Allegro MicroSystems A6276ELPTR-T

Overview

A6276ELPTR-T from Allegro MicroSystems is a 16-bit serial-input, constant-current latched LED driver in 24-pin TSSOP with exposed thermal pad. It integrates a BiCMOS shift register, data latches, and 16 NPN sink drivers, supporting up to 90 mA per output with user-defined current via R_EXT, 20 MHz serial data rate at 5 V, and inter-digit blanking via active-low ENABLE. It is used in multiplexed LED displays requiring precise current control and cascaded drive expansion.

For engineers reviewing the A6276ELPTR-T datasheet, A6276ELPTR-T pinout, A6276ELPTR-T application, or A6276ELPTR-T equivalent, key selection criteria include its 24-pin TSSOP-LP package with thermal pad, –40°C to +85°C ambient rating, undervoltage lockout at ~3.7 V, 16-channel constant-current sinking capability, and CMOS serial data output for daisy-chaining.

Technical Context

The A6276ELPTR-T implements a two-stage serial-to-parallel architecture: a 16-bit CMOS shift register accepts data on the rising edge of CLOCK, then transfers contents to parallel latches upon high-level LATCH ENABLE. Output drivers remain latched and stable regardless of subsequent serial shifts or LATCH ENABLE state.

All 16 outputs are NPN current sinks with matched performance (±1.5% typical current matching), controlled by a single external resistor (REXT) connected to pin 23. The OUTPUT ENABLE input (pin 21) is active-low and disables all drivers simultaneously without affecting latch contents, enabling synchronized blanking across digits or segments.

Key Specifications

Pinout & Package

Package: 24-pin TSSOP with exposed thermal pad (LP suffix), RoHS-compliant, 100% matte tin leadframe plating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TB62706BF, A6276ELPTR-T delivers 50% higher current headroom and guaranteed low-temperature operation; compared with A6275ELWTR-T, it halves component count and interconnects for 16-channel systems while leveraging superior thermal performance of the LP package.

Availability

A6276ELPTR-T is available at Aetrix Electronics and suitable for LED signage, industrial HMI displays, and embedded annunciator systems requiring stable component supply and long-term manufacturability.

Supply support for A6276ELPTR-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 and manufacturer of high-performance magnetic sensors, motor drivers, and precision power ICs, headquartered in Worcester, Massachusetts.

The A6276 product line was developed specifically for high-reliability, constant-current LED display driving in industrial and commercial applications, emphasizing thermal robustness, latch stability, and seamless microcontroller interfacing.

FAQ

What is the maximum continuous output current per channel for A6276ELPTR-T at 85°C ambient?

The A6276ELPTR-T supports up to 90 mA per output continuously at T_A = 85°C when mounted on a 2-layer PCB with 3.8 in² copper area per side (R_θJA = 32°C/W). This rating assumes V_CE ≤ 0.75 V and proper thermal pad soldering. At higher V_CE or reduced copper area, derating is required per the thermal curves in the datasheet. The A6276ELPTR-T achieves this via its exposed thermal pad and optimized TSSOP-LP package construction.

How does the R_EXT resistor set output current in A6276ELPTR-T?

In the A6276ELPTR-T, the external resistor connected between pin 23 (REXT) and ground establishes a reference voltage that controls all 16 output current sources. For example, with R_EXT = 250 Ω, typical output current is 75.5 mA per channel at V_CE = 0.7 V. The relationship is inverse and linear: lower R_EXT yields higher current. The A6276ELPTR-T guarantees ±1.5% matching between any two outputs under identical conditions.

Can A6276ELPTR-T be cascaded with other A6276 devices, and how is it implemented?

Yes, the A6276ELPTR-T supports daisy-chaining via its CMOS SERIAL DATA OUT (pin 22), which outputs the shifted-out bit from the internal 16-bit register. To cascade, connect pin 22 of one A6276ELPTR-T to pin 2 (SERIAL DATA IN) of the next. All devices share common CLOCK, LATCH ENABLE, and OUTPUT ENABLE lines. This allows building 32-, 48-, or N×16-channel LED drivers using only three MCU control signals - a key advantage of the A6276ELPTR-T architecture.

What is the purpose and behavior of the OUTPUT ENABLE (OE) pin on A6276ELPTR-T?

The OUTPUT ENABLE (pin 21) on the A6276ELPTR-T is an active-low global control that disables all 16 output drivers simultaneously without altering the data stored in the internal latches. When OE is high, outputs are turned off (blanked); when low, outputs reflect their latched states. This enables precise inter-digit blanking in multiplexed displays and eliminates ghosting. The A6276ELPTR-T specifies a minimum OE pulse width of 4.5 μs for reliable blanking.

Does A6276ELPTR-T include undervoltage lockout, and what is its threshold?

Yes, the A6276ELPTR-T incorporates an undervoltage lockout (UVLO) circuit that disables internal logic and outputs when V_DD falls below approximately 3.7 V (typical), with a range of 3.4 V to 4.0 V. This prevents erratic behavior during power-up, brown-out, or noisy supply conditions. Once V_DD rises above the UVLO threshold, the A6276ELPTR-T resumes normal operation without requiring reset - critical for robust LED display operation in industrial environments.