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Allegro MicroSystems A3982SLB-T
- Part No.:
- A3982SLB-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
A3982SLB-T.pdf
- Description:
- IC MTR DRV BIPOLAR 3-5.5V 24SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,317
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Product details
Overview
A3982SLB-T from Allegro MicroSystems is a DMOS bipolar stepper motor driver IC with integrated translator, designed for full- and half-step excitation of up to ±2 A per phase at 35 V supply, featuring automatic mixed/slow decay mode selection, synchronous rectification, and fixed off-time PWM current regulation. It enables simplified microstepping control in industrial motion systems, 3D printer axes, and CNC positioning stages.
For engineers reviewing the A3982SLB-T datasheet, A3982SLB-T pinout, A3982SLB-T application, or A3982SLB-T equivalent, key selection criteria include its 24-pin SOICW (LB) package with fused PGND leads, 30 μs typical fixed off-time, ±2 A output rating, VREF-based current programming, and translator-driven STEP/DIR interface requiring no external phase sequencing logic.
Technical Context
The A3982SLB-T integrates dual N-channel DMOS full-bridge drivers with independent current-sense comparators, DAC-controlled trip-level modulation, and an on-chip translator that sequences phase currents based on STEP/DIR/MS1 inputs. Its fixed off-time PWM regulator uses ROSC-set timing (23–37 μs) and blanking (0.7–1.3 μs) to suppress false overcurrent detection during switching transients.
Automatic decay mode selection operates per-phase: slow decay when step increases winding current, mixed decay (31.25% fast + remainder slow) when step reduces current-minimizing back-EMF distortion and audible noise. Synchronous rectification replaces body-diode conduction with low-RDS(on) FET paths during decay, reducing power dissipation by >30% versus asynchronous operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | ±2 A per phase - supports NEMA 17–23 stepper motors without external heatsinking under typical PCB thermal conditions |
| Supply Voltage | 8–35 V VBB - compatible with 12 V, 24 V, and 32 V industrial motor rails |
| RDS(on) | 0.33–0.46 Ω - limits conduction loss to <1.8 W per bridge at 2 A, enabling compact layout |
| Fixed Off-Time | 23–37 μs (ROSC = 25 kΩ) - sets minimum PWM period for stable current regulation across temperature |
| VREF Range | 0–4 V - scales full-scale current trip point via ITRIPMAX = VREF/(8 × RS) |
| Logic Supply | 3.0–5.5 V VDD - interoperable with 3.3 V and 5 V microcontrollers without level shifting |
| Thermal Shutdown | 165 °C with 15 °C hysteresis - prevents latch-up during overload or poor heatsinking |
Pinout & Package
Package: 24-pin wide-body SOIC (suffix LB), with internally fused PGND leads (pins 6 & 7, and 18 & 19) for enhanced thermal dissipation and reduced ground impedance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OUT1A, OUT1B, OUT2A, OUT2B | DMOS full-bridge outputs | Drive bipolar stepper windings; each pair forms one phase leg with source/sink capability |
| SENSE1, SENSE2 | Current sense inputs | Connect to low-side sense resistors (RS1/RS2); voltage must not exceed 0.5 V to avoid damage |
| VBB1, VBB2 | Motor supply inputs | Independent high-voltage rails for each bridge; decoupling required near pins |
| PGND (pins 6, 7, 18, 19) | Power ground | Fused internal connection improves current sharing and thermal path to PCB copper |
| STEP, DIR, MS1, ENABLE, RESET | Digital control inputs | 5 V tolerant logic; STEP rising edge advances motor one step; MS1 selects full/half-step mode |
| VDD, REF, VREG, ROSC | Analog/precision nodes | VDD powers logic; REF sets current scale; ROSC sets off-time; VREG requires 0.22 μF ceramic decoupling |
| CP1, CP2, VCP | Charge pump circuit | Generate gate drive voltage > VBB for high-side N-FETs; require 0.1 μF ceramic capacitors |
Key Features
| Feature | Design Value |
|---|---|
| Integrated translator | Eliminates need for external microcontroller-based phase sequencing-single STEP pulse advances motor one step |
| Automatic decay mode selection | Per-phase real-time decision between slow and mixed decay based on current direction change, improving step accuracy and reducing resonance |
| Synchronous rectification | Replaces body diodes with active FET conduction during decay, cutting power loss by ≥35% versus asynchronous operation |
| Fused PGND leads | Pins 6/7 and 18/19 internally joined to lower ground loop inductance and improve thermal transfer to PCB copper |
| Comprehensive protection | Includes UVLO (2.7 V enable threshold), thermal shutdown (165 °C), and crossover-current prevention-no external fault management needed |
Applications
| 3D Printer Motion Control | CNC Milling Axis Driver |
|---|---|
Use Scenario: Precise open-loop positioning of extruder carriage and print bed using NEMA 17 stepper motors. IC Role / Device Role / Timing Role: Translator-driven stepper driver providing full/half-step excitation with automatic current decay adaptation to varying load torque. Use Value: Eliminates microcontroller firmware complexity for step sequencing while maintaining sub-0.1° positional repeatability via synchronized decay control. | Use Scenario: Driving X/Y/Z axis steppers in desktop CNC routers operating at 24 V with peak currents up to 1.8 A. IC Role / Device Role / Timing Role: Bipolar stepper driver with 35 V capability and fused PGND for robust operation under mechanical shock and vibration. Use Value: Fused ground leads reduce ground bounce during rapid direction reversal, preserving step integrity at feed rates >1000 mm/min. |
| Automated Laboratory Stage | Industrial Packaging Conveyor |
Use Scenario: High-accuracy linear stage in optical alignment systems requiring quiet, low-vibration movement. IC Role / Device Role / Timing Role: Stepper driver with mixed decay mode to suppress audible coil whine and minimize current waveform distortion from motor back-EMF. Use Value: Automatic decay selection reduces acoustic noise by >15 dB(A) and improves microstep smoothness at 1/2-step resolution. | Use Scenario: Indexing conveyor belt with intermittent start/stop cycles and frequent direction changes in food processing lines. IC Role / Device Role / Timing Role: Robust stepper driver with thermal shutdown hysteresis (15 °C) and UVLO to withstand brownout events in factory power distribution. Use Value: Self-protecting operation ensures continuous indexing without manual reset after voltage sags or thermal overload. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar stepper motor driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TB6600HG | Higher 4.5 A rating but requires external translator; no integrated step sequencer | Suitable where higher current or custom microstepping is needed, but adds MCU overhead | Select A3982SLB-T when minimizing controller resource usage is critical; choose TB6600HG only if >2 A per phase is required |
| DRV8825 | Lower 2.2 A rating, 3.3 V logic-only interface, no VBB/VDD separation | Better suited for 3.3 V embedded systems but lacks 35 V motor rail support and fused PGND | Prefer A3982SLB-T for industrial 24 V systems needing robust grounding; DRV8825 fits compact 3.3 V designs with lower current needs |
Compared with TB6600HG and DRV8825, the A3982SLB-T uniquely combines translator integration, 35 V motor rail tolerance, fused PGND leads, and automatic decay selection-making it optimal for cost-sensitive, space-constrained industrial motion controllers where firmware simplicity and thermal reliability are prioritized.
Availability
A3982SLB-T is available at Aetrix Electronics and suitable for 3D printer motion control, CNC milling axis drivers, and automated laboratory stage applications requiring stable component supply and long-term industrial availability.
Supply support for A3982SLB-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 sensing and power ICs, headquartered in Worcester, Massachusetts, with global manufacturing and support infrastructure.
The A3982 product line delivers integrated stepper motor drivers with on-chip translators for simplified motion control in industrial automation, medical devices, and precision instrumentation-reducing system-level design effort and firmware burden.
FAQ
What is the maximum motor supply voltage supported by the A3982SLB-T?
The A3982SLB-T supports a maximum motor supply voltage (VBB) of 35 V, as specified in its Absolute Maximum Ratings table. This allows direct interfacing with common industrial 24 V and 32 V DC power rails without external voltage regulation. Operation above 35 V risks permanent damage to the DMOS output stages, and the device includes undervoltage lockout (UVLO) to prevent malfunction below 2.7 V on VDD. The A3982SLB-T maintains full ±2 A output capability across its 8–35 V operating range.
How does the A3982SLB-T implement automatic current decay mode selection?
The A3982SLB-T determines decay mode per phase by comparing the DAC output level before and after each STEP input: if the new DAC value is lower, Mixed decay (31.25% fast + remainder slow) activates; if equal or higher, Slow decay engages. This real-time decision minimizes current waveform distortion caused by motor back-EMF, improving step accuracy and reducing audible noise. The A3982SLB-T performs this selection autonomously-no external control or configuration is required-and applies it independently to each full-bridge.
What is the purpose of the fused PGND leads in the A3982SLB-T's SOICW package?
The A3982SLB-T's 24-pin SOICW (LB) package fuses PGND leads at pins 6 & 7 and pins 18 & 19 to reduce ground loop inductance and improve thermal conduction from the die to the PCB. This internal fusion lowers impedance in high-current return paths during rapid switching, suppressing ground bounce during direction reversal or high-frequency stepping. It also enhances heat dissipation-critical for sustaining ±2 A output in compact industrial layouts-without requiring external ground plane stitching or multiple vias.
Can the A3982SLB-T operate with a 3.3 V logic supply?
Yes, the A3982SLB-T accepts a logic supply (VDD) from 3.0 V to 5.5 V, making it fully compatible with 3.3 V microcontrollers. Input thresholds are referenced to VDD (VIN(1) = 0.7×VDD, VIN(0) = 0.3×VDD), and input hysteresis (150–500 mV) ensures noise immunity. All digital inputs-STEP, DIR, MS1, ENABLE, and RESET-are 5 V tolerant, so no level-shifting is needed when interfacing with mixed-voltage systems. The A3982SLB-T maintains full functionality, including translator operation and current regulation, across this entire VDD range.
What external components are mandatory for stable operation of the A3982SLB-T?
Mandatory external components for the A3982SLB-T include: (1) 0.22 μF ceramic capacitor from VREG to PGND; (2) 0.1 μF ceramic capacitor between CP1 and CP2; (3) 0.1 μF ceramic capacitor between VCP and VBB; (4) current-sense resistors (RS1, RS2) sized per ITRIPMAX = VREF/(8 × RS); and (5) ROSC resistor (e.g., 25 kΩ) from ROSC to PGND. Omitting any of these compromises regulation stability, charge pump operation, or thermal protection-directly impacting A3982SLB-T reliability and output accuracy.
A3982SLB-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Motor Type - Stepper:
- Bipolar
- Motor Type - AC, DC:
- -
- Function:
- Driver - Fully Integrated, Control and Power Stage
- Output Configuration:
- Half Bridge (4)
- Interface:
- Logic
- Technology:
- DMOS
- Step Resolution:
- 1, 1/2
- Applications:
- General Purpose
- Current - Output:
- 2A
- Voltage - Supply:
- 3V ~ 5.5V
- Voltage - Load:
- 8V ~ 35V
- Operating Temperature:
- -20°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SOIC
A3982SLB-T FAQ
1.How can I place an order for A3982SLB-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A3982SLB-T on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for A3982SLB-T reliable?
The price and inventory of A3982SLB-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3982SLB-T is usually 5 days.
3.What payment methods are accepted for A3982SLB-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3982SLB-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3982SLB-T?
A3982SLB-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3982SLB-T order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for A3982SLB-T?
For technical support, including A3982SLB-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3982SLB-T requirements.
6.How does Aetrix verify that A3982SLB-T is sourced from the original manufacturer or authorized distributors?
All A3982SLB-T products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that A3982SLB-T meets industry standards.
7.What is the process for return or replacement of A3982SLB-T?
All A3982SLB-T units undergo pre-shipment inspection (PSI). If there is an issue with A3982SLB-T, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The A3982SLB-T part is unused and in its original packaging.
Return procedure for A3982SLB-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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