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Allegro MicroSystems A3949SLBTR
- Part No.:
- A3949SLBTR
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 16-PowerSOIC (0.295", 7.50mm Width)
- Datasheet:
-
A3949SLBTR.pdf
- Description:
- IC MOTOR DRIVER 8V-36V 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,952
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Product details
Overview
A3949SLBTR from Allegro MicroSystems is a DMOS full-bridge motor driver IC designed for PWM-controlled DC motors, delivering ±2.8 A peak output current at up to 36 V supply voltage, with PHASE/ENABLE control interface and internal synchronous rectification for reduced power loss in industrial actuators and automotive seat/mirror systems.
For engineers reviewing the A3949SLBTR datasheet, A3949SLBTR pinout, A3949SLBTR application, or A3949SLBTR equivalent, key selection criteria include thermal shutdown (170°C), UVLO threshold (6 V), sleep-mode quiescent current (10 µA), RDS(ON) (0.3–0.68 Ω), and LB-package thermal resistance (52 °C/W).
Technical Context
The A3949SLBTR implements a four-switch DMOS H-bridge with independent source/sink gate drive architecture, charge-pump-based high-side gate supply (VCP), and low-side gate regulator (VREG). It supports forward/reverse/brake/fast-decay SR modes via MODE, PHASE, ENABLE, and SLEEP logic inputs.
Internal protection includes crossover current detection (500 ns delay), undervoltage lockout on VBB and VCP (6 V ±250 mV), and thermal shutdown with 15°C hysteresis. The device requires external 0.1 µF CP1–CP2 and VCP–VBB capacitors plus 0.22 µF VREG decoupling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Output Current | ±2.8 A - supports medium-power DC motors without external current sensing |
| Supply Voltage Range | 8–36 V - compatible with 12 V and 24 V industrial and automotive battery rails |
| RDS(ON) (Sink, 25°C) | 0.3 Ω typ - limits conduction loss to ≤2.35 W per switch at 2.8 A |
| RDS(ON) (Source, 25°C) | 0.4 Ω typ - enables efficient high-side switching without bootstrap diode |
| Thermal Shutdown Temp | 170°C - triggers automatic output disable before junction damage occurs |
| Sleep Mode Current | 10 µA max - reduces system standby power in battery-powered applications |
| UVLO Threshold | 6 V rising - prevents erratic operation during brown-out or cold-cranking conditions |
Pinout & Package
The A3949SLBTR is supplied in a 16-pin SOICW package with copper batwing tab (suffix LB), lead-free construction, and internally fused pins 4 (SLEEP) and 13 (VCP). Thermal pad is not electrically connected but enhances heatsinking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 15 | N/C | No internal connection; must be left unconnected |
| 2 | MODE | Selects slow/fast decay braking mode; determines SR behavior during current zero-crossing |
| 3, 12 | GND | Power ground return for load and logic; connects to thermal tab |
| 4 | SLEEP | Active-high enable for ultra-low-power state; disables charge pump and VREG |
| 5 | ENABLE | Global PWM gate; high = active output, low = Hi-Z outputs |
| 6, 9 | OUTA / OUTB | H-bridge output terminals; connect directly to motor terminals |
| 7 | SENSE | Current-sense return path; used with external sense resistor for overcurrent detection |
| 8 | VBB | Main motor supply input; rated 36 V absolute max (38 V transient) |
| 10, 11 | CP1 / CP2 | Charge pump oscillator nodes; require 0.1 µF ceramic capacitor between them |
| 13 | VCP | High-side gate reservoir; monitored for UVLO; requires 0.1 µF cap to VBB |
| 14 | VREG | Low-side gate regulator output; requires 0.22 µF decoupling to GND |
| 16 | PHASE | Direction control input; sets OUTA/OUTB polarity when ENABLE is high |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Rectification | Reduces power dissipation during PWM off-time by enabling body diode bypass with active FET conduction |
| Integrated Charge Pump | Eliminates need for external bootstrap circuitry while supporting 100% duty cycle operation |
| Thermal Shutdown with Hysteresis | Prevents thermal runaway by disabling outputs at 170°C and re-enabling only after cooling ≥15°C |
| UVLO Monitoring on VBB & VCP | Ensures stable gate drive and prevents shoot-through during supply ramp-up or sag |
| Fast Decay SR Control | Enables controlled current recirculation during braking without reversal, improving torque response |
Applications
| Automotive Seat Actuators | Industrial Linear Actuators |
|---|---|
Use Scenario: Bidirectional positioning of powered vehicle seats using 12 V DC motors under varying load and temperature. IC Role / Device Role / Timing Role: Full-bridge driver executing PHASE/ENABLE PWM commands with integrated protection against battery sag and thermal overload. Use Value: Enables compact, robust motor control without external current sense or gate drivers-reducing BOM count by ≥3 components. | Use Scenario: Precision extension/retraction of factory automation linear stages driven by 24 V brushed DC motors. IC Role / Device Role / Timing Role: Motor interface translating PLC-generated PWM signals into bidirectional torque with fast-decay braking for rapid stop accuracy. Use Value: Delivers ±2.8 A peak current with <600 ns propagation delay, ensuring sub-millisecond motion response in closed-loop systems. |
| Medical Bed Positioning | Smart Home Window Blinds |
Use Scenario: Quiet, reliable height and tilt adjustment of hospital beds using low-inertia DC motors in safety-critical environments. IC Role / Device Role / Timing Role: Safety-aware motor controller with thermal shutdown, UVLO, and sleep mode to meet IEC 60601 leakage and power requirements. Use Value: Sleep current ≤10 µA extends battery backup runtime; internal protection eliminates need for external fault monitoring circuitry. | Use Scenario: Battery-powered motorized window coverings requiring multi-year operation on AA cells with remote PWM control. IC Role / Device Role / Timing Role: Energy-optimized bridge driver managing direction and speed via low-duty-cycle RF-received signals. Use Value: Integrated sleep mode and 10 µA quiescent current extend typical battery life from 6 to >24 months in intermittent-use deployments. |
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 | Same pinout, identical electrical specs, but in 16-pin TSSOP (LP) package with exposed thermal pad | Better thermal performance (RθJA = 40 °C/W vs. 52 °C/W); requires different PCB land pattern | Preferred for higher ambient temperature or continuous-current applications where board space allows LP footprint |
| TB6612FNG | Lower peak current (±1.2 A), no internal charge pump (requires external bootstrap), different pin assignment | Limited to lighter loads; lacks VCP/VREG monitoring and crossover protection | Suitable for cost-sensitive, low-power consumer devices where full A3949SLBTR protection set is not required |
Compared with A3949SLBTR, A3950SLPTR-T offers superior thermal management in the same functional form factor, while TB6612FNG provides a lower-cost, lower-performance alternative lacking critical protections and high-current capability.
Availability
A3949SLBTR is available at Aetrix Electronics and suitable for automotive seat actuators, industrial linear actuators, medical bed positioning, and smart home window blinds requiring stable component supply despite end-of-life status.
Supply support for A3949SLBTR 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, headquartered in Worcester, Massachusetts.
The A3949 belongs to Allegro's DMOS full-bridge motor driver product line, engineered specifically for robust, integrated control of brushed DC motors in automotive, industrial, and medical motion systems.
FAQ
Is A3949SLBTR still in production?
No, the A3949SLBTR is a discontinued product per Allegro's June 2014 status update. It is no longer manufactured, and samples are unavailable. Aetrix Electronics maintains limited legacy stock for design continuity and repair programs, subject to availability verification prior to order placement.
What is the recommended replacement for A3949SLBTR?
The A3950SLPTR-T is Allegro's officially recommended substitution, sharing identical electrical specifications and logic interface with the A3949SLBTR but packaged in a thermally enhanced 16-pin TSSOP (LP) format. Designers should verify PCB layout compatibility due to differing thermal pad and pin pitch requirements before migration.
Does A3949SLBTR support 100% duty cycle operation?
Yes, the A3949SLBTR supports 100% duty cycle operation due to its integrated charge pump architecture, which generates a gate drive voltage above VBB for the high-side DMOS switches. This eliminates reliance on bootstrap capacitors that fail at extended on-times, making it suitable for holding torque applications like brake engagement or static position maintenance.
What external components are mandatory for A3949SLBTR operation?
Mandatory external components for A3949SLBTR include: a 0.1 µF ceramic capacitor between CP1 and CP2; a 0.1 µF ceramic capacitor between VCP and VBB; a 0.22 µF ceramic capacitor from VREG to GND; and a current-sense resistor connected between SENSE and GND if overcurrent protection is implemented. No bootstrap diode or external gate drivers are required.
How does the sleep mode function in A3949SLBTR?
In A3949SLBTR, asserting a logic low on the SLEEP pin disables the charge pump, VREG regulator, and internal logic biasing, reducing total supply current to ≤10 µA. After waking (SLEEP = high), a 1 ms stabilization delay is required before applying PWM signals to allow VCP and VREG to reach regulation-ensuring reliable gate drive at startup.
A3949SLBTR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 16-PowerSOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- 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
A3949SLBTR FAQ
1.How can I place an order for A3949SLBTR through Aetrix?
Please submit a Request for Quotation (RFQ) for A3949SLBTR 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 A3949SLBTR reliable?
The price and inventory of A3949SLBTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3949SLBTR is usually 5 days.
3.What payment methods are accepted for A3949SLBTR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3949SLBTR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3949SLBTR?
A3949SLBTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3949SLBTR 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 A3949SLBTR?
For technical support, including A3949SLBTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3949SLBTR requirements.
6.How does Aetrix verify that A3949SLBTR is sourced from the original manufacturer or authorized distributors?
All A3949SLBTR 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 A3949SLBTR meets industry standards.
7.What is the process for return or replacement of A3949SLBTR?
All A3949SLBTR units undergo pre-shipment inspection (PSI). If there is an issue with A3949SLBTR, 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 A3949SLBTR part is unused and in its original packaging.
Return procedure for A3949SLBTR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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