Allegro MicroSystems A4984SETTR-T

Overview

A4984SETTR-T from Allegro MicroSystems is a DMOS bipolar stepper motor driver IC with integrated translator, supporting full-, half-, quarter-, and eighth-step modes. It delivers ±2 A output current at up to 35 V supply, features automatic mixed/slow decay mode selection, synchronous rectification, and thermal shutdown. It is used in precision motion control systems such as 3D printer extruder/carriage drivers and CNC micro-positioning stages.

For engineers reviewing the A4984SETTR-T datasheet, A4984SETTR-T pinout, A4984SETTR-T application, or A4984SETTR-T equivalent, key selection considerations include its fixed off-time PWM current regulation (30 µs typ.), no-smoke-no-fire (NSNF) compliance in ET package, 32-pin QFN thermal pad layout, and translator-based step command interface requiring only STEP/DIR/MSx logic inputs.

Technical Context

The A4984SETTR-T implements a dual full-bridge DMOS output stage with fixed off-time current regulation per phase, where trip level is set by VREF and external sense resistors (RS1/RS2) via ITripMAX = VREF/(8 × RS). Decay mode-Slow or Mixed-is automatically selected per step transition based on DAC output direction, reducing current waveform distortion from motor back-EMF.

Its integrated translator eliminates need for external phase sequencing logic: a single rising edge on STEP advances one microstep, with resolution controlled by MS1/MS2 logic levels. Protection includes short-to-ground latching, shorted-load repetitive off-time cycling, UVLO (2.8 V typ.), and thermal shutdown (165 °C with 15 °C hysteresis).

Key Specifications

Pinout & Package

32-contact QFN package (5 mm × 5 mm × 0.90 mm) with exposed thermal pad; RoHS-compliant, 100% matte tin leadframe; designed for NSNF (No Smoke No Fire) compliance via isolation of critical pins (OUT1A/OUT1B/SENSE1/VBB1 etc.) using no-connect pins.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TMC2209-LA and DRV8825PWPR, the A4984SETTR-T uniquely combines translator-based simplicity, NSNF-compliant hardware safety, and automatic decay adaptation - making it optimal for embedded motion systems where MCU resources are constrained and safety certification is mandatory.

Availability

A4984SETTR-T is available at Aetrix Electronics and suitable for 3D printer motion control, CNC axis driving, and automated laboratory instrumentation requiring stable component supply, long-term lifecycle support, and certified safety compliance.

Supply support for A4984SETTR-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 sensing and power IC solutions, founded in 1985 and headquartered in Manchester, NH.

The A4984 product line targets cost-sensitive yet safety-aware motion control applications, delivering integrated stepper drivers with built-in translators, robust protection, and NSNF-compliant packaging for medical, industrial, and consumer automation.

FAQ

What is the package type and thermal pad configuration of the A4984SETTR-T?

The A4984SETTR-T uses a 32-pin QFN package measuring 5 mm × 5 mm × 0.90 mm with an exposed thermal pad on the underside. This pad must be soldered directly to a PCB ground plane with thermal vias for effective heat dissipation, achieving 32 °C/W junction-to-ambient thermal resistance on a JEDEC-standard 4-layer board.

How does the A4984SETTR-T implement automatic current decay mode selection?

The A4984SETTR-T monitors DAC output transitions between microsteps: if the new DAC level is lower than the previous, it selects Mixed decay (fast decay for 31.25% of t_OFF, then slow); if equal or higher, it uses Slow decay. This adapts to motor back-EMF in real time, minimizing current distortion and step loss without external control.

Does the A4984SETTR-T support both 3.3 V and 5 V logic interfaces?

Yes, the A4984SETTR-T accepts logic supply (VDD) from 3.0 V to 5.5 V and has 3.3 V/5 V compatible inputs (STEP, DIR, MS1, MS2, ENABLE, SLEEP, RESET) with input thresholds defined as VDD × 0.3 (low) and VDD × 0.7 (high), plus 11% hysteresis - eliminating need for level shifters in mixed-voltage systems.

What protection features are included in the A4984SETTR-T and how do they behave during faults?

The A4984SETTR-T includes short-to-ground (latched disable until SLEEP or power cycle), shorted-load (repetitive off-time cycling), thermal shutdown (165 °C, 15 °C hysteresis), UVLO (2.8 V), and crossover-current protection. All operate autonomously without MCU intervention, preserving system integrity during overloads or wiring errors.

Can the A4984SETTR-T operate in eighth-step mode and what pins control resolution?

Yes, the A4984SETTR-T supports eighth-step microstepping when MS1 and MS2 are both driven high. Resolution is selected solely by MS1/MS2 logic levels per the truth table - full (L/L), half (H/L), quarter (L/H), eighth (H/H) - and takes effect at the next STEP rising edge without requiring reset or reconfiguration.