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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Motor Drivers, Controllers

Allegro MicroSystems A3964SLBTR-T

Name: A3964SLBTR-T
Brand: Allegro MicroSystems
SKU: A3964SLBTR-T
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: A3964SLBTR-T

Manufacturer:: Allegro MicroSystems

Category:: Motor Drivers, Controllers

Package:: 20-SOIC (0.295", 7.50mm Width)

Datasheet:: A3964SLBTR-T.pdf

Description:: IC MOTOR DRIVER BIPOLAR 20SOIC

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Product details

Overview

A3964SLBTR-T from Allegro MicroSystems is a dual full-bridge PWM motor driver IC designed for bipolar stepper motor current control via fixed off-time PWM regulation. It delivers ±800 mA continuous output current per bridge, supports up to 30 V load supply voltage, and integrates a precision 2.5 V reference and internal thermal shutdown. It is used in motion control systems requiring precise microstepping hold current and bidirectional torque regulation.

For engineers reviewing the A3964SLBTR-T datasheet, A3964SLBTR-T pinout, A3964SLBTR-T application, or A3964SLBTR-T equivalent, key selection criteria include its 20-pin SOIC (LB) package with internally fused power pins, dual independent PWM current-control channels, RC-programmable off-time and blanking window, and integrated crossover-current protection for reliable stepper motor phase switching.

Technical Context

The A3964SLBTR-T implements two independent fixed off-time PWM current-control loops, each using an external RC network (RT/CT) to set t_OFF (27–33 μs typical) and comparator blanking time. Current trip level (I_TRIP) is set by V_REF(IN)/R_S, where V_REF(IN) is derived from the internal 2.5 V reference via user-selected resistor divider (3–15 kΩ).

Each bridge features PHASE-controlled polarity selection and ENABLE-gated output disable, with propagation delays under 3.2 μs. Internal protection includes UVLO (4.40 V disable threshold), thermal shutdown at 165°C with 15°C hysteresis, and saturated sink drivers with V_CE(SAT) ≤ 0.6 V at ±500 mA.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Current	±800 mA continuous per bridge - enables driving NEMA 11–14 stepper motors without external heatsinking under typical ambient conditions.
Load Supply Voltage	5–30 V - supports 12 V and 24 V industrial motor rails with 33 V absolute max rating for transient robustness.
Reference Voltage	2.45–2.55 V (25°C) - provides stable I_TRIP accuracy across temperature, reducing need for calibration in closed-loop current control.
PWM Off-Time	27–33 μs (typical, CT = 1000 pF, RT = 30 kΩ) - sets minimum current decay interval and defines audible noise floor and ripple trade-off.
Thermal Shutdown	165°C junction, 15°C hysteresis - protects against sustained overload or poor PCB copper layout while allowing brief peak currents.
Logic Supply Range	4.75–5.25 V - ensures compatibility with standard 5 V microcontroller GPIO and eliminates need for level-shifting logic interface.
UVLO Threshold	4.40 V (decreasing V_CC) - prevents erratic operation during brown-out or slow power-up sequences.

Pinout & Package

Package: 20-pin SOICW (suffix LB), lead-free with 100% matte tin plating; internally fused pins 5, 6, 15, and 16 enhance thermal dissipation from batwing-style power terminals.

Pin/Terminal	Circuit Role	Design Meaning
VBB (Pin 1)	Motor supply input	High-current input for both bridges; must be decoupled with ≥47 μF electrolytic capacitor near pin.
VCC (Pin 2)	Logic supply input	5 V digital supply; powers internal logic, reference, and comparators - requires local 0.1 μF bypass.
OUT1A/OUT1B (Pins 3,4)	Bridge 1 output pair	Drive one stepper coil; outputs switch between VBB and GND via source/sink drivers with integrated clamp diodes.
SENSE1 (Pin 5)	Bridge 1 current sense input	High-side sensing node; accepts differential voltage up to 1.0 V across external R_S to trigger PWM current limit.
PHASE1 (Pin 6)	Bridge 1 polarity control	Digital input selecting current direction (H→forward, L→reverse); determines which driver pair (OUT1A/OUT1B) is active.
ENABLE1 (Pin 7)	Bridge 1 enable control	Active-high input disabling both OUT1A/OUT1B drivers; used for microstepping current scaling or sleep mode.
RC1 (Pin 8)	Bridge 1 PWM timing node	Connects external RT/CT network; sets t_OFF and comparator blanking window - CT also discharges during PHASE/ENABLE transitions.
GROUND (Pins 9,10,11,12)	Power and logic ground	Four dedicated GND pins minimize IR drop; high-current paths (pins 9–10) and logic grounds (pins 11–12) should be separated on PCB.
OUT2A/OUT2B (Pins 13,14)	Bridge 2 output pair	Drives second stepper coil independently; identical electrical specs and layout requirements as Bridge 1.
SENSE2 (Pin 15)	Bridge 2 current sense input	Same function as SENSE1; requires separate low-IR ground return to avoid cross-talk between bridges.
PHASE2 (Pin 16)	Bridge 2 polarity control	Independent control of second coil direction; allows full bipolar stepping (e.g., wave, full, half-step) without external logic.
ENABLE2 (Pin 17)	Bridge 2 enable control	Enables/disables Bridge 2 independently - essential for asymmetric current profiles or dynamic torque balancing.
RC2 (Pin 18)	Bridge 2 PWM timing node	Independent RC network for Bridge 2; permits different t_OFF values per bridge to optimize performance per coil impedance.
VREF(OUT) (Pin 19)	Internal reference output	2.5 V precision voltage source; drives external resistor divider to set VREF(IN); max load 900 μA.
VREF(IN) (Pin 20)	Reference input for current limit	Comparator input setting I_TRIP; voltage range –0.3 to 1.0 V - must be filtered and isolated from power ground noise.

Key Features

Feature	Design Value
Dual independent PWM current control	Each bridge has separate RC timing (RC1/RC2) and current sense (SENSE1/SENSE2), enabling asymmetric current regulation for non-identical coils or dynamic load compensation.
Integrated 2.5 V reference with 150–900 μA drive capability	Eliminates need for external reference IC; supports direct resistor-divider programming of I_TRIP with <±2% error over temperature when RD = 3–15 kΩ.
RC-programmable comparator blanking	Single CT capacitor sets both PWM off-time and blanking window, preventing false overcurrent trips during PHASE/ENABLE transitions or diode reverse recovery.
Internally fused SOICW power pins	Pins 5, 6, 15, 16 are internally fused to reduce thermal resistance; enables 20% higher power dissipation than standard SOIC without external heatsink.
Crossover-current protection with dead time	Prevents shoot-through during PHASE transitions by enforcing minimum delay between source/sink driver switching - no external timing components required.

Applications

Industrial CNC Positioning	Medical Infusion Pump Actuation
Use Scenario: Precise open-loop positioning of X/Y stages in desktop CNC mills using 1.8° bipolar stepper motors. IC Role / Device Role / Timing Role: Dual full-bridge driver executing microstepping waveforms; PHASE/ENABLE PWM regulates holding torque and reduces audible noise during dwell periods. Use Value: ±800 mA per bridge sustains detent torque at rest; RC-blanking prevents false current-limit trips during rapid direction reversals common in G-code path planning.	Use Scenario: Bidirectional syringe actuation in portable infusion pumps requiring smooth, low-vibration fluid delivery. IC Role / Device Role / Timing Role: Motor driver implementing closed-loop current control via external microcontroller feedback; VREF(IN) dynamically adjusted to maintain constant flow rate across battery voltage decay. Use Value: Internal 2.5 V reference stability ensures <±3% current accuracy from 3.3 V to 5.5 V logic supply, critical for dosage consistency over full battery life.
Automated Laboratory Robotics	3D Printer Extruder Control
Use Scenario: Multi-axis sample handling in automated PCR workstations where stepper-driven grippers require repeatable force and silent operation. IC Role / Device Role / Timing Role: Dual-bridge controller managing independent coil currents for torque vectoring; ENABLE PWM modulates average current to adjust grip strength without mechanical sensors. Use Value: Independent RC1/RC2 networks allow tuning t_OFF per axis - shorter off-time for fast-response gripper, longer for high-torque carousel rotation.	Use Scenario: High-speed filament feeding in FDM 3D printers where extruder stepper must respond instantly to acceleration commands without step loss. IC Role / Device Role / Timing Role: Full-bridge driver executing real-time current profiling; PHASE PWM maintains continuous coil current during direction changes to prevent resonance-induced missed steps. Use Value: Propagation delay <3.2 μs ensures sub-microsecond response to microcontroller STEP/DIR signals, supporting >20 kHz step rates in closed-loop extrusion control.

Industrial CNC Positioning

Medical Infusion Pump Actuation

Use Scenario: Precise open-loop positioning of X/Y stages in desktop CNC mills using 1.8° bipolar stepper motors.

IC Role / Device Role / Timing Role: Dual full-bridge driver executing microstepping waveforms; PHASE/ENABLE PWM regulates holding torque and reduces audible noise during dwell periods.

Use Value: ±800 mA per bridge sustains detent torque at rest; RC-blanking prevents false current-limit trips during rapid direction reversals common in G-code path planning.

Use Scenario: Bidirectional syringe actuation in portable infusion pumps requiring smooth, low-vibration fluid delivery.

IC Role / Device Role / Timing Role: Motor driver implementing closed-loop current control via external microcontroller feedback; VREF(IN) dynamically adjusted to maintain constant flow rate across battery voltage decay.

Use Value: Internal 2.5 V reference stability ensures <±3% current accuracy from 3.3 V to 5.5 V logic supply, critical for dosage consistency over full battery life.

Automated Laboratory Robotics

3D Printer Extruder Control

Use Scenario: Multi-axis sample handling in automated PCR workstations where stepper-driven grippers require repeatable force and silent operation.

IC Role / Device Role / Timing Role: Dual-bridge controller managing independent coil currents for torque vectoring; ENABLE PWM modulates average current to adjust grip strength without mechanical sensors.

Use Value: Independent RC1/RC2 networks allow tuning t_OFF per axis - shorter off-time for fast-response gripper, longer for high-torque carousel rotation.

Use Scenario: High-speed filament feeding in FDM 3D printers where extruder stepper must respond instantly to acceleration commands without step loss.

IC Role / Device Role / Timing Role: Full-bridge driver executing real-time current profiling; PHASE PWM maintains continuous coil current during direction changes to prevent resonance-induced missed steps.

Use Value: Propagation delay <3.2 μs ensures sub-microsecond response to microcontroller STEP/DIR signals, supporting >20 kHz step rates in closed-loop extrusion control.

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual full-bridge PWM motor driver applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
TB6600HG	Higher 4.5 A peak current, external current-sense resistors required, no integrated reference, larger HTSSOP-28 package.	Targeted at high-power NEMA 23+ steppers; lacks RC-blanking and internal reference, increasing BOM count and layout complexity.	Choose TB6600HG only when >±1.5 A per bridge is required and board space allows larger package; A3964SLBTR-T offers lower system cost for sub-1 A applications.
DRV8825	Integrated current DAC, 2.2 A peak, 3.3/5 V logic compatible, but no internal reference or RC-blanking; uses external oscillator for PWM.	Optimized for compact 3D printer boards with microstepping resolution up to 1/32; lacks analog current programming flexibility and comparator blanking for noisy environments.	Prefer DRV8825 for space-constrained designs needing high microstep resolution; A3964SLBTR-T is superior for industrial settings with EMI or where analog current tuning is preferred.

Compared with TB6600HG and DRV8825, the A3964SLBTR-T provides unique integration of precision internal reference, RC-programmable blanking, and fused SOICW thermal design - making it optimal for cost-sensitive, noise-immune, medium-current stepper control where layout simplicity and reliability outweigh raw current headroom.

Availability

A3964SLBTR-T is available at Aetrix Electronics and suitable for industrial CNC positioning, medical infusion pump actuation, automated laboratory robotics, and 3D printer extruder control requiring stable component supply and long-term production continuity.

Supply support for A3964SLBTR-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 A3964 product line was designed specifically for bipolar stepper motor current regulation in cost-sensitive, thermally constrained embedded systems - emphasizing integration of reference, protection, and programmable timing to reduce external component count.

FAQ

What is the maximum continuous output current supported by the A3964SLBTR-T?

The A3964SLBTR-T supports ±800 mA continuous output current per bridge at T_A = 85°C with adequate PCB copper area. This rating assumes proper thermal management - including use of the internally fused batwing pins and ≥6 cm² of 2-oz copper connected to pins 5, 6, 15, and 16. Exceeding this current continuously risks activation of thermal shutdown at 165°C junction temperature.

How does the A3964SLBTR-T implement PWM current control without an external oscillator?

The A3964SLBTR-T uses an internal fixed off-time PWM architecture where the off-time (t_OFF) is set by an external RC network connected to pins RC1 and RC2. The capacitor CT also serves as the blanking timer for the current-sense comparator, eliminating the need for separate filter networks. This self-timed design simplifies layout and improves noise immunity compared to externally clocked drivers.

Can the A3964SLBTR-T drive unipolar stepper motors?

No, the A3964SLBTR-T is designed exclusively for bipolar stepper motors with center-tapped or dual-winding configurations. Its dual full-bridge topology requires four terminals per coil and cannot interface with the five- or six-wire unipolar motor wiring scheme. Attempting to connect a unipolar motor may result in incorrect phasing or damage due to improper current paths.

What is the purpose of the internally fused pins on the A3964SLBTR-T SOIC package?

The internally fused pins (5, 6, 15, 16) on the A3964SLBTR-T's 20-pin SOICW package reduce thermal resistance between the die and PCB copper by creating low-impedance thermal pathways. This design improves power dissipation by ~20–30% versus standard SOIC, allowing higher continuous current operation without external heatsinking - critical for compact industrial motion control modules.

Does the A3964SLBTR-T require external flyback diodes for inductive load protection?

No, the A3964SLBTR-T integrates internal transient-suppression diodes across each output pair (OUT1A/OUT1B and OUT2A/OUT2B). These diodes provide flyback current recirculation during PWM off-time and protect against inductive kickback. External diodes are optional and only recommended in high-frequency or high-current applications where faster recovery (<200 ns) is needed to reduce switching losses.

A3964SLBTR-T Specifications

Product attributes: Attribute value

Manufacturer:: Allegro MicroSystems

Series:: -

Package/Case:: 20-SOIC (0.295", 7.50mm Width)

Packaging:: Tape & Reel (TR)

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:: Parallel

Technology:: Bipolar

Step Resolution:: -

Applications:: General Purpose

Current - Output:: 800mA

Voltage - Supply:: 4.75V ~ 5.25V

Voltage - Load:: 5V ~ 30V

Operating Temperature:: -20°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-SOIC

A3964SLBTR-T FAQ

1.How can I place an order for A3964SLBTR-T through Aetrix?

Please submit a Request for Quotation (RFQ) for A3964SLBTR-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 A3964SLBTR-T reliable?

The price and inventory of A3964SLBTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3964SLBTR-T is usually 5 days.

3.What payment methods are accepted for A3964SLBTR-T?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3964SLBTR-T transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for A3964SLBTR-T?

A3964SLBTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your A3964SLBTR-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 A3964SLBTR-T?

For technical support, including A3964SLBTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3964SLBTR-T requirements.

6.How does Aetrix verify that A3964SLBTR-T is sourced from the original manufacturer or authorized distributors?

All A3964SLBTR-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 A3964SLBTR-T meets industry standards.

7.What is the process for return or replacement of A3964SLBTR-T?

All A3964SLBTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A3964SLBTR-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 A3964SLBTR-T part is unused and in its original packaging.

Return procedure for A3964SLBTR-T:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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