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Allegro MicroSystems A3986SLDTR-T
- Part No.:
- A3986SLDTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 38-TFSOP (0.173", 4.40mm Width)
- Datasheet:
-
A3986SLDTR-T.pdf
- Description:
- IC MTR DRV BIPOLR 3-5.5V 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,606
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Product details
Overview
A3986SLDTR-T from Allegro MicroSystems is a dual full-bridge N-channel MOSFET gate driver with integrated microstepping translator, designed for bipolar 2-phase stepper motors (30–500 W) operating at 12–50 V supply voltage. It delivers fixed off-time PWM current control, synchronous rectification, and supports full/half/quarter/sixteenth-step resolution via STEP/DIR interface.
For engineers reviewing the A3986SLDTR-T datasheet, A3986SLDTR-T pinout, A3986SLDTR-T application, or A3986SLDTR-T equivalent, this device enables simplified motor control in industrial automation, CNC equipment, and precision positioning systems where low audible noise, high step accuracy, and external MOSFET flexibility are required.
Technical Context
The A3986SLDTR-T implements two independent sinusoidal DACs to generate phase-specific reference voltages for fixed-off-time PWM current controllers, enabling precise microstepping waveforms. Its translator logic interprets STEP/DIR/MS1/MS2 inputs to sequence DAC outputs without external microcontroller intervention.
Gate drive uses bootstrap capacitors for high-side N-MOSFET biasing, with programmable dead time (0.6–1.2 μs), blanking (1.2–1.8 μs), and mixed-decay control via PFD1/PFD2 pins. Protection includes thermal shutdown (165 °C), VREG/VDD undervoltage lockout, and cross-conduction prevention.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 12–50 V - powers external N-MOSFET bridges and internal regulator; supports wide industrial motor bus voltages. |
| Microstep Resolution | Full / Half / Quarter / Sixteenth - selected by MS1/MS2 logic inputs; eliminates need for external sequencing firmware. |
| PWM Fixed Off-Time | 18.12–23.16 μs - sets current decay duration; adjustable via ROSC resistor to optimize torque/noise trade-off. |
| Current Control Accuracy | ±5% trip point error - ensures consistent phase current regulation across temperature and supply variations. |
| Gate Drive Rise/Fall Time | 80–160 ns / 40–80 ns - enables fast switching of external power MOSFETs while minimizing shoot-through risk. |
| Thermal Shutdown Threshold | 165 °C - protects device under overload or poor heatsinking; 15 °C hysteresis prevents oscillation. |
| Oscillator Frequency | 3.2–4.8 MHz - determines timing resolution for dead time, blanking, and off-time; set by external ROSC resistor. |
Pinout & Package
Package: 38-pin TSSOP (suffix LD), lead-free, 100% matte tin leadframe plating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| STEP | Step command input | Low-to-high transition advances motor one microstep; no external timing or phase tables required. |
| DIR | Direction control input | Logic level sets rotation direction; change takes effect on next STEP edge. |
| MS1, MS2 | Microstep resolution select | Binary-encoded selection of full/half/quarter/sixteenth-step mode per Table 1. |
| PFD1, PFD2 | Mixed-decay fast-decay ratio control | Selects 0%, 8%, 26%, or 100% fast-decay portion during falling current to suppress BEMF distortion. |
| GH1A–GH2B | High-side gate drivers | Drive gates of external N-MOSFETs; require bootstrap capacitors (CBOOTx) referenced to Sxx pins. |
| GL1A–GL2B | Low-side gate drivers | Sink current from low-side N-MOSFET gates; referenced to LSS1/LSS2 return paths. |
| SENSE1, SENSE2 | Current sense inputs | Monitor voltage across external RSENSE resistors to regulate phase current via PWM comparator. |
| VREF | Reference voltage input | Sets maximum peak current ITRIP(max) = VREF/(8 × RSENSE); internally limited to 2 V with 20 kΩ pull-up. |
| VREG | Internal 11.25–13 V regulator output | Supplies low-side drivers and charges bootstrap capacitors; monitored for UVLO protection. |
| ENABLE | Global output enable | Logic high disables all gate outputs; translator logic remains active for state retention. |
| RESET | Translator reset and sleep control | Active-low pulse resets DAC to home position; sustained high enables normal operation. |
Key Features
| Feature | Design Value |
|---|---|
| 2-wire step-and-direction interface | Eliminates complex microcontroller firmware; single STEP pulse drives one microstep at selected resolution. |
| Integrated sinusoidal DAC translator | Generates precise 16-step sine/cosine current references per phase; enables smooth motion and reduced resonance. |
| Adjustable mixed-decay control | Automatically switches between slow/fast decay based on current direction; suppresses BEMF-induced distortion at high speed. |
| Synchronous rectification (SR pin) | Reduces power dissipation by replacing body diode conduction with low-RDS(ON) MOSFET paths during decay. |
| Cross-conduction protection | Programmable dead time (0.6–1.2 μs) prevents shoot-through in external full-bridges. |
| Comprehensive fault protection | Includes thermal shutdown (165 °C), VREG/VDD UVLO, and internal current limiting - no external supervision needed. |
Applications
| Industrial CNC Positioning | Medical Infusion Pumps |
|---|---|
Use Scenario: Precision linear actuation in multi-axis CNC routers requiring sub-micron repeatability and low vibration. IC Role / Device Role / Timing Role: Dual full-bridge gate driver with microstepping translator; generates synchronized sinusoidal current waveforms for two motor phases. Use Value: Sixteenth-step resolution and mixed-decay control reduce positional error and audible noise, improving surface finish quality. |
Use Scenario: Controlled fluid delivery in portable infusion pumps where silent operation and accurate flow rate are critical. IC Role / Device Role / Timing Role: Stepper motor controller with fixed off-time PWM and synchronous rectification; regulates phase current to maintain constant torque at low speeds. Use Value: Low ripple current and thermal shutdown ensure safe, reliable dosing without audible motor whine disturbing patients. |
| Automated Laboratory Equipment | 3D Printer Extruder Control |
Use Scenario: Sample handling robotics requiring repeatable angular positioning of grippers and pipette arms. IC Role / Device Role / Timing Role: Translator-based stepper driver with STEP/DIR interface; sequences DAC outputs to drive bipolar 2-phase motors. Use Value: Full/half/quarter-step modes allow flexible resolution matching; ENABLE pin enables rapid motor disable for safety interlocks. |
Use Scenario: High-speed filament extrusion in fused deposition modeling (FDM) printers demanding responsive acceleration/deceleration. IC Role / Device Role / Timing Role: External N-MOSFET driver with adjustable off-time and mixed-decay; manages back-EMF during rapid direction changes. Use Value: Fast-decay capability at high step rates maintains torque consistency; bootstrap gate drive supports 50 V motor supplies for increased extrusion force. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual full-bridge stepper driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| A4989 | Successor device with enhanced thermal performance (RθJA = 40 °C/W), integrated charge pump (no bootstrap caps), and improved current regulation linearity (±3%). | Supports higher continuous current and faster step rates; recommended for new designs requiring extended lifetime or higher reliability. | Select A4989 for new designs - it replaces A3986SLDTR-T with no layout changes and superior specs. |
| TB6600HG | Single-chip solution with integrated power MOSFETs (4.5 A), fixed 1/8–1/32 microstepping, and no external DAC or oscillator tuning. | Limited to lower-power motors (<100 W); lacks mixed-decay adjustment and bootstrap flexibility of A3986SLDTR-T. | Choose TB6600HG only for cost-sensitive, low-complexity applications where external MOSFETs are unnecessary. |
Compared with A4989 and TB6600HG, the A3986SLDTR-T offers unmatched flexibility in external MOSFET selection, fine-grained decay control, and wide supply range (12–50 V), making it ideal for legacy industrial systems where field-replaceability and thermal design reuse are priorities - though not recommended for new designs per Allegro's obsolescence notice.
Availability
A3986SLDTR-T is available at Aetrix Electronics and suitable for industrial CNC positioning, medical infusion pumps, automated laboratory equipment, and 3D printer extruder control requiring stable component supply despite its Not for New Design status.
Supply support for A3986SLDTR-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, specializing in motion control, current sensing, and motor driver solutions for industrial and automotive markets.
The A3986SLDTR-T belongs to Allegro's stepper motor driver product line, engineered specifically for high-efficiency, low-noise bipolar stepper control using external N-channel MOSFETs in demanding industrial environments.
FAQ
What is the recommended replacement for A3986SLDTR-T in new designs?
The A4989 is Allegro's officially recommended successor to the A3986SLDTR-T for new designs. It features an integrated charge pump eliminating bootstrap capacitors, improved thermal resistance (40 °C/W vs. 51 °C/W), and tighter current regulation (±3% vs. ±5%). The A3986SLDTR-T remains viable for existing production but is classified Not for New Design per Allegro's January 2012 notice.
Does A3986SLDTR-T support sixteenth-step microstepping?
Yes, the A3986SLDTR-T supports sixteenth-step microstepping via the MS1 and MS2 inputs configured to logic high (1,1). Its integrated translator automatically sequences the dual sinusoidal DACs to produce 16 precise current levels per electrical cycle, as defined in Table 3 of the datasheet. This enables smooth, low-vibration motor operation at high resolution.
How does the mixed-decay function work in A3986SLDTR-T?
The A3986SLDTR-T implements mixed-decay by automatically selecting fast-decay when phase current is decreasing (to counteract BEMF-induced distortion) and slow-decay when current is increasing (to minimize ripple). The PFD1/PFD2 pins define the fast-decay portion (0%, 8%, 26%, or 100%) during falling current, per Table 2. This dynamic control improves step accuracy and reduces audible noise across speed ranges.
What is the purpose of the VREF pin on A3986SLDTR-T?
The VREF pin on the A3986SLDTR-T sets the maximum peak phase current via ITRIP(max) = VREF / (8 × RSENSE). It accepts an external reference voltage up to 2 V (internally clamped with a 20 kΩ pull-up to VDD). The internal DAC divides VREF by 8 to generate the current-sense comparator reference, enabling precise scaling of motor torque through simple resistor selection.
Can A3986SLDTR-T drive P-channel high-side MOSFETs?
No, the A3986SLDTR-T is designed exclusively for N-channel MOSFETs in both high-side and low-side positions. Its high-side gate drivers (GHxx) use bootstrap capacitors to generate gate voltages above VBB, which is incompatible with P-channel devices requiring gate drive below source potential. External P-MOSFETs would require redesign of the gate drive topology and are not supported.
A3986SLDTR-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Motor Type - Stepper:
- Bipolar
- Motor Type - AC, DC:
- -
- Function:
- Controller - Commutation, Direction Management
- Output Configuration:
- Pre-Driver - Half Bridge (4)
- Interface:
- Logic
- Technology:
- Power MOSFET
- Step Resolution:
- 1, 1/2, 1/4, 1/16
- Applications:
- General Purpose
- Current - Output:
- -
- Voltage - Supply:
- 3V ~ 5.5V
- Voltage - Load:
- 12V ~ 50V
- Operating Temperature:
- -20°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-TSSOP
A3986SLDTR-T FAQ
1.How can I place an order for A3986SLDTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A3986SLDTR-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 A3986SLDTR-T reliable?
The price and inventory of A3986SLDTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3986SLDTR-T is usually 5 days.
3.What payment methods are accepted for A3986SLDTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3986SLDTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3986SLDTR-T?
A3986SLDTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3986SLDTR-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 A3986SLDTR-T?
For technical support, including A3986SLDTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3986SLDTR-T requirements.
6.How does Aetrix verify that A3986SLDTR-T is sourced from the original manufacturer or authorized distributors?
All A3986SLDTR-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 A3986SLDTR-T meets industry standards.
7.What is the process for return or replacement of A3986SLDTR-T?
All A3986SLDTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A3986SLDTR-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 A3986SLDTR-T part is unused and in its original packaging.
Return procedure for A3986SLDTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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