Allegro MicroSystems A3983SLP-T

Overview

A3983SLP-T from Allegro MicroSystems is a DMOS bipolar stepper motor driver IC with integrated translator, supporting full-, half-, quarter-, and eighth-step microstepping modes. It delivers ±2 A output current at up to 35 V supply, features automatic mixed/slow decay selection, synchronous rectification, and operates with 3.0–5.5 V logic supply. It is used in precision motion control systems such as industrial automation actuators and medical lab equipment positioning stages.

For engineers reviewing the A3983SLP-T datasheet, A3983SLP-T pinout, A3983SLP-T application, or A3983SLP-T equivalent, key selection considerations include its fixed off-time PWM current regulation (20–40 μs), thermal shutdown at 165°C, R_DS(ON) of 0.30–0.45 Ω, 24-pin TSSOP-LP package with exposed thermal pad, and translator-based step sequencing requiring only STEP/DIR inputs.

Technical Context

The A3983SLP-T implements dual full-bridge DMOS output stages with independent current regulation per phase, using external sense resistors (RS1/RS2) and a DAC-controlled trip threshold derived from VREF. Its translator interprets STEP/DIR/MS1/MS2 inputs to generate precise winding current profiles matching microstep resolution tables.

Current decay mode is dynamically selected per step transition: slow decay for increasing current, mixed decay (31.25% fast + remainder slow) for decreasing current - reducing audible noise and improving step accuracy. Synchronous rectification replaces body-diode conduction during decay, lowering power dissipation without external Schottky diodes.

Key Specifications

Pinout & Package

Package: 24-pin TSSOP with exposed thermal pad (LP suffix), 1.2 mm max height, lead-free with matte tin plating. Thermal pad must be soldered to PCB ground plane with thermal vias for reliable operation at rated current.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TB6600HG and DRV8825, the A3983SLP-T uniquely balances translator simplicity, ±2 A capability, and synchronous rectification in a thermally optimized LP package - making it optimal for space-constrained, noise-sensitive motion systems needing plug-and-play microstepping.

Availability

A3983SLP-T is available at Aetrix Electronics and suitable for industrial CNC positioning, medical imaging stage control, automated laboratory pipetting, printed circuit board assembly, and precision motion control systems requiring stable component supply and long-term lifecycle support.

Supply support for A3983SLP-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 semiconductor company specializing in high-performance magnetic sensing and power ICs for motion control, automotive, and industrial applications.

The A3983 product line delivers fully integrated stepper drivers with on-chip translators, targeting applications where minimal MCU overhead and deterministic microstepping performance are essential - especially in resource-constrained embedded motion systems.

FAQ

What is the maximum motor supply voltage supported by the A3983SLP-T?

The A3983SLP-T supports a motor supply voltage (VBB) range of 8 V to 35 V. Absolute maximum rating is 35 V - exceeding this may cause permanent damage. Operation below 8 V is not guaranteed due to internal charge pump and regulator requirements. The A3983SLP-T maintains stable current regulation across this range when paired with appropriate sense resistors and thermal management.

How does the A3983SLP-T determine current decay mode during microstepping?

The A3983SLP-T automatically selects decay mode per step: slow decay when the next DAC output level is equal to or higher than the previous level (indicating rising current), and mixed decay (31.25% fast + remainder slow) when the DAC output decreases (indicating falling current). This behavior is implemented in hardware and requires no software configuration - a core feature of the A3983SLP-T's translator architecture.

Can the A3983SLP-T operate without external sense resistors?

No, the A3983SLP-T requires external sense resistors (RS1 and RS2) connected between SENSE1/SENSE2 pins and ground. These resistors set the current trip threshold via I_TripMAX = VREF / (8 × RS). Omitting them disables current regulation and risks device failure due to uncontrolled motor current. The A3983SLP-T datasheet specifies a maximum 0.5 V sense voltage - limiting RS to ≥0.25 Ω at ±2 A.

What is the purpose of the exposed thermal pad on the A3983SLP-T package?

The exposed thermal pad on the A3983SLP-T provides a low-thermal-resistance path from the die to the PCB ground plane. When soldered directly to a copper area with thermal vias, it enables R_θJA = 28°C/W - essential for sustaining ±2 A output current without exceeding the 150°C maximum junction temperature. Leaving the pad unconnected or floating violates thermal design requirements and risks premature thermal shutdown or failure.

Does the A3983SLP-T support sixteenth-step microstepping?

No, the A3983SLP-T supports full-, half-, quarter-, and eighth-step microstepping only, as defined by the MS1/MS2 truth table. Although some documentation sections mention "sixteenth-step", the official Electrical Characteristics and Functional Description sections - including Table 1 and Figure 5 - confirm eighth-step as the finest resolution. The A3983SLP-T does not implement 16× microstepping; that capability belongs to later-generation Allegro devices like the A4988 or MP6500.