Allegro MicroSystems A6276SLW

Overview

A6276SLW from Allegro MicroSystems is a 16-bit serial-input, constant-current latched LED driver in 24-pin SOICW package, featuring 16 NPN sink outputs with user-adjustable current (up to 90 mA per channel via R_EXT), 20 MHz serial data rate at 5 V logic supply, and active-low OUTPUT ENABLE for inter-digit blanking. It serves as the core driver IC in multiplexed LED display modules requiring precise current regulation and microprocessor interface.

For engineers reviewing the A6276SLW datasheet, A6276SLW pinout, A6276SLW application, or A6276SLW equivalent, key selection criteria include its –20°C to +85°C ambient rating, SOICW thermal resistance (R_θJA = 85°C/W), undervoltage lockout (3.4–4.0 V), and compatibility with cascaded LED column drivers in industrial signage and instrumentation displays.

Technical Context

The A6276SLW integrates a 16-bit CMOS shift register, parallel latches, and 16 matched NPN constant-current sink drivers on a single BiCMOS die. Its serial-to-parallel conversion is triggered by LATCH ENABLE high, while OUTPUT ENABLE (active low) globally blanks all outputs without affecting latch state.

Current regulation is set externally via R_EXT at Pin 23, enabling precise per-channel sink current from 34.1 mA (REXT = 470 Ω) to 86.8 mA (REXT = 250 Ω) at V_CE = 0.7 V. The device supports daisy-chaining via CMOS SERIAL DATA OUT (Pin 22) and exhibits propagation delays ≤1000 ns across CLOCK, LATCH, and ENABLE inputs.

Key Specifications

Pinout & Package

24-pin SOICW (Small Outline Integrated Circuit, Wide-body) package with gull-wing leads, 1.27 mm pitch, and exposed thermal pad not present (unlike LP variant). Dimensions: 15.40 × 7.50 × 2.65 mm (L × W × H).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TB62706BF, A6276SLW adds undervoltage lockout and higher current capability, improving reliability in fluctuating supplies; versus A6275ELWTR-T, it halves component count for 16-bit displays but increases thermal load per package-requiring careful SOICW copper pour design.

Availability

A6276SLW is available at Aetrix Electronics and suitable for industrial panel meters, commercial LED signage, and appliance control panels requiring stable component supply despite its Last Time Buy status.

Supply support for A6276SLW 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, headquartered in Worcester, Massachusetts.

The A6276 product line delivers integrated LED driver solutions optimized for multiplexed alphanumeric and graphic displays in industrial and commercial equipment.

FAQ

What is the maximum allowable output current per channel for A6276SLW?

The A6276SLW supports up to 90 mA constant-current sink per output (Pins 5–20) when configured with R_EXT = 250 Ω and V_CE = 0.7 V. At 85°C ambient, derating applies: continuous 90 mA is achievable only with adequate PCB copper area due to its SOICW R_θJA of 85°C/W. For sustained full-load operation, thermal simulation using PD(act) = DC × (V_CE × I_O × 16) + (V_DD × I_DD) is recommended before finalizing layout.

Does A6276SLW support daisy-chaining with other LED drivers?

Yes, A6276SLW supports daisy-chaining via its CMOS SERIAL DATA OUT (Pin 22), which connects directly to the SERIAL DATA IN of the next A6276SLW or compatible device. This enables scalable LED column expansion without additional MCU GPIOs. The 20 MHz max data rate and 40 ns CLOCK-to-SERIAL DATA OUT delay ensure timing integrity across chains of up to 10+ devices when using proper PCB trace length matching and termination.

What is the purpose of the REXT pin on A6276SLW?

The REXT pin (Pin 23) on A6276SLW connects to an external resistor that sets the constant-current value for all 16 output drivers simultaneously. With R_EXT = 250 Ω, typical output current is 75.5 mA per channel at V_CE = 0.7 V; with R_EXT = 470 Ω, it drops to 40.0 mA. This single-resistor calibration eliminates per-channel trimming, simplifies BOM, and ensures tight current matching (±1.5% typical) across all outputs-critical for uniform LED brightness in displays.

How does the OUTPUT ENABLE function work on A6276SLW?

The OUTPUT ENABLE pin (Pin 21) on A6276SLW is an active-low control that globally disables all 16 output drivers (Pins 5–20) without altering the data stored in the latches. When high, outputs are blanked (OFF); when low, outputs reflect their latched states. This enables hardware-based inter-digit blanking in multiplexed LED displays, eliminating software delays and ensuring precise timing control-especially valuable in high-refresh-rate applications like oscilloscope graticules or real-time status indicators.

Is A6276SLW compatible with 3.3 V microcontrollers?

A6276SLW requires a 4.5–5.5 V logic supply (VDD = 5 V typical) and is not 3.3 V logic-compatible. Its VIH threshold is 0.7×VDD (≥3.5 V), and VIL is ≤0.3×VDD (≤1.5 V), making direct connection to 3.3 V MCU GPIOs unsafe without level translation. A6276SLW must be driven by 5 V-tolerant outputs or paired with a dual-supply level shifter (e.g., TXB0108) to interface reliably with 3.3 V microcontrollers while preserving timing margins and noise immunity.