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Allegro MicroSystems A3949SLB-T
- Part No.:
- A3949SLB-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 16-PowerSOIC (0.295", 7.50mm Width)
- Datasheet:
-
A3949SLB-T.pdf
- Description:
- IC MOTOR DRIVER 8V-36V 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,336
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Product details
Overview
A3949SLB-T from Allegro MicroSystems is a discontinued DMOS full-bridge motor driver IC designed for PWM-controlled bidirectional DC motor operation, delivering ±2.8 A peak output current at up to 36 V supply voltage, with PHASE/ENABLE control interface and integrated synchronous rectification for reduced power loss in industrial actuators and automotive seat/mirror systems.
For engineers reviewing the A3949SLB-T datasheet, A3949SLB-T pinout, A3949SLB-T application, or A3949SLB-T equivalent, key selection considerations include its 16-pin SOIC LB package with fused pins 4 (SLEEP) and 13 (VCP), thermal shutdown at 170°C, UVLO threshold of 6 V, sleep-mode quiescent current ≤10 μA, and RDS(ON) as low as 0.3 Ω (sink) at 25°C.
Technical Context
The A3949SLB-T implements a four-switch DMOS H-bridge with independent source/sink gate drive architecture, using an internal charge pump (CP1/CP2) to generate VCP > VBB for high-side NMOS control and a dedicated VREG regulator for low-side gate bias. It supports forward/reverse/brake/fast-decay SR modes via MODE, PHASE, and ENABLE logic inputs.
Protection is implemented through three independent monitoring circuits: VBB/VCP undervoltage lockout with 250 mV hysteresis, thermal shutdown at 170°C with 15°C hysteresis, and crossover current protection with 500 ns delay. Sleep mode disables charge pump and VREG, reducing supply current to ≤10 μA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Output Current | ±2.8 A - supports medium-power DC motors up to ~100 W at 36 V with appropriate heatsinking |
| Supply Voltage Range | 8–36 V - compatible with 12 V and 24 V industrial and automotive battery systems |
| RDS(ON) (Sink, 25°C) | 0.3 Ω typ - limits conduction loss to <1.2 W per switch at 2 A continuous |
| UVLO Threshold | 6 V rising - prevents erratic operation during brown-out or cold-cranking conditions |
| Thermal Shutdown | 170°C junction - protects against latch-up during overload or poor PCB thermal design |
| Sleep Current | ≤10 μA - enables ultra-low-power standby in battery-operated portable devices |
| Propagation Delay | 100–600 ns - ensures precise PWM timing alignment for motor current regulation |
Pinout & Package
The A3949SLB-T is housed in a 16-pin SOIC Wide (LB) package with internally fused pins 4 (SLEEP) and 13 (VCP), copper batwing thermal tab, Pb-free construction, and 100% matte tin leadframes. Package outline conforms to JEDEC MS-013 AA.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 15 | N/C | No internal connection; must be left unconnected or tied to GND per layout guidelines |
| 2 | MODE | Selects decay mode (slow/fast) and braking behavior; critical for EMI and current ripple control |
| 3, 12 | GND | Power ground return path for motor current and internal logic; requires low-impedance PCB plane |
| 4 | SLEEP | Active-high logic input; enables ultra-low-power state by disabling charge pump and VREG |
| 5 | ENABLE | Global PWM enable/disable; forces Hi-Z outputs when low, overriding PHASE/MODE states |
| 6, 9 | OUTA / OUTB | H-bridge output terminals; connect directly to motor leads; require external flyback diodes if not using SR |
| 7 | SENSE | Current-sense return node; used with external sense resistor for overcurrent detection |
| 8 | VBB | Main motor supply input; must be decoupled with ≥100 μF electrolytic + 0.1 μF ceramic |
| 10, 11 | CP1 / CP2 | Charge pump oscillator nodes; require 0.1 μF ceramic capacitor between them for gate drive boost |
| 13 | VCP | Charge pump reservoir; monitored for UVLO; requires 0.1 μF ceramic to VBB |
| 14 | VREG | Low-side gate regulator output; requires 0.22 μF ceramic decoupling to GND |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Rectification | Reduces conduction losses by enabling body diode bypass during PWM off-time, improving efficiency by ~15% vs. freewheeling diodes |
| Integrated Charge Pump | Eliminates need for external high-voltage gate driver; supports 100% duty cycle operation without bootstrap capacitor limitations |
| Fused SLEEP and VCP Pins | Pins 4 and 13 are internally connected to simplify PCB routing and reduce risk of misconnection in high-vibration environments |
| Thermal Hysteresis | 15°C shutdown hysteresis prevents oscillation near trip point, ensuring stable recovery after overload events |
| UVLO with Dual Monitoring | Independent VBB and VCP undervoltage detection prevents shoot-through and gate drive failure during supply transients |
Applications
| Automotive Power Seats | Industrial Linear Actuators |
|---|---|
Use Scenario: Bidirectional adjustment of vehicle seat position under varying mechanical load and temperature. IC Role / Device Role / Timing Role: Full-bridge motor driver executing PHASE/ENABLE PWM commands from MCU to control direction and speed. Use Value: ±2.8 A peak current and 36 V rating support high-torque seat motors; thermal shutdown protects against jammed mechanisms. | Use Scenario: Precision positioning of valves, dampers, or robotic joints in factory automation equipment. IC Role / Device Role / Timing Role: Motor interface translating microcontroller PWM signals into controlled H-bridge switching with synchronous rectification. Use Value: Low RDS(ON) (0.3 Ω sink) minimizes heat generation during continuous duty cycles; sleep mode reduces standby power in idle states. |
| Medical Bed Adjusters | Consumer Robotics Mobility |
Use Scenario: Smooth, quiet height and tilt adjustment of hospital beds with safety-critical fault response. IC Role / Device Role / Timing Role: Fault-monitored motor driver providing forward/reverse/brake functions with UVLO and thermal shutdown. Use Value: Crossover current protection and 500 ns delay prevent shoot-through; 170°C shutdown ensures safe thermal margin in enclosed enclosures. | Use Scenario: Differential drive for wheeled robots requiring responsive direction reversal and regenerative braking. IC Role / Device Role / Timing Role: H-bridge controller implementing fast-decay synchronous rectification via MODE/ENABLE logic for rapid current reversal. Use Value: Fast-decay SR mode enables efficient BEMF shorting during braking; propagation delays <600 ns ensure tight current loop control. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar full-bridge motor driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| A3950SLPTR-T | Successor device with improved thermal performance (RθJA = 42°C/W vs. 52°C/W), higher peak current (±3.5 A), and enhanced ESD rating (±4 kV HBM) | Supports higher ambient temperatures and denser PCB layouts; suitable for new designs where A3949SLB-T is obsolete | Select A3950SLPTR-T for new designs requiring extended lifetime support and higher power density |
| TB6612FNG | 2-channel H-bridge with lower voltage rating (15 V max), no internal charge pump, and separate VCC/Vmotor supplies | Better suited for low-voltage robotics (3.3–12 V); lacks integrated VCP/VREG monitoring and thermal hysteresis | Choose TB6612FNG only for cost-sensitive, low-power applications where 36 V operation and robust fault protection are not required |
Compared with A3949SLB-T, the A3950SLPTR-T offers higher current capability and better thermal resistance for sustained loads, while the TB6612FNG trades integration and voltage range for lower system cost and simpler supply architecture in sub-15 V designs.
Availability
A3949SLB-T is available at Aetrix Electronics and suitable for legacy repair, obsolescence mitigation, and maintenance of existing industrial motion control, automotive seat modules, and medical actuator systems requiring stable component supply despite end-of-life status.
Supply support for A3949SLB-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 sensing and power IC solutions, headquartered in Worcester, Massachusetts.
The A3949SLB-T belongs to Allegro's DMOS full-bridge motor driver product line, engineered for robust, integrated control of brushed DC motors in automotive and industrial environments where reliability under voltage transients and thermal stress is critical.
FAQ
Is the A3949SLB-T still in production?
No, the A3949SLB-T is a discontinued product. Allegro MicroSystems ceased production on June 2, 2014. It is not recommended for new designs, and samples are no longer available. Aetrix Electronics maintains limited legacy stock for repair and maintenance of existing systems.
What is the function of the fused pins 4 and 13 on the A3949SLB-T?
Pins 4 (SLEEP) and 13 (VCP) are internally fused in the A3949SLB-T LB package. This eliminates the need for external trace routing between them, reducing PCB complexity and improving reliability in high-vibration applications such as automotive seats and industrial actuators.
Can the A3949SLB-T operate without external capacitors on CP1, CP2, and VCP?
No. The A3949SLB-T requires a 0.1 μF ceramic capacitor between CP1 and CP2, and another 0.1 μF ceramic capacitor from VCP to VBB. Omitting these capacitors prevents proper charge pump operation, resulting in failed high-side gate drive and immediate device malfunction.
What protection features does the A3949SLB-T include?
The A3949SLB-T integrates thermal shutdown (170°C with 15°C hysteresis), VBB/VCP undervoltage lockout (6 V threshold, 250 mV hysteresis), and crossover current protection (500 ns delay). These features collectively prevent shoot-through, overheating, and supply collapse during fault conditions.
How does synchronous rectification work in the A3949SLB-T?
In the A3949SLB-T, synchronous rectification actively turns on the low-side MOSFET during the off-time of the high-side switch, replacing body-diode conduction. This reduces voltage drop from ~1.1 V to <0.4 V, cutting power loss and heat generation-especially beneficial in high-duty-cycle motor control applications.
A3949SLB-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 16-PowerSOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Motor Type - Stepper:
- -
- Motor Type - AC, DC:
- Brushed DC
- Function:
- Driver - Fully Integrated, Control and Power Stage
- Output Configuration:
- Half Bridge (2)
- Interface:
- Parallel
- Technology:
- DMOS
- Step Resolution:
- -
- Applications:
- General Purpose
- Current - Output:
- 2.8A
- Voltage - Supply:
- 8V ~ 36V
- Voltage - Load:
- 8V ~ 36V
- Operating Temperature:
- -20°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
A3949SLB-T FAQ
1.How can I place an order for A3949SLB-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A3949SLB-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 A3949SLB-T reliable?
The price and inventory of A3949SLB-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3949SLB-T is usually 5 days.
3.What payment methods are accepted for A3949SLB-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3949SLB-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3949SLB-T?
A3949SLB-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3949SLB-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 A3949SLB-T?
For technical support, including A3949SLB-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3949SLB-T requirements.
6.How does Aetrix verify that A3949SLB-T is sourced from the original manufacturer or authorized distributors?
All A3949SLB-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 A3949SLB-T meets industry standards.
7.What is the process for return or replacement of A3949SLB-T?
All A3949SLB-T units undergo pre-shipment inspection (PSI). If there is an issue with A3949SLB-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 A3949SLB-T part is unused and in its original packaging.
Return procedure for A3949SLB-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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