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Allegro MicroSystems A4973SB-T
- Part No.:
- A4973SB-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 16-PowerDIP (0.300", 7.62mm)
- Datasheet:
-
A4973SB-T.pdf
- Description:
- IC MTR DRVR BIPOLAR 3-5.5V 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,659
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Product details
Overview
A4973SB-T from Allegro MicroSystems is a discontinued 16-pin DIP full-bridge PWM motor driver IC designed for bidirectional current control of inductive loads such as brushed DC and stepper motors. It delivers ±1.5 A continuous output current, supports up to 50 V load supply voltage, and integrates fixed off-time PWM current regulation with user-configurable RC timing. It was used in motion control systems requiring fast/slow decay modes, brake functionality, and thermal protection.
For engineers reviewing the A4973SB-T datasheet, A4973SB-T pinout, A4973SB-T application, or A4973SB-T equivalent, this page provides verified technical context, validated pin functions, confirmed alternative parts for legacy design support, and precise specification mapping - all tied explicitly to the A4973SB-T DIP package and its documented electrical behavior.
Technical Context
The A4973SB-T implements an internal transconductance-based PWM current controller that compares sensed load current (via external RS and REF) against a user-set trip threshold ITRIP ≈ VREF/(2 × RS). Its fixed off-time tOFF ≈ RT × CT is externally programmable (e.g., 20.4 µs typical with 30 kΩ/680 pF), enabling ripple and EMI control.
It features dual decay modes selected by MODE input: slow decay (source disabled, both sinks active) and fast decay (both source and sink drivers switched). Brake operation overrides ENABLE/PHASE to force both sinks on, while sleep mode (ENABLE = HIGH + MODE = HIGH) reduces ICC to 250–450 µA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | ±1.5 A continuous - defines maximum sustained motor winding current without thermal derating under specified heatsinking |
| Load Supply Voltage | 5 V to 50 V - sets operational range for brushed DC or stepper motor power rails |
| Logic Supply Voltage | 3.0–5.5 V - compatible with standard 3.3 V or 5 V microcontroller I/O domains |
| PWM Fixed Off-Time | 18.3–22.5 µs (typ. 20.4 µs) - determines minimum current decay interval and regulates peak-to-peak ripple |
| Thermal Shutdown | 165°C (typ.) with 15°C hysteresis - protects die during overload or poor heatsinking; requires external tab cooling |
| UVLO Threshold | 2.75 V (min 2.5 V, max 3.0 V) - prevents erratic operation during logic supply brownout |
| Max PWM Frequency | 70 kHz - constrains minimum tOFF + tON(min) cycle time for high-speed commutation |
Pinout & Package
Package: 16-pin DIP (Package B) with exposed copper thermal tab at ground potential - requires no electrical isolation but mandates PCB copper area for thermal management (RθJA = 43°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 15, 16 | Ground | Common return for logic, sense, and power paths; connects directly to thermal tab |
| 3 | VCC | 3.0–5.5 V logic supply input - powers internal logic, comparators, and latch |
| 4 | PHASE | Digital input controlling current polarity: HIGH = forward, LOW = reverse |
| 5 | MODE | Selects decay mode: HIGH = fast decay, LOW = slow decay |
| 6 | REF | Analog reference input (0–1 V) setting peak current limit via ITRIP ≈ VREF/(2 × RS) |
| 7 | OUT A | High-side output driver terminal - connects to one motor winding end |
| 8 | OUT B | High-side output driver terminal - connects to opposite motor winding end |
| 9 | ENABLE | Active-low enable: LOW = functional, HIGH = all outputs disabled + sleep mode if MODE = HIGH |
| 10 | SENSE | Differential current sense input - monitors voltage across external RS resistor |
| 11 | BRAKE | Active-low brake override: forces both sinks ON regardless of PHASE/ENABLE state |
| 12, 13 | VBB | Motor supply input (5–50 V) - powers H-bridge output stage; decoupling capacitor required |
| 14 | RC | RC timing node - sets tOFF and comparator blanking window via external RT/CT |
Key Features
| Feature | Design Value |
|---|---|
| Integrated PWM current control | Eliminates need for external current-loop controller; enables closed-loop regulation using only REF, SENSE, and RC components |
| Fast/slow current decay selection | Reduces switching losses in slow mode (ideal for stepper hold) and improves current settling in fast mode (for dynamic braking) |
| Brake function with priority override | Ensures immediate motor stop by forcing both low-side switches ON - independent of PHASE/ENABLE state |
| Internal transient suppression diodes | Clamps inductive kickback without external flyback diodes - simplifies layout and reduces BOM count |
| Thermal shutdown with hysteresis | Prevents thermal runaway during overload; 15°C hysteresis avoids oscillation near trip point |
Applications
| Brushed DC Motor Control | Stepper Motor Microstepping |
|---|---|
|
Use Scenario: Bidirectional speed and torque control of 12–48 V brushed DC motors in industrial actuators or robotic joints. IC Role / Device Role / Timing Role: Full-bridge driver executing PHASE/PWM-controlled current direction and magnitude; uses slow decay for efficient holding torque. Use Value: Enables linear transfer function between PHASE duty cycle and motor voltage - critical for servo positioning accuracy at low speeds. |
Use Scenario: Precision current profiling in bipolar stepper drivers for CNC stages or 3D printer axes. IC Role / Device Role / Timing Role: Dual-channel current regulator applying sinusoidal or microstepped waveforms via synchronized REF modulation and MODE-switched decay. Use Value: Slow decay during current rise minimizes switching loss; fast decay during fall prevents tailing - preserving step resolution and reducing audible noise. |
| Dynamic Braking Systems | Industrial Motion Controllers |
|
Use Scenario: Emergency stopping of rotating machinery where kinetic energy must be dissipated rapidly. IC Role / Device Role / Timing Role: Brake input asserts independent of control logic to short motor windings through low-RDS(on) sinks. Use Value: Achieves sub-millisecond brake response; limits peak braking current via internal UVLO and thermal shutdown - avoiding device failure. |
Use Scenario: Modular motion control modules requiring robust, field-serviceable motor drivers with fault reporting. IC Role / Device Role / Timing Role: Core power stage with integrated protection (TSD, UVLO, crossover prevention) and diagnostic-ready pins (SENSE, RC). Use Value: Reduces system-level fault detection complexity - thermal and supply faults trigger automatic shutdown without host intervention. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar full-bridge PWM motor driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| A4973SLBTR-T | Same electrical specifications and pinout; SOICW package (LB) with fused pins and RθJA = 67°C/W | Requires PCB redesign for SOIC footprint; better suited for automated assembly and higher-density layouts | Direct replacement for new designs - Allegro's designated successor with identical functionality |
| TB6612FNG | Lower voltage rating (15 V), lower current (1.2 A), no internal RC timing - requires external oscillator | Limited to low-voltage robotics; lacks brake priority override and thermal hysteresis | Acceptable only for cost-sensitive, low-power applications where 50 V/±1.5 A capability is unnecessary |
Compared with A4973SB-T, A4973SLBTR-T maintains full electrical and functional equivalence in a surface-mount package, while TB6612FNG trades voltage/current headroom and integrated protection for smaller size and lower cost - making it suitable only for non-critical, low-power replacements.
Availability
A4973SB-T is available at Aetrix Electronics and suitable for legacy repair, obsolescence mitigation, and industrial maintenance programs requiring stable component supply for discontinued motion control systems.
Supply support for A4973SB-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 A4973 product line was engineered for robust, thermally resilient full-bridge motor control in factory automation and precision motion systems - emphasizing integrated protection, flexible decay modes, and analog current regulation.
FAQ
Is A4973SB-T still recommended for new designs?
No. A4973SB-T is obsolete per Allegro's July 2018 status change. New designs must use A4973SLBTR-T, which shares identical electrical behavior and pinout in an SOICW package. A4973SB-T remains available only for legacy repair and obsolescence management - not for prototyping or production ramp.
What is the maximum allowable voltage on the SENSE pin of A4973SB-T?
The absolute maximum voltage on the SENSE pin of A4973SB-T is 500 mV. Exceeding this risks comparator saturation and inaccurate current limiting. The device's internal current-sense amplifier operates down to ground, supporting microstepping and sinusoidal current profiles when paired with low-value sense resistors.
How does the RC timing network affect A4973SB-T performance?
The RC network on the A4973SB-T's RC pin sets both the fixed off-time (tOFF ≈ RT × CT) and the comparator blanking window. Increasing tOFF reduces switching losses and EMI but increases ripple current and lowers max PWM frequency - typical values range 15–35 µs to balance acoustic noise and regulation fidelity.
Can A4973SB-T operate with a 3.3 V logic supply?
Yes. A4973SB-T supports 3.0–5.5 V logic supply (VCC), including 3.3 V operation. At 3.3 V, the minimum recommended CT is 680 pF ±5% to ensure sufficient blanking time and prevent false overcurrent trips during switching transients.
What thermal management is required for A4973SB-T in continuous operation?
A4973SB-T requires connection of its exposed thermal tab to ≥6 cm² of 2-oz copper on the PCB to achieve RθJA = 43°C/W. Junction temperature must stay below 125°C for reliable operation; TJ ≈ TTAB + ILOAD² × RDS(on) × 6°C/W, where RDS(on) = 1.0–1.4 Ω total (source + sink).
A4973SB-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 16-PowerDIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Motor Type - Stepper:
- Bipolar
- Motor Type - AC, DC:
- Brushed DC
- Function:
- Driver - Fully Integrated, Control and Power Stage
- Output Configuration:
- Half Bridge (2)
- Interface:
- Parallel
- Technology:
- Power MOSFET
- Step Resolution:
- -
- Applications:
- General Purpose
- Current - Output:
- 1.5A
- Voltage - Supply:
- 3V ~ 5.5V
- Voltage - Load:
- 5V ~ 50V
- Operating Temperature:
- -20°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-DIP
A4973SB-T FAQ
1.How can I place an order for A4973SB-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A4973SB-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 A4973SB-T reliable?
The price and inventory of A4973SB-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A4973SB-T is usually 5 days.
3.What payment methods are accepted for A4973SB-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A4973SB-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A4973SB-T?
A4973SB-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A4973SB-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 A4973SB-T?
For technical support, including A4973SB-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A4973SB-T requirements.
6.How does Aetrix verify that A4973SB-T is sourced from the original manufacturer or authorized distributors?
All A4973SB-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 A4973SB-T meets industry standards.
7.What is the process for return or replacement of A4973SB-T?
All A4973SB-T units undergo pre-shipment inspection (PSI). If there is an issue with A4973SB-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 A4973SB-T part is unused and in its original packaging.
Return procedure for A4973SB-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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