 400kHz current-mode PWM regulation with 200mV ±3% feedback reference, 6–40V input range, and comprehensive fault protection including OCP, OVP, OTP, LED open/cathode-short, and diode-inductor short detection. It enables constant-current LED lighting for headlamps and DRLs.

For engineers reviewing the AL8853AQS-13 datasheet, AL8853AQS-13 pinout, AL8853AQS-13 application, or AL8853AQS-13 equivalent, this controller supports PWM-to-analog dimming (5–50kHz), features cycle-by-cycle current sensing via external resistor, integrates slope compensation to prevent sub-harmonic oscillation above 50% duty, and provides latch-off protection with COMP-pin monitoring and OVP-pin startup validation for SEPIC/boost topologies.

Technical Context

The AL8853AQS-13 implements peak current-mode control with internal transconductance error amplifier (70dB open-loop gain, 100µA/V gm) and fixed-frequency oscillator (360–430kHz). Its PWM comparator compares slope-compensated CS signal against EA output to determine GATE on-time, enabling stable regulation across wide VIN (6–40V) and temperature (−40°C to +125°C).

Startup is enabled by >2.5V on PWM pin; UVLO activates at 5.4V (rising) with 400mV hysteresis. OVP pin monitors output voltage with dual thresholds: 200mV for normal operation and 100mV for SEPIC startup offset. COMP pin serves as loop compensation node and also triggers latched shutdown if held >3.2V for 37ms during LED-cathode-to-GND fault.

Key Specifications

Pinout & Package

AL8853AQS-13 is housed in a Pb-free, RoHS-compliant SO-8 package (5.0mm × 6.0mm, 1.25mm height) with standard gull-wing leads and exposed thermal pad (connected to GND internally).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPQ4425AGL-A and LM3410XMF/NOPB, the AL8853AQS-13 uniquely combines AEC-Q100 Grade 1 qualification, 40V input tolerance, SEPIC/boost dual-mode support, and multi-layer fault latching-making it the only choice for thermally demanding, safety-critical automotive exterior lighting where system-level reliability outweighs integration convenience.

Availability

AL8853AQS-13 is available at Aetrix Electronics and suitable for automotive headlamps, daytime running lights, and infotainment backlighting requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AL8853AQS-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 analog ICs, specializing in high-reliability components for automotive, industrial, and consumer markets with IATF 16949-certified facilities.

The AL8853AQS-13 belongs to Diodes' automotive LED controller product line, engineered specifically for cost-effective, robust constant-current lighting in harsh environments-emphasizing fault resilience, wide-input operation, and seamless integration into AEC-Q100-compliant vehicle systems.

FAQ

What is the minimum PWM frequency supported for analog dimming?

The AL8853AQS-13 supports PWM dimming inputs from 5 kHz to 50 kHz. At 5 kHz, the internal filter produces stable analog reference voltage for the error amplifier; frequencies below 5 kHz cause visible ripple in LED current regulation and may trigger false OCP events due to insufficient averaging. The IC does not support DC dimming or 0 Hz input.

How is SEPIC topology initialized given the OVP pin's low-voltage startup requirement?

During SEPIC startup, the OVP pin sees near-zero voltage before regulation begins. To avoid premature OVP shutdown, a 0.2V DC offset must be applied to the OVP pin-typically implemented with a resistor divider from VIN or a small bias current source. This ensures the IC recognizes valid startup conditions and enables GATE drive before output voltage builds.

Does the AL8853AQS-13 require external slope compensation in all designs?

No-internal slope compensation suffices for most boost designs with duty cycles ≤50%. External slope compensation (via resistor RSL in series with CS) is required only when duty cycle exceeds 50%, such as in high-VIN/low-VOUT boost or SEPIC configurations. Adding unnecessary RSL degrades current-sense accuracy and loop response.

What happens during LED open-circuit failure and how is recovery handled?

Upon LED open, output voltage rises until the OVP pin detects >2.0V, triggering immediate GATE shutdown and COMP capacitor discharge. Recovery occurs automatically when OVP voltage falls below 100mV hysteresis-either after fault removal or through VIN cycle. No external reset is needed, but PWM must remain active to re-enable operation.