Allegro MicroSystems A3983SLPTR

Overview

The A3983SLPTR 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 from 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 A3983SLPTR datasheet, A3983SLPTR pinout, A3983SLPTR application, or A3983SLPTR equivalent, key selection criteria include its fixed off-time PWM current regulation (20–40 μs), thermal shutdown at 165°C, R_DS(ON) ≤ 0.45 Ω (source), 0.37 Ω (sink), and 24-pin TSSOP-LP package with exposed thermal pad for high-power dissipation management.

Technical Context

The A3983SLPTR implements dual full-bridge DMOS output stages with independent current regulation per phase, each controlled by a DAC-driven fixed off-time PWM circuit. Current trip level is set via external sense resistors (RS1/RS2) and VREF, with ITripMAX = VREF / (8 × RS).

Its translator logic interprets STEP/DIR/MS1/MS2 inputs to sequence microsteps without external phase tables; decay mode (Slow or Mixed) is selected automatically per step based on DAC output direction, with Mixed decay applying fast decay for 31.25% of t_OFF, then slow decay for remainder.

Key Specifications

Pinout & Package

Package: 24-pin TSSOP with exposed thermal pad (LP suffix), 7.80 × 4.40 mm body, 1.2 mm max height, lead-free with matte tin plating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TB6600HG and DRV8825, the A3983SLPTR uniquely balances translator simplicity, ±2 A capability, and LP-package thermal performance-making it optimal for mid-power industrial motion systems where firmware overhead and thermal reliability are both critical.

Availability

A3983SLPTR is available at Aetrix Electronics and suitable for industrial CNC positioning, medical infusion pump actuation, automated test equipment (ATE), and 3D printer extruder & axis control requiring stable component supply and long-term production continuity.

Supply support for A3983SLPTR 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 1989 and headquartered in Worcester, Massachusetts.

The A3983 belongs to Allegro's DMOS stepper driver product line, engineered specifically for cost-sensitive, high-reliability motion control applications requiring integrated translation, robust thermal design, and comprehensive fault protection.

FAQ

What is the maximum motor supply voltage supported by the A3983SLPTR?

The A3983SLPTR supports a load supply voltage (VBB) range of 8 V to 35 V under normal operation, with absolute maximum rating at 35 V. During Sleep mode, VBB may remain up to 35 V without damage. Exceeding 35 V risks permanent device failure due to internal DMOS breakdown, and the UVLO circuit disables outputs if VDD falls below 2.7 V during startup.

How does the A3983SLPTR implement automatic current decay mode selection?

The A3983SLPTR monitors DAC output transitions at each STEP edge: 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 selects Slow decay. This behavior is intrinsic to the A3983SLPTR's internal control logic and requires no external configuration-enabling smoother current waveforms and reduced motor noise without software intervention.

Can the A3983SLPTR drive unipolar stepper motors?

No, the A3983SLPTR is designed exclusively for bipolar stepper motors using dual full-bridge topology (OUT1A/OUT1B and OUT2A/OUT2B). It cannot configure its outputs for unipolar 5- or 6-wire motor wiring. Attempting to do so will result in incorrect phase energization and potential loss of torque or overheating. For unipolar applications, a dedicated unipolar driver or external H-bridge reconfiguration is required.

What is the purpose of the exposed thermal pad on the A3983SLPTR package?

The exposed thermal pad on the A3983SLPTR's 24-pin TSSOP-LP package serves as the primary thermal and electrical ground path. It must be soldered directly to a large PCB copper area with thermal vias to achieve the specified R_θJA = 28°C/W. Leaving it unconnected degrades thermal performance by >40%, risking thermal shutdown at currents above 1.2 A and violating the device's safe operating area.

Does the A3983SLPTR require external Schottky diodes for flyback protection?

No-the A3983SLPTR integrates synchronous rectification that actively turns on low-R_DS(ON) DMOS FETs during current decay, effectively replacing body diode conduction. This eliminates the need for external Schottky diodes in most applications and reduces power dissipation significantly. External diodes are unnecessary unless operating outside the specified VBB range or under extreme transient conditions not covered by internal protection.