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Allegro MicroSystems A3964SB
- Part No.:
- A3964SB
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 24-PowerDIP (0.300", 7.62mm)
- Datasheet:
-
A3964SB.pdf
- Description:
- IC MTRDRV BIPLR 4.75-5.25V 24DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,043
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Product details
Overview
A3964SB from Allegro MicroSystems is a dual full-bridge PWM motor driver IC designed for bipolar stepper motor control, delivering ±800 mA continuous output current per bridge at up to 30 V load supply voltage, with internal fixed off-time PWM current regulation, precision 2.5 V reference, and thermal shutdown protection - used in precision motion control systems requiring bidirectional torque and microstep-capable drive stages.
For engineers reviewing the A3964SB datasheet, A3964SB pinout, A3964SB application, or A3964SB equivalent, this page delivers verified technical context, package-specific pin mapping, real-world motor control use cases, and validated alternative options for bipolar stepper driver selection.
Technical Context
The A3964SB implements two independent full-bridge outputs with saturated sink drivers and internal transconductance-based PWM current control. Each bridge uses user-configurable RC timing networks (RT/CT) to set fixed off-time (27–33 µs typical), blanking window, and crossover delay - eliminating external filter networks on sense inputs.
It integrates a precision 2.5 V reference (±2% tolerance), internal UVLO (4.40 V disable threshold), thermal shutdown at 165°C with 15°C hysteresis, and crossover-current protection. PHASE/ENABLE logic controls polarity and enable state without power-up sequencing requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | ±800 mA continuous per bridge - supports mid-torque bipolar stepper motors without external heatsinking under typical ambient conditions. |
| Load Supply Voltage | Up to 30 V - compatible with common 24 V industrial motor rails and avoids need for intermediate DC-DC conversion. |
| PWM Fixed Off-Time | 27–33 µs (typ. 30 µs) - sets minimum decay interval and directly determines ripple current, EMI profile, and low-current regulation fidelity. |
| Reference Voltage | 2.45–2.55 V - enables accurate peak current setting via external sense resistor (RS) with <6 mV comparator offset. |
| Thermal Shutdown | 165°C junction temperature with 15°C hysteresis - protects against sustained overload or poor PCB thermal design while allowing brief transient overloads. |
| Logic Supply Range | 4.75–5.25 V - matches standard 5 V TTL/CMOS logic rails and includes UVLO with 0.125 V hysteresis for clean power-on reset. |
| Sink Saturation Voltage | 0.3–1.5 V at +500 to +800 mA - defines conduction loss and heat generation in low-side path during slow-decay PWM operation. |
Pinout & Package
The A3964SB is supplied in a 24-pin plastic DIP package with copper heat sink tabs (batwing leads) at ground potential - no electrical isolation required. Leads 6, 7, 18, and 19 are internally connected as shared ground terminals.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 18, 19, 20 | GROUND | Common power and logic ground return - multiple pins reduce IR drop and improve current sharing for thermal stability. |
| 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 | OUT1A, OUT1B, OUT2A, OUT2B, SENSE1, SENSE2, PHASE1, PHASE2, ENABLE1, ENABLE2 | Bridge output terminals, current sense inputs, polarity control, and per-bridge enable - direct interface to stepper coil windings and controller GPIO. |
| 21, 22, 23, 24 | VBB, VCC, PWM1, PWM2 | Motor supply input, logic supply input, and RC timing network connections - VBB handles high-current switching; PWMx pins accept RT/CT for off-time and blanking configuration. |
| 19, 20 | VREF(OUT), VREF(IN) | 2.5 V reference output and adjustable input - VREF(OUT) sources bias for external divider; VREF(IN) sets ITRIP = VREF(IN)/RS with transconductance accuracy. |
Key Features
| Feature | Design Value |
|---|---|
| Internal PWM current control | Fixed off-time architecture eliminates need for external PWM generator or current-sense amplifier - reduces BOM count and layout complexity. |
| Integrated 2.5 V reference | ±2% accuracy over temperature enables stable peak current setting without trimming or calibration - improves repeatability across production units. |
| Crossover-current protection | Hardware-enforced dead time prevents shoot-through during PHASE transitions - ensures safe switching without external timing logic. |
| RC-blanking function | Single CT capacitor sets both PWM off-time and comparator blanking window - suppresses false trips from diode reverse recovery and switching transients. |
| Thermal shutdown with hysteresis | 165°C trip + 15°C hysteresis allows recovery after transient overload without system latch-up - supports robust field operation. |
Applications
| Industrial CNC Positioning | Medical Infusion Pumps |
|---|---|
Use Scenario: Open-loop positioning of X-Y stage in benchtop CNC router using 1.8° hybrid stepper motors. IC Role / Device Role / Timing Role: Dual full-bridge driver executing PHASE/ENABLE commutation sequence to control coil polarity and current magnitude per step. Use Value: ±800 mA drive capability maintains holding torque at 200–400 steps/sec; internal PWM regulation ensures consistent microstep resolution without external DAC or chopper IC. | Use Scenario: Precise volumetric delivery in syringe-based infusion pump with bidirectional flow control. IC Role / Device Role / Timing Role: Bipolar stepper actuator driver regulating motor current via internal PWM to maintain constant plunger force across battery voltage variation. Use Value: 2.5 V reference and low-offset comparator enable ±3% current accuracy over 0–85°C - critical for dose consistency and regulatory compliance. |
| Lab Automation Sample Handlers | Print Head Carriage Control |
Use Scenario: Indexing carousel in automated ELISA analyzer moving multi-well plates between stations. IC Role / Device Role / Timing Role: Stepper driver managing acceleration/deceleration profiles via ENABLE PWM while maintaining torque through PHASE-controlled polarity reversal. Use Value: Internal thermal shutdown and UVLO prevent fault propagation during intermittent power brownouts - improves system uptime in shared lab power environments. | Use Scenario: Bidirectional carriage movement in thermal inkjet printer with rapid start/stop cycles. IC Role / Device Role / Timing Role: Full-bridge driver executing fast PHASE toggling to reverse direction while sustaining 800 mA peak current during print head acceleration. Use Value: Saturated sink drivers minimize conduction loss at 24 V rail - reduces junction temperature rise during high-duty-cycle printing sequences. |
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 |
|---|---|---|---|
| A3964SLB | Same silicon die, 20-lead SOIC-W package with identical electrical specs and pin-compatible functionality - differs only in footprint, thermal resistance (θJA = 60°C/W vs. 40°C/W for 'B'), and lead count. | Preferred for space-constrained PCBs where DIP insertion is impractical; requires different thermal pad layout and reflow profile. | Select A3964SLB when board area is limited and SOIC-W assembly is supported; retain same RC network and sense resistor values. |
| DRV8811PWPR | TI device with higher 1.5 A output rating, integrated current sense amplifier, and SPI interface - lacks internal 2.5 V reference and uses external PWM input instead of RC-based off-time control. | Better suited for closed-loop current monitoring or programmable off-time applications; requires additional MCU resources and external sensing components. | Choose DRV8811PWPR only if >800 mA drive or digital configurability is required - otherwise A3964SB offers simpler analog implementation with lower component count. |
Compared with A3964SLB, the A3964SB provides identical motor control functionality in a through-hole DIP package optimized for prototyping and thermal management via batwing leads; compared with DRV8811PWPR, it trades programmability and higher current for minimal external components and deterministic analog PWM timing.
Availability
A3964SB is available at Aetrix Electronics and suitable for industrial CNC positioning, medical infusion pumps, lab automation sample handlers, and print head carriage control requiring stable component supply and long-term obsolescence support.
Supply support for A3964SB 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 magnetic sensing and power ICs for motion control and energy-efficient systems.
The A3964SB belongs to Allegro's legacy motor driver product line engineered for cost-sensitive, high-reliability bipolar stepper applications in industrial and medical equipment - emphasizing analog simplicity, thermal robustness, and minimal external component count.
FAQ
What is the maximum continuous output current rating of the A3964SB?
The A3964SB supports ±800 mA continuous output current per bridge under specified thermal conditions (TA ≤ +85°C, adequate heatsinking). This rating assumes proper PCB copper area on batwing leads and adherence to absolute maximum junction temperature of +150°C. Peak pulsed current is ±1.0 A for ≤10 µs, but sustained operation above ±800 mA risks thermal shutdown activation.
Does the A3964SB require external current-sense resistors?
Yes, the A3964SB requires two external current-sense resistors (RS1 and RS2), one per bridge, connected between each SENSE pin and ground. The peak current limit ITRIP is calculated as VREF(IN)/RS, where VREF(IN) is set by a resistor divider from the internal 2.5 V reference. Sense resistor values must ensure the SENSE pin voltage does not exceed 1.0 V absolute maximum.
How is PWM off-time configured on the A3964SB?
PWM off-time on the A3964SB is set by an external RC network connected to the PWM1 and PWM2 pins - typically 30 kΩ resistor and 1000 pF capacitor yielding 30 µs nominal off-time. The same capacitor also determines the comparator blanking window duration, preventing false overcurrent detection during switching transitions.
What thermal protection features does the A3964SB include?
The A3964SB includes thermal shutdown that disables all drivers when junction temperature reaches +165°C (typical), with 15°C hysteresis to allow automatic recovery once temperature drops below +150°C. It also features crossover-current protection and undervoltage lockout (UVLO) that disables outputs if VCC falls below 4.40 V, preventing erratic operation during power ramp-up or brownout.
Can the A3964SB drive unipolar stepper motors?
No, the A3964SB is specifically designed for bipolar stepper motors and cannot directly drive unipolar steppers. Its dual full-bridge topology provides four quadrant control (forward/reverse current in each winding), whereas unipolar motors require center-tapped windings and single-polarity drive per phase. Using A3964SB with unipolar motors would require rewiring or external diode networks and is not supported by Allegro's design intent or characterization data.
A3964SB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 24-PowerDIP (0.300", 7.62mm)
- 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:
- 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:
- Through Hole
- Supplier Device Package:
- 24-DIP
A3964SB FAQ
1.How can I place an order for A3964SB through Aetrix?
Please submit a Request for Quotation (RFQ) for A3964SB 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 A3964SB reliable?
The price and inventory of A3964SB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3964SB is usually 5 days.
3.What payment methods are accepted for A3964SB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3964SB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3964SB?
A3964SB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3964SB 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 A3964SB?
For technical support, including A3964SB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3964SB requirements.
6.How does Aetrix verify that A3964SB is sourced from the original manufacturer or authorized distributors?
All A3964SB 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 A3964SB meets industry standards.
7.What is the process for return or replacement of A3964SB?
All A3964SB units undergo pre-shipment inspection (PSI). If there is an issue with A3964SB, 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 A3964SB part is unused and in its original packaging.
Return procedure for A3964SB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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