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Allegro MicroSystems A3972SB-T
- Part No.:
- A3972SB-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 24-PowerDIP (0.300", 7.62mm)
- Datasheet:
-
A3972SB-T.pdf
- Description:
- IC MTR DRV BIPOLR 4.5-5.5V 24DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,722
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Product details
Overview
A3972SB-T from Allegro MicroSystems is a dual DMOS full-bridge PWM motor driver designed for bipolar microstepping stepper motor control, delivering ±1.5 A continuous output current at up to 50 V supply voltage, with programmable mixed/fast/slow current-decay modes and two 6-bit linear DACs for precise torque control in industrial motion systems.
For engineers reviewing the A3972SB-T datasheet, A3972SB-T pinout, A3972SB-T application, or A3972SB-T equivalent, this device supports serial-interface configuration of PWM timing, synchronous rectification, thermal shutdown with hysteresis, and 4 MHz internal oscillator-based current regulation-key selection criteria for precision stepper drive designs.
Technical Context
The A3972SB-T integrates two independent H-bridge drivers with dedicated 6-bit DACs per bridge, enabling independent current control for dual-phase stepper motors. Its fixed off-time PWM architecture uses a programmable 4 MHz oscillator (internal or external) and supports blank-time, fast-decay time, and off-time configuration via 19-bit serial words.
Current regulation relies on VREF/RS scaling with selectable gain (×4 or ×8), where ITRIP = VDAC/(Range × RS). Synchronous rectification operates in four modes-active, passive, disabled, or low-side-only-controlled by two serial bits, directly reducing power dissipation by leveraging low RDS(on) DMOS outputs instead of external clamp diodes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | ±1.5 A continuous per bridge - supports NEMA 17–23 stepper motors without external heatsinking under typical ambient conditions. |
| Supply Voltage | Up to 50 V load supply - enables direct interface with 24 V and 48 V industrial DC bus systems. |
| DAC Resolution | 6-bit linear per bridge (64 steps) - provides 1.56% current increment granularity for smooth microstepping across full-, half-, quarter-, and 1/32-step modes. |
| RDS(on) | 0.315 Ω (sink), 0.5 Ω (source) - minimizes conduction loss and thermal rise during high-current PWM operation. |
| Oscillator | 4 MHz internal (±25% tolerance) or external clock input - sets PWM timing base; off-time adjustable from 1.75 μs to 63.75 μs in 2 μs increments. |
| Reference Voltage | 2.0 V internal (±30 mV accuracy) or external up to 3 V - defines current-sense threshold with total DAC error ≤ ±½ LSB. |
| Thermal Protection | Junction shutdown at 165°C with 15°C hysteresis - prevents latch-up during overload or poor heatsinking while allowing safe recovery. |
Pinout & Package
Package: 24-pin plastic DIP with two batwing power tabs (suffix 'B'); power tabs are at ground potential and require no electrical isolation. Pins 6, 7, 18, and 19 are internally fused per JEDEC MS-001 BE outline.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 20, 21, 22, 23, 24 | Logic I/O / Ground | Serial interface (CLOCK, DATA, STROBE), phase/mode control, sleep input, and ground returns - compatible with 3.3 V or 5 V logic levels. |
| 6, 7, 18, 19 | Fused Logic Pins | Internally fused connections - used for internal signal routing; not user-accessible for external connection. |
| 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 | Bridge Outputs & Sense | OUT1A/OUT1B/OUT2A/OUT2B (H-bridge outputs), SENSE1/SENSE2 (current sense inputs), VBB1/VBB2 (load supplies), VREG (regulated sink supply). |
| VCP, CP1, CP2 | Charge Pump | Supports gate drive for high-side DMOS transistors; requires 0.22 μF capacitor between CP1–CP2 and VCP–ground. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Rectification | Four configurable modes (active/passive/disabled/low-side-only) eliminate need for external Schottky diodes in most applications, cutting BOM count and power loss. |
| Programmable Decay Modes | Mixed, fast, or slow current decay per bridge - optimizes torque ripple and acoustic noise for specific motor inductance and step rate. |
| Serial Configuration Interface | 3-wire (CLOCK/DATA/STROBE), 19-bit word format - enables runtime reconfiguration of PWM timing, blank time, off-time, and decay behavior without hardware change. |
| Thermal & Electrical Protection | Integrated UVLO (4.2 V enable threshold), crossover-current protection, and thermal shutdown with hysteresis - ensures robust operation under fault conditions without external supervision. |
| Low-Power Modes | Idle mode (1.5 mA) and sleep mode (100 μA) - reduces system standby power while retaining serial register state or fully resetting logic. |
Applications
| Industrial CNC Positioning | Medical Infusion Pumps |
|---|---|
|
Use Scenario: Precision open-loop positioning of X/Y/Z axes in compact CNC mills using 1.8° bipolar stepper motors. IC Role / Device Role / Timing Role: Dual full-bridge driver executing microstepping commands via SPI-like serial interface; regulates phase current with 6-bit DACs and fixed-off-time PWM. Use Value: Enables 1/32-step resolution with <1.56% current step linearity, reducing motor vibration and improving surface finish without encoder feedback. |
Use Scenario: Controlled fluid delivery in portable infusion pumps requiring silent, repeatable peristaltic motion. IC Role / Device Role / Timing Role: Stepper driver managing bidirectional motor rotation and precise dwell timing; uses slow-decay mode to minimize audible coil whine. Use Value: Synchronous rectification cuts heat generation in sealed enclosures, extending battery life and eliminating need for external diodes in space-constrained PCB layouts. |
| Automated Laboratory Equipment | 3D Printer Extruder Control |
|
Use Scenario: Sample carousel indexing and pipette actuation in benchtop analyzers with strict EMI and thermal limits. IC Role / Device Role / Timing Role: Dual-bridge controller driving two independent stepper loads; configured via serial port for synchronized start/stop and current ramping. Use Value: Thermal shutdown with 15°C hysteresis prevents thermal runaway during extended duty cycles, ensuring uninterrupted assay runs. |
Use Scenario: High-speed filament feeding in FDM 3D printers where extruder motor must respond instantly to G-code acceleration profiles. IC Role / Device Role / Timing Role: PWM motor driver executing real-time current updates via serial strobe; uses mixed-decay mode to balance torque and heat during rapid direction changes. Use Value: 4 MHz oscillator + programmable blank time (4–12/fOSC) rejects switching noise during current sensing, preventing false overcurrent trips during acceleration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual H-bridge stepper driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TB6600HG | Higher 4.5 A rating but no integrated DACs; requires external current-sense resistors and analog control or step/direction interface. | Lacks serial programmability and microstepping flexibility; suited for simpler step/dir systems rather than closed-loop torque tuning. | Choose TB6600HG only when peak current >1.5 A is required and DAC-based current profiling is unnecessary. |
| DRV8825 | Integrated 1/32 microstepping, but single-channel; max 2.2 A with aggressive heatsinking; no dual-bridge integration or serial configuration. | Requires two ICs for dual-axis control; lacks independent bridge decay mode control and synchronous rectification configurability. | Select DRV8825 only for cost-sensitive single-axis designs where board area allows duplication and serial reconfiguration is not needed. |
Compared with TB6600HG and DRV8825, the A3972SB-T uniquely delivers dual independent bridges with serial-programmable 6-bit DACs, mixed/fast/slow decay per channel, and configurable synchronous rectification - enabling compact, thermally efficient, and acoustically optimized dual-axis stepper control without external components or duplicated ICs.
Availability
A3972SB-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, long-term lifecycle support, and traceable sourcing.
Supply support for A3972SB-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, energy-efficient power conversion, and automotive-grade reliability.
The A3972SB-T belongs to Allegro's stepper motor driver product line, engineered specifically for precision bipolar microstepping applications demanding programmable current control, thermal resilience, and minimal external component count in industrial and medical equipment.
FAQ
What is the maximum continuous output current supported by the A3972SB-T?
The A3972SB-T supports ±1.5 A continuous output current per bridge under standard operating conditions (TA = 25°C, adequate heatsinking). This rating assumes proper PCB layout with ground plane and decoupling, and may decrease with rising ambient temperature or reduced thermal mass. The absolute maximum junction temperature is 150°C, and thermal shutdown activates at 165°C to protect the device.
Does the A3972SB-T include an internal oscillator, and can it be overridden?
Yes, the A3972SB-T features a 4 MHz internal oscillator for PWM timing, with typical accuracy of ±25%. It can be overridden by connecting an external clock source to the OSC pin; the serial interface allows selection of internal clock, external clock, or divided versions (÷2 or ÷4) via D12–D13 bits. This flexibility supports systems requiring tighter frequency stability than the internal RC oscillator provides.
How does the A3972SB-T implement current regulation for microstepping?
The A3972SB-T uses two independent 6-bit linear DACs (one per bridge) to set reference voltage for current-limit comparators. With internal 2.0 V reference and selectable gain (×4 or ×8), ITRIP = VDAC/(Range × RS), where VDAC = [(1 + DAC code) × VREF]/64. This yields 64 discrete current levels at 1.56% increments, enabling precise torque control across full-step to 1/32-step microstepping modes.
What protection features are built into the A3972SB-T?
The A3972SB-T integrates thermal shutdown with 15°C hysteresis (trip at 165°C), undervoltage lockout (UVLO) on VDD (enable at 4.2 V), crossover-current protection, and transient-suppression diodes. It also includes blank-time programming to reject current-sense spikes during switching. No special power-up sequencing is required, and all protections operate autonomously without external circuitry.
Can the A3972SB-T drive two separate stepper motors simultaneously?
Yes, the A3972SB-T contains two fully independent DMOS H-bridges (Bridge 1 and Bridge 2), each with dedicated DACs, phase/mode control, and current-sense inputs. It is explicitly designed for dual-axis bipolar stepper motor control - for example, driving X/Y axes in CNC or left/right carousels in lab automation - with independent serial programming of current, decay mode, and direction per bridge.
A3972SB-T 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:
- Serial
- Technology:
- DMOS
- Step Resolution:
- 1 ~ 1/64
- Applications:
- General Purpose
- Current - Output:
- 1.5A
- Voltage - Supply:
- 4.5V ~ 5.5V
- Voltage - Load:
- 15V ~ 50V
- Operating Temperature:
- -20°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 24-DIP
A3972SB-T FAQ
1.How can I place an order for A3972SB-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A3972SB-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 A3972SB-T reliable?
The price and inventory of A3972SB-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3972SB-T is usually 5 days.
3.What payment methods are accepted for A3972SB-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3972SB-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3972SB-T?
A3972SB-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3972SB-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 A3972SB-T?
For technical support, including A3972SB-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3972SB-T requirements.
6.How does Aetrix verify that A3972SB-T is sourced from the original manufacturer or authorized distributors?
All A3972SB-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 A3972SB-T meets industry standards.
7.What is the process for return or replacement of A3972SB-T?
All A3972SB-T units undergo pre-shipment inspection (PSI). If there is an issue with A3972SB-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 A3972SB-T part is unused and in its original packaging.
Return procedure for A3972SB-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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