Allegro MicroSystems A6280EA-T

Overview

A6280EA-T from Allegro MicroSystems is a 3-channel constant-current LED driver IC designed for RGB pixel control in large-character signage and architectural lighting. It delivers programmable 10-bit PWM brightness (0–1023 levels per channel), 7-bit dot correction per output, and supports 10–150 mA output current per channel via external R_EXT. Its daisy-chain architecture enables scalable control of hundreds of LEDs using only four logic signals.

For engineers reviewing the A6280EA-T datasheet, A6280EA-T pinout, A6280EA-T application, or A6280EA-T equivalent, this page provides verified technical context on its 16-pin DIP package, thermal shutdown (165°C), undervoltage lockout (3.0–4.5 V), buffered serial interface (up to 5 MHz), and role in high-fidelity color-matched LED clusters requiring precise current regulation and timing-synchronized data propagation.

Technical Context

The A6280EA-T implements a 31-bit shift register with address-selectable loading of either 10-bit PWM counters or 7-bit dot correction scalars-enabling single-pin sharing of serial clock (CI) and PWM clock functionality. Its internal linear regulator allows VIN to be tied directly to the LED supply bus (5–17 V), eliminating external regulators.

Each of the three sinking outputs features independent 10-bit brightness control and 7-bit current scaling, with output-to-output matching error ≤ ±7% at full scale. Buffered CO/LO/OEO/SDO outputs support daisy-chained topologies up to 250 devices, with 100 ns one-shot clock output timing ensuring signal integrity across long Cat5 UTP runs.

Key Specifications

Pinout & Package

Package: 16-pin plastic dual in-line package (DIP), lead-free with 100% matte-tin plating; R_θJA = 38°C/W on 4-layer PCB.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-channel constant-current LED driver applications.

Compared with TLC59283DBQR and MAX7219CNG+, the A6280EA-T uniquely combines per-channel dot correction, shared R_EXT current setting, and buffered daisy-chain outputs-making it optimal for large-scale, color-critical LED signage where luminance uniformity and wiring simplicity are design priorities.

Availability

A6280EA-T is available at Aetrix Electronics and suitable for colored large-character LED signs, architectural lighting systems, and scrolling marquee applications requiring stable component supply despite its Last Time Buy status.

Supply support for A6280EA-T 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

Allegro MicroSystems, LLC is a U.S.-based designer and manufacturer of high-performance magnetic sensors and power ICs, headquartered in Worcester, Massachusetts.

The A6280 product line was developed specifically for scalable, high-fidelity LED display systems-emphasizing daisy-chain reliability, per-channel current matching, and simplified power architecture for outdoor and architectural lighting.

FAQ

What is the function of the REXT pin on the A6280EA-T?

The REXT pin on the A6280EA-T connects to an external resistor tied to LGND and sets the global maximum output current for all three channels using the formula I_OUT(max) = 753.12 / R_EXT. For example, a 5 kΩ resistor yields ~150 mA per channel. This resistor establishes the current reference for both PWM brightness scaling and dot correction, ensuring consistent regulation across temperature and supply variations. The A6280EA-T does not regulate current without this resistor.

How does the A6280EA-T achieve daisy-chain synchronization across many devices?

The A6280EA-T achieves daisy-chain synchronization through buffered, matched-propagation outputs: CO drives the next CI, LO drives the next LI, OEO drives the next OEI, and SDO drives the next SDI. Each CO output is driven by a 100 ns one-shot circuit triggered on the CI rising edge, preserving clock duty cycle integrity. The LI-to-LO and CI-to-CO delay mismatch is limited to ≤5 ns per stage, enabling reliable operation across chains of up to 250 A6280EA-T devices without external repeaters.

Can the A6280EA-T drive LEDs with different forward voltages on each channel?

Yes, the A6280EA-T can drive LEDs with different forward voltages on OUT0, OUT1, and OUT2 because each output operates as an independent constant-current sink with its own voltage compliance range (1–3 V). As long as the LED string voltage remains within that range-and the VIN supply exceeds the highest LED V_F plus headroom-the A6280EA-T maintains regulated current per channel. Exceeding 3 V risks excessive power dissipation in the output transistor.

What happens to the A6280EA-T's output state during thermal shutdown?

During thermal shutdown, the A6280EA-T disables all three output drivers (OUT0/OUT1/OUT2) when junction temperature reaches ~165°C, but retains all latched PWM and dot correction data. The shift register continues accepting new data, and logic inputs (CI, LI, OEI, SDI) remain functional. Outputs resume automatically once junction temperature falls below ~150°C (15°C hysteresis). No reset or reinitialization is required-the A6280EA-T resumes operation with prior brightness and scaling settings intact.

Is the A6280EA-T compatible with 3.3 V microcontrollers?

Yes, the A6280EA-T is compatible with 3.3 V microcontrollers: its logic inputs (CI, LI, OEI, SDI) accept VIH ≥ 2.0 V and VIL ≤ 0.8 V, meeting standard 3.3 V CMOS thresholds. Its logic outputs (CO, LO, OEO, SDO) drive to VOH ≥ 3.8 V and VOL ≤ 0.4 V at ±2 mA, ensuring noise margin when interfacing with 3.3 V receivers. No level-shifting is required-direct connection to 3.3 V GPIO is supported and verified in Allegro's application diagrams.