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Allegro MicroSystems A3989SEVTR-T
- Part No.:
- A3989SEVTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 36-VFQFN Exposed Pad
- Datasheet:
-
A3989SEVTR-T.pdf
- Description:
- IC MTR DRVR BIPOLAR 3-5.5V 36QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,065
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Product details
Overview
A3989SEVTR-T from Allegro MicroSystems is a discontinued bipolar stepper and high-current DC motor driver IC designed for dual-motor control in embedded motion systems. It supports up to 1.2 A per phase for bipolar stepper motors and up to 2.4 A continuous for DC motors, operates from 8–36 V supply, and integrates fixed off-time PWM current regulation with mixed-decay mode for reduced audible noise and improved step accuracy.
For engineers reviewing the A3989SEVTR-T datasheet, A3989SEVTR-T pinout, A3989SEVTR-T application, or A3989SEVTR-T equivalent, key selection criteria include its 36-pin QFN package with exposed thermal pad, dual-bridge architecture (three full bridges), synchronous rectification, thermal shutdown with hysteresis, and compatibility with industry-standard PHASE/ENABLE and I0/I1 stepper control logic.
Technical Context
The A3989SEVTR-T implements three independent N-channel DMOS full bridges - two for bipolar stepper winding control (Bridge 1 & 2) and one for DC motor drive (Bridge 3). Each bridge uses fixed 30 µs off-time PWM current regulation with blanking (1 µs for stepper, 3 µs for DC) to suppress false overcurrent detection during switching transients.
It features dual 2-bit nonlinear DACs for full/half/quarter-step sequencing, selectable fast/slow decay via MODE pin for DC operation, and mixed-decay mode for stepper operation (30.1% fast decay + remainder slow decay). Internal charge pump (CP1/CP2/VCP) enables high-side N-MOSFET gate drive above VBB, while synchronous rectification reduces power dissipation by replacing body-diode conduction with low-RDS(on) MOSFET paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 8–36 V - supports wide industrial input rails; pulsed rating up to 38 V for transient tolerance |
| Stepper Output Current | 1.2 A continuous - sufficient for NEMA 17–23 stepper motors in open-loop positioning |
| DC Motor Output Current | 2.4 A continuous - drives medium-power brushed DC motors without external FETs |
| On-Resistance (DC driver) | 350–450 mΩ - limits conduction loss to ≤1.3 V drop at 1.2 A, reducing heat generation |
| On-Resistance (stepper driver) | 700–800 mΩ - optimized for precision current control with external sense resistors |
| Fixed Off-Time | 30 µs - sets minimum PWM frequency (~33 kHz) and defines current decay timing window |
| Thermal Shutdown | 155–175 °C with 15 °C hysteresis - protects against sustained overload or poor heatsinking |
Pinout & Package
The A3989SEVTR-T is supplied in a lead-free 36-pin QFN package (6 mm × 6 mm × 0.9 mm) with exposed thermal pad (EV suffix), rated RθJA = 27 °C/W on 4-layer PCB per JEDEC standards.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OUT1A / OUT1B OUT2A / OUT2B OUT3A / OUT3B | DMOS full-bridge outputs | Drive stepper windings (Bridges 1 & 2) and DC motor (Bridge 3); each pair forms H-bridge with internal N-MOSFETs |
| SENSE1 / SENSE2 / SENSE3 | Current sense inputs | Monitor voltage across external sense resistors (RS1–RS3) to regulate phase current; max ±500 mV input range |
| VREF1 / VREF2 / VREF3 | Analog reference inputs | Set peak current trip level per bridge: ITRIP = VREF / (3 × RS); supports dynamic resolution scaling |
| PHASE1 / PHASE2 / PHASE3 I01 / I11 / I02 / I12 ENABLE / MODE | Digital control inputs | Industry-standard stepper interface (I0/I1/PHASE) + DC control (PHASE/ENABLE/MODE); MODE selects decay mode for DC bridge |
| VBB (pins 5, 23) | Load supply input | Dual VBB pins reduce IR drop and improve current sharing for high-power motor loads |
| GND (pins 16, 30) | Power ground | Separate ground pins minimize noise coupling between logic and power domains |
| CP1 / CP2 / VCP | Charge pump terminals | Generate boosted gate drive voltage (>VBB) for high-side N-MOSFETs; require 0.1 µF ceramic capacitors |
| PAD | Exposed thermal pad | Mandatory solder connection to PCB ground plane; serves as primary thermal path and star-ground reference point |
Key Features
| Feature | Design Value |
|---|---|
| Mixed-decay stepper control | 30.1% fast decay + remainder slow decay reduces motor noise, improves step linearity, and lowers power dissipation vs pure fast decay |
| Synchronous rectification | Replaces body-diode conduction with active MOSFET paths during current decay, cutting power loss by >40% under PWM operation |
| Dual 2-bit nonlinear DACs | Enable precise full/half/quarter-step sequencing without external microcontroller interpolation; supports modified step modes for torque optimization |
| Internal UVLO protection | VBB UVLO at 7.6 V ±0.3 V with 500 mV hysteresis prevents erratic operation during brown-out conditions |
| Crossover-current protection | 425 ns typical dead time prevents shoot-through during bridge switching transitions, enhancing reliability |
Applications
| Industrial CNC Positioning | Medical Infusion Pumps |
|---|---|
Use Scenario: Open-loop microstepping control of X/Y/Z axes in compact desktop CNC mills using NEMA 17 stepper motors. IC Role / Device Role / Timing Role: Dual-bridge stepper driver providing full/half/quarter-step resolution, current-regulated phase excitation, and mixed-decay timing control. Use Value: Enables smooth, quiet motion at low speeds (<100 RPM) with <±5% step error due to integrated DAC-based current profiling and blanking-compensated sensing. | Use Scenario: Precision volumetric delivery in portable infusion pumps requiring bidirectional DC motor control for syringe actuation. IC Role / Device Role / Timing Role: High-current DC motor driver with PHASE/ENABLE interface and fast/slow decay selection via MODE pin. Use Value: Delivers repeatable 0.1 mL/hr–100 mL/hr flow rates using 2.4 A continuous drive and synchronous rectification to maintain thermal stability in sealed enclosures. |
| Automated Test Equipment (ATE) | Printed Circuit Board Assembly (SMT Pick-and-Place) |
Use Scenario: Multi-axis motion control for probe positioning in semiconductor wafer testers with strict EMI and thermal constraints. IC Role / Device Role / Timing Role: Bipolar stepper driver with integrated thermal shutdown (165 °C trigger) and low-noise mixed-decay operation. Use Value: Maintains position accuracy within ±0.5 µm over 8-hour test cycles by limiting junction temperature rise to <90 °C via exposed-pad thermal design and synchronous rectification. | Use Scenario: High-speed component placement head using dual stepper motors for gantry and theta-Z motion in SMT machines. IC Role / Device Role / Timing Role: Dual-bridge stepper controller with independent VREF inputs enabling dynamic current scaling per axis. Use Value: Reduces motor heating during rapid acceleration/deceleration sequences by adjusting VREFx in real time, extending motor life and minimizing thermal drift in vision alignment systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bipolar stepper and high-current DC motor driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| A5989GEVTR-T | Successor device with identical pinout, enhanced thermal performance (RθJA = 24 °C/W), and extended operating temperature range (–40 to 125 °C). | Supports automotive-grade ambient conditions and higher continuous current capability in same footprint. | Select A5989GEVTR-T for new designs requiring production longevity, wider temperature range, or improved thermal margin. |
| TB6600HG | 6-phase stepper driver with higher voltage rating (45 V), but no integrated DC motor channel or synchronous rectification. | Requires external H-bridge for DC motor control; lacks mixed-decay and DAC-based microstepping. | Choose TB6600HG only when needing higher bus voltage or standalone high-power stepper control without DC motor integration. |
Compared with A3989SEVTR-T, the A5989GEVTR-T offers direct replacement capability with improved thermal specs and extended temperature range, while the TB6600HG provides higher voltage headroom but requires additional circuitry for DC motor control and lacks integrated decay optimization.
Availability
A3989SEVTR-T is available at Aetrix Electronics and suitable for legacy system repair, end-of-life component consolidation, and industrial equipment maintenance requiring stable component supply despite discontinuation status.
Supply support for A3989SEVTR-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 sensors and power ICs, specializing in motion control, current sensing, and motor driver solutions.
The A3989 product line was developed specifically for cost-sensitive, space-constrained embedded motion systems requiring integrated dual-motor drive capability with precision current regulation and thermal robustness.
FAQ
What is the functional status of the A3989SEVTR-T?
The A3989SEVTR-T is a discontinued product as of July 1, 2019, and is no longer in production. Allegro MicroSystems does not provide new samples, and the device should not be selected for new design applications. Aetrix Electronics maintains limited legacy stock for repair and maintenance use only, with full traceability and documentation for each unit shipped. Customers requiring long-term supply should transition to the recommended substitution A5989GEVTR-T.
Does the A3989SEVTR-T support microstepping, and how is it configured?
Yes, the A3989SEVTR-T supports full-step, half-step, and quarter-step microstepping via its dual 2-bit nonlinear DAC architecture. Step mode is selected using the I0x and I1x control inputs per bridge, while PHASEx determines direction. The DACs enable precise current profiling across steps - for example, quarter-step mode delivers 25%, 50%, 75%, and 100% of peak current per phase increment - all without external microcontroller interpolation. Configuration is static per step sequence table or dynamically adjustable via VREFx voltage modulation.
How does the A3989SEVTR-T manage thermal performance in high-current operation?
The A3989SEVTR-T relies on its 36-pin QFN package with exposed thermal pad (PAD) soldered directly to a PCB ground plane, achieving RθJA = 27 °C/W on a 4-layer board. Internal synchronous rectification reduces power dissipation by replacing body-diode conduction with low-RDS(on) MOSFET paths during current decay. Thermal shutdown activates at 165 °C (typical) with 15 °C hysteresis, and layout best practices - including star grounding under the PAD, short sense resistor traces, and thermal vias - are critical to sustaining 2.4 A DC or 1.2 A stepper current continuously.
Can the A3989SEVTR-T drive both a stepper motor and a DC motor simultaneously?
Yes, the A3989SEVTR-T integrates three independent full-bridge drivers: Bridges 1 and 2 are configured for bipolar stepper motor winding control (A/B phases), while Bridge 3 serves as a dedicated high-current DC motor driver. All bridges operate concurrently with independent current regulation via separate VREFx inputs and SENSEx feedback paths. Control logic is segregated - stepper operation uses I0x/I1x/PHASEx signals, while DC motor control uses PHASE3/ENABLE/MODE - enabling true simultaneous dual-motor motion control from a single IC.
What protection features are built into the A3989SEVTR-T?
The A3989SEVTR-T includes thermal shutdown with hysteresis (165 °C trigger, 15 °C recovery), undervoltage lockout on both VBB (7.6 V ±0.3 V) and VDD (2.8 V ±0.15 V), and crossover-current protection with 425 ns typical dead time. It also incorporates internal blanking (1 µs for stepper, 3 µs for DC) to prevent false overcurrent trips during switching transients, and synchronous rectification that disables near zero-current to avoid reverse current flow. No special power-up sequencing is required due to integrated charge pump delay (~200 µs) and robust UVLO behavior.
A3989SEVTR-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 36-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Motor Type - Stepper:
- Bipolar
- Motor Type - AC, DC:
- Brushed DC
- Function:
- Driver - Fully Integrated, Control and Power Stage
- Output Configuration:
- Half Bridge (6)
- Interface:
- Parallel
- Technology:
- DMOS
- Step Resolution:
- 1, 1/2, 1/4
- Applications:
- General Purpose
- Current - Output:
- 1.2A, 2.4A
- Voltage - Supply:
- 3V ~ 5.5V
- Voltage - Load:
- 8V ~ 36V
- Operating Temperature:
- -20°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-QFN (6x6)
A3989SEVTR-T FAQ
1.How can I place an order for A3989SEVTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A3989SEVTR-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 A3989SEVTR-T reliable?
The price and inventory of A3989SEVTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3989SEVTR-T is usually 5 days.
3.What payment methods are accepted for A3989SEVTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3989SEVTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3989SEVTR-T?
A3989SEVTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3989SEVTR-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 A3989SEVTR-T?
For technical support, including A3989SEVTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3989SEVTR-T requirements.
6.How does Aetrix verify that A3989SEVTR-T is sourced from the original manufacturer or authorized distributors?
All A3989SEVTR-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 A3989SEVTR-T meets industry standards.
7.What is the process for return or replacement of A3989SEVTR-T?
All A3989SEVTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A3989SEVTR-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 A3989SEVTR-T part is unused and in its original packaging.
Return procedure for A3989SEVTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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