Allegro MicroSystems A3988SEVTR-1-T

Overview

A3988SEVTR-1-T from Allegro MicroSystems is a quad DMOS full-bridge PWM motor driver in a 36-pin QFN (EV) package, rated for 1.2 A per bridge and 36 V load supply. It supports microstepping (full/half/quarter) of bipolar stepper motors and independent forward/reverse/coast control of up to four DC motors. Its fixed off-time of 8.1 µs, mixed-decay PWM current regulation, and synchronous rectification enable low-noise, high-accuracy motion control in compact industrial actuators.

For engineers reviewing the A3988SEVTR-1-T datasheet, A3988SEVTR-1-T pinout, A3988SEVTR-1-T application, or A3988SEVTR-1-T equivalent, key selection considerations include its discontinued status, 8.1 µs off-time variant, EV-package thermal performance (R_θJA = 27 °C/W), and compatibility with 3.3 V/5 V logic interfaces in multi-motor embedded motion systems.

Technical Context

The A3988SEVTR-1-T implements four independent N-channel DMOS full bridges with fixed off-time PWM current regulation using external sense resistors and per-bridge VREF inputs. Its mixed-decay mode-30.1% fast decay followed by slow decay-reduces audible noise and improves step accuracy while minimizing power dissipation.

Internal synchronous rectification replaces body-diode conduction during current decay, lowering I²R losses. Protection includes thermal shutdown (T_J = 155–175 °C), UVLO on VBB (7.3–7.9 V) and VDD (2.65–2.95 V), and crossover-current prevention via 600 ns dead time between bridge transitions.

Key Specifications

Pinout & Package

Package: 36-pin QFN (EV), 6 mm × 6 mm, 0.90 mm nominal height, with exposed thermal pad for PCB-level heat sinking.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad full-bridge motor driver applications.

Compared with A3988SEVTR-1-T, A5988GEVTR-1-T offers superior thermal margin and tighter current regulation for demanding motion profiles, while A3988SEVTR-T provides identical footprint but reduced microstepping fidelity due to longer off-time-making it viable only for cost-sensitive, low-speed replacements.

Availability

A3988SEVTR-1-T is available at Aetrix Electronics and suitable for industrial automation retrofitting, medical device servicing, and lab equipment maintenance requiring stable component supply despite end-of-life status.

Supply support for A3988SEVTR-1-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 of high-performance magnetic sensors and power ICs, specializing in motion control, energy-efficient power conversion, and precision current sensing.

The A3988 product line delivers integrated DMOS motor drivers optimized for compact, thermally constrained stepper and DC motor applications in industrial, medical, and instrumentation systems.

FAQ

Is A3988SEVTR-1-T still in production?

No, A3988SEVTR-1-T was discontinued effective September 30, 2024. Allegro no longer manufactures or supplies this part. Aetrix Electronics holds remaining authorized inventory for legacy support, but new designs should migrate to A5988GEVTR-1-T. The A3988SEVTR-1-T datasheet remains valid for existing implementations, and thermal/mechanical design data applies unchanged to its successor.

What is the key functional difference between A3988SEVTR-1-T and A3988SEVTR-T?

The A3988SEVTR-1-T uses an 8.1 µs fixed off-time PWM cycle, enabling higher step rates and finer current resolution than the A3988SEVTR-T's 30 µs off-time. This results in improved microstepping smoothness and reduced motor heating at speed. Both share identical pinout, package, and feature set-but A3988SEVTR-1-T's shorter off-time directly enhances dynamic performance in precision motion applications.

Can A3988SEVTR-1-T drive stepper motors in quarter-step mode?

Yes, A3988SEVTR-1-T supports full, half, and quarter-step operation via its 2-bit I0x/I1x control interface per bridge and per-phase VREF inputs. Quarter-step sequencing achieves 400 steps/rev on a standard 200-step motor, with current amplitudes set to 100%, 71%, 0%, −71%, and −100% of I_TRIP. The 8.1 µs off-time ensures stable regulation at these intermediate levels without current overshoot.

What thermal design is required for A3988SEVTR-1-T at 1.2 A per bridge?

A3988SEVTR-1-T requires soldering its exposed thermal pad to a minimum 250 mm² copper area on an inner ground plane, connected via ≥6 thermal vias (0.3 mm diameter). With R_θJA = 27 °C/W, sustained 1.2 A per bridge at 32 V demands ambient ≤55 °C or forced airflow. Derating curves show 1.2 A is sustainable only below 75 °C ambient on a 4-layer JEDEC board-exceeding this risks thermal shutdown.

Does A3988SEVTR-1-T support 3.3 V logic interfaces?

Yes, A3988SEVTR-1-T accepts 3.0–5.5 V on VDD, making it fully compatible with 3.3 V microcontrollers without level shifters. Logic inputs (PHASEx, I0x, I1x) have 0.3×VDD low threshold and 0.7×VDD high threshold, with 150–500 mV hysteresis for noise immunity. Input current stays below ±1 µA, minimizing MCU GPIO loading-critical for battery-powered A3988SEVTR-1-T deployments.