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Allegro MicroSystems A3966SA
- Part No.:
- A3966SA
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
A3966SA.pdf
- Description:
- IC MTR DRV BIPLR 4.75-5.5V 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,991
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Product details
Overview
A3966SA from Allegro MicroSystems is a dual full-bridge PWM motor driver IC designed to control both windings of a two-phase bipolar stepper motor, delivering ±650 mA continuous output current per bridge at up to 30 V load supply voltage, with internal fixed-frequency current regulation and Satlington® sink drivers for low saturation voltage and high peak-current capability in industrial motion control systems.
For engineers reviewing the A3966SA datasheet, A3966SA pinout, A3966SA application, or A3966SA equivalent, key selection considerations include its 16-pin SOICW (LB) package, user-configurable RC-timed PWM frequency (25.4 kHz typical), blanking window control, thermal shutdown (165 °C), and crossover-current protection - all critical for reliable stepper actuation in embedded motion platforms.
Technical Context
The A3966SA integrates two independent full-bridge power stages, each controlled by separate PHASE and ENABLE inputs, with internal PWM current regulation using a fixed-frequency oscillator set by external RT/CT components (56 kΩ/680 pF yields 25.4 kHz). Current sensing is performed via external resistors referenced to VREF, with trip threshold defined as ITRIP = VREF/(4 × RS) + ISO (ISO = 18 mA typical).
Each bridge features Satlington® sink drivers (0.3–1.3 V saturation at 400–650 mA), ground-clamp and flyback diodes, UVLO (4.1–4.6 V enable threshold), and 1 µs internally generated dead time to prevent shoot-through. Thermal shutdown activates at TJ = 165 °C with 15 °C hysteresis, and logic supply operates from 4.75–5.5 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | ±650 mA continuous per bridge - supports mid-torque bipolar stepper motors without external heatsinking at TA ≤ 85 °C. |
| Load Supply Voltage | 30 V max - enables direct interface with 24 V industrial power rails and accommodates back-EMF spikes. |
| PWM Frequency | 25.4 kHz typical (RT = 56 kΩ, CT = 680 pF) - balances ripple current reduction against switching loss and EMI. |
| Saturation Voltage | Sink: 0.3–1.3 V (400–650 mA); Source: 1.7–2.1 V - minimizes on-state power dissipation in full-bridge conduction paths. |
| Thermal Shutdown | 165 °C junction temperature with 15 °C hysteresis - provides self-protection during overload or poor PCB thermal design. |
| Logic Supply Range | 4.75–5.5 V - compatible with standard 5 V microcontroller I/O and ensures robust noise immunity. |
| UVLO Threshold | 4.1–4.6 V rising edge - prevents erratic operation during brown-out conditions on VCC rail. |
Pinout & Package
Package: 16-pin SOICW (suffix LB), with pins 4 and 13 internally fused to the die pad for enhanced thermal dissipation; leads are 100% matte tin plated, Pb-free.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OUT1A, OUT1B OUT2A, OUT2B |
Bridge Output Terminals | Drive motor winding A and B respectively; each pair forms one full-bridge leg with complementary sourcing/sinking capability. |
| PHASE1, PHASE2 | Polarity Control Input | Determines current direction per bridge: high → OUTA to OUTB; low → OUTB to OUTA; enables full-step and half-step sequencing. |
| ENABLE1, ENABLE2 | Bridge Enable Input | Active-low; high disables both drivers in respective bridge, forcing fast decay via internal clamp/flyback diodes. |
| SENSE1, SENSE2 | Current-Sense Input | Connects to external sense resistor (RS); feeds current-comparator input with offset-compensated signal for PWM trip detection. |
| VREF | Reference Voltage Input | 0–2 V input; internally divided by 4 to set current-comparator threshold (ITRIP = VREF/(4 × RS) + 18 mA). |
| RC | Oscillator Timing Input | Connects external RT/CT network; sets PWM frequency and blanking window duration (tblank = 1900 × CT). |
| VBB | Load Supply Input | High-side power rail (up to 30 V); supplies H-bridge power transistors; requires local 47 µF decoupling. |
| VCC | Logic Supply Input | 5 V logic rail; powers internal logic, comparators, and gate drivers; must be stable within 4.75–5.5 V range. |
| GROUND | Power & Signal Ground | Common reference for VBB return, sense resistor, logic, and die pad; pins 4 & 13 tied internally to this node. |
Key Features
| Feature | Design Value |
|---|---|
| Satlington® sink drivers | Combines <0.5 V saturation at 400 mA with Darlington-level peak current handling - reduces conduction loss while maintaining drive strength. |
| User-selectable blanking window | tblank = 1900 × CT (e.g., 1.3 µs at 680 pF) - suppresses false PWM latch resets caused by switching transients and diode reverse recovery. |
| Integrated protection circuitry | Includes UVLO, thermal shutdown (165 °C), crossover-current prevention, and internal ground-clamp/flyback diodes - eliminates need for external protection components. |
| Independent bridge control | Separate PHASE/ENABLE per bridge allows asymmetric stepping modes, microstepping with external controllers, and dynamic torque balancing. |
| Fixed-frequency PWM current control | RC-set oscillator (22.9–27.9 kHz) enables predictable current ripple and simplified EMI filtering versus variable-frequency alternatives. |
Applications
| Industrial CNC Positioning | Medical Infusion Pumps |
|---|---|
|
Use Scenario: Precise open-loop positioning of X/Y axes in desktop CNC mills using NEMA 17 bipolar stepper motors. IC Role / Device Role / Timing Role: Dual full-bridge driver executing step/direction commands from MCU; regulates phase current to maintain torque across speed range. Use Value: ±650 mA drive capability and 30 V headroom support 24 V motor operation with margin for back-EMF; thermal shutdown prevents fault propagation during stall. |
Use Scenario: Controlled syringe advancement in battery-powered portable infusion devices requiring silent, repeatable microstep motion. IC Role / Device Role / Timing Role: Stepper driver receiving pulse-width-modulated ENABLE signals for fine-grained current decay control and smooth low-speed operation. Use Value: Blanking window and fixed-frequency PWM minimize audible motor whine; low VCE(sat) extends battery life by reducing driver losses. |
| Automated Test Equipment (ATE) | Printed Circuit Board Assembly |
|
Use Scenario: Actuating precision linear stages in automated optical inspection systems where repeatability and thermal stability are critical. IC Role / Device Role / Timing Role: Motor driver operating under closed-loop feedback from encoder; uses PHASE/ENABLE to implement acceleration profiles. Use Value: Independent bridge enable allows dynamic current scaling per phase; 16-pin SOICW simplifies layout in space-constrained ATE modules. |
Use Scenario: Driving pick-and-place nozzle actuators in compact SMT placement machines requiring rapid, bidirectional movement. IC Role / Device Role / Timing Role: Bipolar stepper controller managing coil polarity reversal and current limiting via external sense resistors and VREF divider. Use Value: Satlington outputs deliver high peak current for fast acceleration without external boost circuitry; integrated diodes reduce BOM count. |
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 |
|---|---|---|---|
| TB6600HG | Higher peak current (4.0 A), but requires external flyback diodes and lacks integrated blanking window control. | Better suited for high-torque NEMA 23+ motors; less suitable for compact, low-noise designs where integrated protection is prioritized. | Select when higher current and external component flexibility outweigh integration benefits of A3966SA. |
| DRV8825 | Microstepping support (up to 1/32), integrated current DAC, but lower max supply voltage (45 V) and no Satlington architecture. | Preferred for high-resolution positioning; lacks the low-saturation sink performance and blanking configurability of A3966SA. | Choose for microstepping-centric applications where resolution trumps raw efficiency and transient immunity. |
Compared with TB6600HG and DRV8825, the A3966SA offers superior thermal efficiency via Satlington sinks, configurable blanking for robust transient immunity, and fully integrated protection - making it optimal for cost-sensitive, thermally constrained industrial stepper nodes where ±650 mA suffices.
Availability
A3966SA is available at Aetrix Electronics and suitable for industrial CNC positioning, medical infusion pumps, automated test equipment, and printed circuit board assembly requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for A3966SA 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 Hall-effect sensors, motor drivers, and power ICs, specializing in magnetic sensing and motion control solutions for automotive and industrial markets.
The A3966SA belongs to Allegro's legacy bipolar stepper driver product line, engineered for robust, integrated full-bridge control in cost-sensitive motion systems where reliability, thermal efficiency, and minimal external component count are essential.
FAQ
What is the maximum continuous output current per bridge of the A3966SA?
The A3966SA delivers ±650 mA continuous output current per full-bridge at TA ≤ 85 °C with adequate PCB copper area. Peak current capability reaches ±750 mA, but sustained operation above ±650 mA requires careful thermal management due to package power dissipation limits (1.87 W at 25 °C ambient).
How is PWM frequency configured on the A3966SA?
The A3966SA uses an external RC network connected to the RC pin to set its internal oscillator frequency. With RT = 56 kΩ and CT = 680 pF, the nominal frequency is 25.4 kHz. The blanking window duration is also derived from CT (tblank = 1900 × CT), ensuring synchronized noise immunity during switching transitions.
Does the A3966SA require external flyback diodes?
No, the A3966SA integrates internal ground-clamp and flyback diodes for each bridge output. This eliminates the need for external diodes in standard bipolar stepper configurations, reducing BOM count and PCB footprint while maintaining safe inductive energy recirculation during current decay.
What protection features are built into the A3966SA?
The A3966SA includes UVLO (4.1–4.6 V activation), thermal shutdown (165 °C typical with 15 °C hysteresis), crossover-current protection (1 µs dead time), and internal current-sense comparator blanking. These features collectively prevent damage from overvoltage, overtemperature, shoot-through, and false PWM triggering.
Can the A3966SA be used for microstepping applications?
The A3966SA does not natively support microstepping - it implements full-step and half-step control via PHASE/ENABLE logic. However, it can be paired with an external microstepping controller that generates appropriate PHASE and ENABLE waveforms, leveraging its precise current regulation and fast enable/disable response for accurate current profiling.
A3966SA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 16-DIP (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:
- 650mA
- Voltage - Supply:
- 4.75V ~ 5.5V
- Voltage - Load:
- 4.75V ~ 30V
- Operating Temperature:
- -20°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-DIP
A3966SA FAQ
1.How can I place an order for A3966SA through Aetrix?
Please submit a Request for Quotation (RFQ) for A3966SA 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 A3966SA reliable?
The price and inventory of A3966SA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3966SA is usually 5 days.
3.What payment methods are accepted for A3966SA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3966SA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3966SA?
A3966SA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3966SA 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 A3966SA?
For technical support, including A3966SA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3966SA requirements.
6.How does Aetrix verify that A3966SA is sourced from the original manufacturer or authorized distributors?
All A3966SA 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 A3966SA meets industry standards.
7.What is the process for return or replacement of A3966SA?
All A3966SA units undergo pre-shipment inspection (PSI). If there is an issue with A3966SA, 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 A3966SA part is unused and in its original packaging.
Return procedure for A3966SA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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