Allegro MicroSystems A6279EETTR-T

Overview

A6279EETTR-T from Allegro MicroSystems is a 16-channel serial-input constant-current latched LED driver with open-LED detection, designed for high-reliability LED display systems. It features 3.0–5.5 V logic supply operation, up to 90 mA per output sink current (set via external R_EXT), 20 ns output staggering delay, and CMOS serial data output for cascading. Used in industrial signage and automotive dashboard displays where fault-aware LED driving is critical.

For engineers reviewing the A6279EETTR-T datasheet, A6279EETTR-T pinout, A6279EETTR-T application, or A6279EETTR-T equivalent, key selection criteria include its 28-pin MLP (QFN) package with exposed thermal pad, integrated UVLO and thermal shutdown, Schmitt-trigger inputs for noise immunity, and real-time open-circuit diagnostics via SERIAL DATA OUT.

Technical Context

The A6279EETTR-T integrates a 16-bit BiCMOS shift register, parallel latches, and NPN constant-current sink drivers - all controlled by three digital inputs: CLOCK, LATCH ENABLE, and OUTPUT ENABLE. Its open-LED detection operates in dedicated Test mode, requiring precise OE/LE/CLOCK sequencing to read error bits back via SERIAL DATA OUT.

Internal circuitry includes undervoltage lockout (2.15–2.85 V trip), thermal shutdown at 165°C (15°C hysteresis), and output current matching within ±6% across channels. The device supports up to 25 MHz serial data input rate and exhibits 75–150 ns output rise/fall times under typical load conditions.

Key Specifications

Pinout & Package

Package: 28-pin MLP (QFN), 4.0 × 4.0 mm body, 0.90 mm nominal height, exposed thermal pad (EP) on underside for enhanced heat dissipation. Lead-free, 100% matte tin plating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLC59283DBQR and MAX7219CWG+, the A6279EETTR-T uniquely combines per-channel open-LED diagnostics, programmable current via single R_EXT, and seamless daisy-chain capability - making it optimal for custom LED matrix designs requiring field-serviceability and thermal resilience.

Availability

A6279EETTR-T is available at Aetrix Electronics and suitable for industrial signage, automotive dashboard displays, and medical equipment panels requiring stable component supply and long-lifecycle support.

Supply support for A6279EETTR-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 is a U.S.-based designer of high-performance magnetic sensors and power ICs, specializing in motion control, energy-efficient power conversion, and robust interface solutions.

The A6279 product line delivers serial-input constant-current LED drivers with integrated diagnostics - engineered specifically for mission-critical display systems where reliability, thermal stability, and fault visibility are non-negotiable.

FAQ

What is the function of the REXT pin on the A6279EETTR-T?

The REXT pin on the A6279EETTR-T connects to an external resistor that sets the magnitude of constant current for all 16 output channels. For example, a 470 Ω resistor yields ~40 mA per output at V_CE = 0.7 V. This single-point adjustment eliminates per-channel trimming and ensures matched brightness across LED arrays driven by the A6279EETTR-T.

Does the A6279EETTR-T support daisy-chaining with other A6279 devices?

Yes, the A6279EETTR-T supports daisy-chaining via its SERIAL DATA OUT pin, which feeds directly into the SERIAL DATA IN of the next A6279EETTR-T in the chain. This enables expansion beyond 16 outputs without additional MCU GPIOs - all while preserving open-LED detection capability across the full cascade when operated in Test mode.

How does open-LED detection work on the A6279EETTR-T?

Open-LED detection on the A6279EETTR-T operates in a dedicated Test mode initiated by specific OE/LE/CLOCK sequences. When enabled, each output's V_CE is compared to 0.30 V; values below trigger an error bit (0), readable via SERIAL DATA OUT. This allows the host MCU to identify exactly which LED string has failed - a capability confirmed in the A6279EETTR-T functional description and timing diagrams.

What thermal management is required for the A6279EETTR-T in continuous 90 mA operation?

At full 90 mA per channel (16 channels), the A6279EETTR-T requires PCB-level thermal management: the exposed pad (EP) must be soldered to a solid GND plane with ≥4 thermal vias (0.3 mm diameter, filled or plated) connecting to inner-layer copper. With this layout, the device sustains 85°C ambient at full load - verified by its 32°C/W θ_JA rating for the 28-pin MLP package.

Is the A6279EETTR-T pin-compatible with other A6279 package variants?

Yes, all A6279 variants - including A6279EETTR-T (28-pin MLP), A6279ELPTR-T (24-pin TSSOP), and A6279ELWTR-T2 (24-pin SOIC) - share identical pin functions and electrical behavior. However, pin numbering differs due to package geometry; the A6279EETTR-T uses a 28-pin grid with NC positions, while TSSOP/SOIC use 24-pin layouts - requiring board redesign for substitution.