STMicroelectronics STLUX285A

Overview

STLUX285A from STMicroelectronics is a digital lighting and power conversion controller integrating an STM8® core, six autonomous SMED PWM generators (1.3 ns resolution), DALI 2.0-compliant interface, four 50 ns comparators, and 10-bit ADC with op-amp gain options. It targets high-precision LED/HID ballast control and resonant SMPS topologies requiring event-driven timing.

For engineers reviewing the STLUX285A datasheet, STLUX285A pinout, STLUX285A application, or STLUX285A equivalent, this device is selected for time-critical digital power control where sub-10 ns event response, hardware DALI encoding, and zero-current detection via fast comparators are required.

Technical Context

The STLUX285A implements six independent SMED (State Machine Event Driven) units-each a fully autonomous finite-state machine reacting to internal timers, comparator outputs, DIGIN signals, or software events in ≤10.4 ns. Each SMED supports IDLE/S0–S3/HOLD states, configurable transition triggers, and dithered 1.3 ns PWM resolution via its 96 MHz PLL clock domain.

Its integrated STM8 core (16 MHz max CPU, Harvard architecture, 3-stage pipeline) configures SMEDs, manages DALI frame encoding/decoding per IEC 62386, sequences up to 8-channel ADC conversions with x1/x4 programmable gain, and executes real-time protection logic using four analog comparators with 4-bit internal references and <50 ns propagation delay.

Key Specifications

Pinout & Package

STLUX285A is housed in a TSSOP38 package (38-pin thin shrink small outline package) with 0.65 mm pitch, exposing dedicated SMED output pins (PWM0–PWM5), six fast digital inputs (DIGIN0–DIGIN5), four comparator positive inputs (CP0–CP3), one shared negative input (CMPN), DALI TX/RX lines, UART, SWIM debug, and GPIO with current-injection immunity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digital lighting and power conversion controller applications.

Compared with STLUX325A and STLUX385A, the STLUX285A provides the optimal balance of full 6-SMED I/O capability in TSSOP38 packaging without added peripherals-making it ideal for cost-sensitive, space-constrained digital ballasts where I²C is unused and all six PWM outputs are required.

Availability

STLUX285A is available at Aetrix Electronics and suitable for LED dimming systems, HID electronic ballasts, digital PFC+LLC power supplies, and synchronous rectifier controllers requiring stable component supply across industrial production cycles.

Supply support for STLUX285A 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power ICs, sensors, and analog devices for industrial, automotive, and consumer markets.

The STLUX family is engineered specifically for digital lighting and switched-mode power conversion, combining deterministic real-time PWM control with standards-compliant communication and robust analog signal conditioning.

FAQ

What is the maximum achievable PWM frequency using SMED dithering on STLUX285A?

The STLUX285A's SMED units operate from a 96 MHz PLL clock. With dithering enabled, the effective PWM resolution reaches 1.3 ns, allowing theoretical frequencies up to ~769 MHz for single-edge toggling. In practical lighting and power applications, typical configured frequencies range from 100 kHz to 1 MHz, constrained by external MOSFET gate charge and layout parasitics-not by the SMED itself.

Does STLUX285A support DALI-2 commands such as scene recall or group addressing?

Yes. The hardware DALI peripheral complies fully with IEC 62386-102 (DALI-2), supporting all mandatory and optional commands including scene storage/recall (commands 128–135), group addressing (command 256+), fade time configuration (command 112), and extended 24-bit frame formats. No firmware modification is needed-the encoder handles frame assembly and timing automatically.

Can the four analog comparators be used simultaneously for independent overcurrent protection on four power phases?

Yes. All four comparators operate concurrently with independent positive inputs (CP0–CP3) and a shared negative input (CMPN). Each comparator generates a dedicated interrupt and can trigger SMED state transitions directly via the connection matrix-enabling simultaneous, cycle-by-cycle overcurrent cutoff across four isolated power legs without CPU involvement.

Is the STLUX285A pin-compatible with STLUX325A or STLUX385A?

No. Although STLUX285A and STLUX385A share the TSSOP38 package and identical pin count, their pin assignments differ-particularly for SMED outputs, DIGIN mapping, and peripheral functions. STLUX325A uses VFQFPN32 and has only 32 pins. Direct replacement requires PCB redesign; migration must follow official ST pinout diagrams and register-level initialization updates.