Allegro MicroSystems A2982ELW

Overview

A2982ELW from Allegro MicroSystems is an 8-channel high-side source driver IC designed for interfacing 5 V logic (TTL, CMOS, DTL) with inductive or resistive loads up to 50 V and –500 mA per channel. It integrates input current-limiting resistors and output clamp diodes, features active-high inputs, and operates from 5 V to 50 V supply voltage. Commonly used to drive relays, solenoids, stepper motors, and LEDs in industrial control systems.

For engineers reviewing the A2982ELW datasheet, A2982ELW pinout, A2982ELW application, or A2982ELW equivalent, key selection criteria include its 20-pin SOICW package, 50 V output breakdown rating, –500 mA source current capability, integrated transient suppression, and compatibility with 5 V logic families without external components.

Technical Context

The A2982ELW implements eight independent NPN Darlington source drivers with built-in base resistors and output flyback diodes. Each channel supports active-high logic-level control and delivers up to –500 mA output current while sustaining 50 V collector-emitter voltage.

It operates across –20 °C to +85 °C ambient temperature, with a maximum junction temperature of 150 °C and thermal resistance θ_JA = 90 °C/W. The device requires no external pull-down resistors on unused inputs but recommends ~10 kΩ pull-downs if inputs may float during power-up.

Key Specifications

Pinout & Package

The A2982ELW is housed in a 20-pin wide-body SOIC (SOICW) package with 100% matte-tin leadframe plating and Pb-free construction. Pin 1 is marked by a terminal #1 indicator; pins 10 and 11 are NC (no connect), distinguishing it from discontinued 18-pin variants while maintaining electrical pin compatibility for pins 1–9 and 12–20.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-side source driver applications.

Compared with ULN2803A and TB6549FG, the A2982ELW uniquely provides true high-side sourcing with separate logic/load grounds and no added complexity-ideal for isolated 24 V relay banks where simplicity, reliability, and minimal external components are critical.

Availability

A2982ELW is available at Aetrix Electronics and suitable for industrial relay control, electromechanical printer interfaces, LED array driving, and stepper motor phase control requiring stable component supply and long-term manufacturability.

Supply support for A2982ELW 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, power ICs, and precision motion-control solutions headquartered in Worcester, Massachusetts.

The A2982ELW belongs to Allegro's legacy high-side driver product line, engineered specifically for robust, low-component-count interfacing between microcontrollers and industrial inductive loads.

FAQ

What is the maximum load supply voltage supported by the A2982ELW?

The A2982ELW supports a maximum load supply voltage (V_S) of 50 V, as specified in its Absolute Maximum Ratings. This allows direct use with common industrial 24 V and 48 V DC systems. Operation below 5 V is not guaranteed; minimum recommended V_S is 5 V per datasheet specifications. The A2982ELW maintains rated performance across this full 5–50 V range without derating.

Does the A2982ELW require external flyback diodes when driving relays?

No, the A2982ELW does not require external flyback diodes when driving relays or other inductive loads. Each output includes an integrated clamp diode rated for up to 50 μA reverse leakage and capable of dissipating energy from typical relay coils. This eliminates external components and reduces PCB footprint. The A2982ELW's internal diodes are optimized for standard 24 V relay applications with coil energies within its specified safe operating area.

Can the A2982ELW be used with 3.3 V logic inputs?

The A2982ELW is specified for 5 V logic compatibility (TTL, CMOS, DTL) and has a minimum input high threshold of 2.0 V. While some units may function with 3.3 V logic, the datasheet does not guarantee operation below 2.4 V input high voltage, and input current rises significantly above 2.4 V. For reliable 3.3 V system integration, level-shifting or buffer circuitry is recommended. The A2982ELW is not characterized for 3.3 V-only operation.

What is the thermal performance of the A2982ELW in its SOICW package?

The A2982ELW in the 20-pin SOICW package has a junction-to-ambient thermal resistance (θ_JA) of 90 °C/W under standard JEDEC test conditions. At 25 °C ambient and full 500 mA per channel (eight channels active), total power dissipation reaches ~1.44 W, resulting in ~130 °C junction rise - exceeding the 150 °C absolute maximum. Derating is required: only 3–4 channels should operate continuously at full load. The A2982ELW's thermal design assumes natural convection and proper copper pour on the GND pad.

How does the A2982ELW handle unused input pins?

All unused inputs on the A2982ELW must be connected to ground. The datasheet explicitly states that floating inputs are not allowed during power application. If inputs must remain inactive but cannot be hard-wired low, a ~10 kΩ pull-down resistor is recommended per input to ensure stable logic-low state and prevent unintended channel activation. Leaving inputs unconnected risks erratic output behavior and increased quiescent current in the A2982ELW.