Allegro MicroSystems A6275SLW

Overview

A6275SLW from Allegro MicroSystems is an 8-bit serial-input constant-current latched LED driver with eight NPN sink outputs, 90 mA per channel capability, undervoltage lockout (UVLO), and CMOS-compatible 20 MHz serial data input-designed for multiplexed LED displays in industrial signage and instrumentation panels.

For engineers reviewing the A6275SLW datasheet, A6275SLW pinout, A6275SLW application, or A6275SLW equivalent, this device supports cascadeable serial daisy-chaining, inter-digit blanking via active-low OUTPUT ENABLE, and user-adjustable current setting via external R_EXT, making it critical for high-reliability LED matrix control where thermal management and logic-level compatibility are essential.

Technical Context

The A6275SLW integrates a CMOS shift register, parallel latches, and eight bipolar NPN constant-current sink drivers on a single BiCMOS die. Its architecture enables synchronous serial-to-parallel conversion with latch strobing on LATCH ENABLE high, and output enable/disable via open-drain–compatible OUTPUT ENABLE (active low).

It features undervoltage lockout triggering at 3.4–4.0 V, supports 5 V logic supply with typical 20 MHz clock rate, and uses a single external resistor (R_EXT) to set all eight output currents-ensuring matched ±6.0% current matching across outputs at V_CE = 0.7 V and R_EXT = 250 Ω.

Key Specifications

Pinout & Package

16-pin SOICW (LW) package with exposed thermal pad (not electrically connected); JEDEC MS-013 AA compliant; 100% matte tin leadframe plating; RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with A6275SLW, the A6279 offers diagnostic enhancements and better thermal efficiency for new designs, while TB62705CP provides basic functionality at lower cost but requires supplemental circuitry for robust industrial operation - neither is a direct drop-in substitute without validation.

Availability

A6275SLW is available at Aetrix Electronics and suitable for industrial LED signage, instrumentation panel displays, and point-of-sale terminals requiring stable component supply despite its Last Time Buy status.

Supply support for A6275SLW 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 and manufacturer of high-performance magnetic sensors, motor drivers, and power ICs, founded in 1989 and headquartered in Worcester, Massachusetts.

The A6275 product line was developed specifically for LED display systems requiring integrated constant-current sinking, serial expandability, and thermal resilience in industrial environments - targeting applications where reliability and pin-level compatibility outweigh feature bloat.

FAQ

What is the maximum continuous output current per channel for the A6275SLW?

The A6275SLW supports up to 90 mA per output channel continuously across the full operating ambient temperature range of –20°C to +85°C when mounted on a 4-layer PCB per JEDEC standards. This rating assumes proper thermal design and use of the SOICW package's specified R_θJA of 48 °C/W. The actual current is set by the external R_EXT resistor and verified at V_CE = 0.7 V in the datasheet's electrical characteristics table.

Does the A6275SLW include undervoltage lockout, and what is its threshold?

Yes, the A6275SLW includes built-in undervoltage lockout (UVLO) that disables output drivers until the VDD supply reaches a valid level. The UVLO threshold is specified as 3.4 V minimum to 4.0 V maximum, ensuring stable operation during power-up sequences. This feature prevents erratic LED behavior or partial activation during brown-out conditions - a key reliability factor confirmed in the Absolute Maximum Ratings and Electrical Characteristics sections of the A6275SLW datasheet.

Can multiple A6275SLW devices be cascaded, and how is that implemented?

Yes, the A6275SLW supports serial daisy-chaining via its CMOS SERIAL DATA OUT (pin 14), which connects directly to the SERIAL DATA IN (pin 2) of the next device. This enables expansion beyond 8 outputs without additional microcontroller pins. The cascade operation is validated up to 10 MHz clock frequency, and timing parameters such as tpHL and tpLH are specified for CLOCK-to-SERIAL DATA OUT propagation - ensuring deterministic behavior across chains of A6275SLW units.

What is the purpose of the R_EXT pin (pin 15) on the A6275SLW?

The R_EXT pin (pin 15) on the A6275SLW connects to an external resistor that sets the constant-current value for all eight output channels simultaneously. The relationship is inverse: lower resistance yields higher current (e.g., 250 Ω → ~75.5 mA typ), while 470 Ω yields ~40.0 mA typ. This single-point adjustment eliminates per-channel resistor networks, simplifies BOM, and ensures matched current across outputs - a core design feature explicitly documented in the Applications Information and Electrical Characteristics tables for the A6275SLW.

Is the A6275SLW still in production, and what does "Last Time Buy" mean for this part?

The A6275SLW is classified as Last Time Buy (LTB) by Allegro MicroSystems, with the deadline for final orders set at April 30, 2011. This means the device is obsolete and no longer in active production; Aetrix Electronics maintains limited legacy stock for existing customer applications only. New designs should transition to the recommended successor A6279. Samples are unavailable, and long-term supply cannot be guaranteed - users must plan for obsolescence mitigation when specifying the A6275SLW.