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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Motor Drivers, Controllers

Allegro MicroSystems A3949SLPTR-T

Name: A3949SLPTR-T
Brand: Allegro MicroSystems
SKU: A3949SLPTR-T
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: A3949SLPTR-T

Manufacturer:: Allegro MicroSystems

Category:: Motor Drivers, Controllers

Package:: 16-TSSOP (0.173", 4.40mm Width) Exposed Pad

Datasheet:: A3949SLPTR-T.pdf

Description:: IC MOTOR DRIVER 8V-36V 16TSSOP

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Product details

Overview

A3949SLPTR-T 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 A3949SLPTR-T datasheet, A3949SLPTR-T pinout, A3949SLPTR-T application, or A3949SLPTR-T equivalent, key selection criteria include thermal shutdown (170°C), UVLO (6 V with 250 mV hysteresis), low R_DS(ON) (0.3–0.48 Ω), sleep mode current (≤10 μA), and LB-package SOIC-16 copper batwing thermal performance.

Technical Context

The A3949SLPTR-T implements a four-MOSFET full-bridge topology with independent source/sink drivers, charge pump (CP1/CP2) for high-side gate drive, and VREG-regulated low-side gate supply. It supports forward/reverse/brake/fast-decay SR modes via MODE, PHASE, ENABLE, and SLEEP logic inputs.

Protection architecture includes crossover current detection, thermal shutdown with 15°C hysteresis, and dual undervoltage lockout monitoring on both VBB (6 V threshold) and VCP (reservoir capacitor voltage), ensuring safe operation under brownout or charge-pump failure conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
Peak Output Current	±2.8 A - supports medium-power DC motors without external heatsinking in 2-layer PCB layouts
Supply Voltage Range	8–36 V - compatible with 12 V and 24 V industrial and automotive battery rails
R_DS(ON) (Sink/Source)	0.3–0.48 Ω @ 25°C - limits conduction loss to ≤2.4 W per channel at 2.8 A
UVLO Threshold	6 V with 250 mV hysteresis - prevents erratic switching during startup or battery sag
Thermal Shutdown	170°C junction temperature with 15°C hysteresis - enables automatic recovery after cooling
Sleep Mode Current	≤10 μA - reduces system standby power in battery-powered portable devices
Propagation Delay	100–600 ns - ensures precise PWM timing alignment for closed-loop motor control

Pinout & Package

The A3949SLPTR-T is housed in a 16-pin SOICW package (suffix LB) with exposed copper batwing thermal tab, lead-free construction, and internally fused pins 4 (SLEEP) and 13 (VCP).

Pin/Terminal	Circuit Role	Design Meaning
1, 15	N/C	No internal connection; must be left unconnected
2	MODE	Selects decay mode (slow/fast) and braking behavior via logic level
3, 12	GND	Power ground return paths; both pins required for low-impedance layout
4	SLEEP	Active-high input enabling ultra-low-power sleep state (≤10 μA I_BB)
5	ENABLE	Global PWM enable/disable; drives outputs to Hi-Z when low
6, 9	OUTA / OUTB	Full-bridge output terminals; connect directly to motor terminals
7	SENSE	Current-sense return path; used with external sense resistor for overcurrent protection
8	VBB	Main motor supply input (8–36 V); requires ≥100 μF bulk capacitance
10, 11	CP1 / CP2	Charge pump oscillator nodes; require 0.1 μF ceramic capacitors for high-side gate drive
13	VCP	Charge pump reservoir node; monitored for UVLO; decouple with 0.1 μF to VBB
14	VREG	Internally regulated low-side gate supply; decouple with 0.22 μF to GND

Key Features

Feature	Design Value
Synchronous Rectification	Reduces power dissipation during PWM off-time by actively turning on low-side FETs instead of relying on body diodes
Internal Charge Pump	Generates gate drive voltage >VBB for high-side DMOS switches, eliminating need for external bootstrap circuitry
Crossover Current Protection	Detects shoot-through risk during switching transitions and forces dead time to prevent simultaneous high-/low-side conduction
Thermal Shutdown with Hysteresis	Shuts down at 170°C and re-enables only after cooling by ≥15°C, preventing thermal oscillation in marginally heatsunk designs
Logic-Compatible Inputs	PHASE/ENABLE/MODE/SLEEP accept standard 3.3 V or 5 V CMOS/TTL levels without external level-shifting

Applications

Automotive Power Seats	Industrial Linear Actuators
Use Scenario: Bidirectional positioning of vehicle seat fore/aft and recline mechanisms using 12 V DC motors. IC Role / Device Role / Timing Role: Full-bridge driver executing PHASE/ENABLE-based direction and speed control with fast-decay SR for smooth stop response. Use Value: Enables compact ECU design with integrated protection (UVLO, thermal shutdown) and <10 μA sleep current for ignition-off power budget compliance.	Use Scenario: Precision extension/retraction of factory automation linear slides driven by 24 V brushed DC motors. IC Role / Device Role / Timing Role: Motor interface translating PLC PWM commands into bidirectional torque delivery with synchronous rectification for efficiency. Use Value: Delivers ±2.8 A peak current with 0.3 Ω sink R_DS(ON), reducing heat generation and enabling convection-cooled enclosure designs.
Medical Infusion Pumps	Consumer Robotics Platforms
Use Scenario: Controlled syringe advancement in battery-powered portable infusion devices requiring silent, low-ripple motion. IC Role / Device Role / Timing Role: Low-noise PWM motor controller implementing slow-decay braking to minimize mechanical vibration and audible coil whine. Use Value: Sleep mode (≤10 μA) extends single-charge battery life; internal UVLO prevents motor stall during low-battery conditions.	Use Scenario: Drive wheels and articulated joints in educational and hobbyist robots powered by 2-cell Li-ion (7.4 V) or 6-cell NiMH (8.4 V) packs. IC Role / Device Role / Timing Role: Compact full-bridge interface between microcontroller GPIOs and brushed DC gearmotors, supporting forward/reverse/brake states. Use Value: SOIC-16 LB package provides robust thermal performance without heatsinks; pin-compatible control logic simplifies firmware reuse across platforms.

Automotive Power Seats

Industrial Linear Actuators

Use Scenario: Bidirectional positioning of vehicle seat fore/aft and recline mechanisms using 12 V DC motors.

IC Role / Device Role / Timing Role: Full-bridge driver executing PHASE/ENABLE-based direction and speed control with fast-decay SR for smooth stop response.

Use Value: Enables compact ECU design with integrated protection (UVLO, thermal shutdown) and <10 μA sleep current for ignition-off power budget compliance.

Use Scenario: Precision extension/retraction of factory automation linear slides driven by 24 V brushed DC motors.

IC Role / Device Role / Timing Role: Motor interface translating PLC PWM commands into bidirectional torque delivery with synchronous rectification for efficiency.

Use Value: Delivers ±2.8 A peak current with 0.3 Ω sink R_DS(ON), reducing heat generation and enabling convection-cooled enclosure designs.

Medical Infusion Pumps

Consumer Robotics Platforms

Use Scenario: Controlled syringe advancement in battery-powered portable infusion devices requiring silent, low-ripple motion.

IC Role / Device Role / Timing Role: Low-noise PWM motor controller implementing slow-decay braking to minimize mechanical vibration and audible coil whine.

Use Value: Sleep mode (≤10 μA) extends single-charge battery life; internal UVLO prevents motor stall during low-battery conditions.

Use Scenario: Drive wheels and articulated joints in educational and hobbyist robots powered by 2-cell Li-ion (7.4 V) or 6-cell NiMH (8.4 V) packs.

IC Role / Device Role / Timing Role: Compact full-bridge interface between microcontroller GPIOs and brushed DC gearmotors, supporting forward/reverse/brake states.

Use Value: SOIC-16 LB package provides robust thermal performance without heatsinks; pin-compatible control logic simplifies firmware reuse across platforms.

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	Higher R_DS(ON) (0.55 Ω typ.), same 16-pin LB package, identical pinout and control logic	Lower efficiency at high current; suitable where thermal margin exists but cost sensitivity is higher	Select A3950SLPTR-T only if peak load current remains below 2.0 A and board-level thermal design accommodates +1.2 W extra dissipation
TB6612FNG	2-channel H-bridge (dual independent bridges), lower voltage rating (15 V max), no internal charge pump	Requires external bootstrap or high-side driver; better suited for dual-motor or low-voltage (<12 V) applications	Choose TB6612FNG when driving two separate small motors or when VBB < 12 V; not drop-in for A3949SLPTR-T due to different voltage and topology

Compared with A3949SLPTR-T, the A3950SLPTR-T offers identical footprint and control interface but trades efficiency for cost, while the TB6612FNG provides dual-bridge flexibility at the expense of voltage capability and integrated high-side drive-neither is pin-compatible, requiring PCB redesign for substitution.

Availability

A3949SLPTR-T is available at Aetrix Electronics and suitable for automotive power seats, industrial linear actuators, medical infusion pumps, and consumer robotics platforms requiring stable component supply despite end-of-life status.

Supply support for A3949SLPTR-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 A3949 product line targets cost-sensitive, thermally constrained brushed DC motor control in automotive comfort systems and industrial motion applications, emphasizing integration of protection, efficiency, and compact packaging.

FAQ

Is the A3949SLPTR-T still in production?

No, the A3949SLPTR-T is a discontinued product as of June 2, 2014. Allegro MicroSystems no longer manufactures or supplies new units. Aetrix Electronics maintains limited legacy stock for existing design continuity, but the A3949SLPTR-T should not be selected for new designs. Customers are advised to evaluate the A3950SLPTR-T or other modern alternatives for new projects.

What is the function of the SLEEP pin on the A3949SLPTR-T?

The SLEEP pin on the A3949SLPTR-T is an active-high logic input that disables internal circuitry-including the charge pump, VREG regulator, and gate drivers-to reduce quiescent current to ≤10 μA. When pulled low, the A3949SLPTR-T enters sleep mode; a 1 ms stabilization delay is required after returning SLEEP high before applying PWM signals to allow the charge pump to recharge.

Can the A3949SLPTR-T drive a 36 V motor continuously?

The A3949SLPTR-T supports VBB up to 36 V DC, but continuous operation at this voltage depends on thermal management. With its R_DS(ON) of 0.3–0.48 Ω and 52°C/W junction-to-ambient thermal resistance (2-layer PCB), sustained 2.8 A output at 36 V exceeds safe power dissipation limits. For reliable 36 V use, derate current to ≤1.5 A or implement enhanced heatsinking per Allegro's LB package layout guidelines.

How does the A3949SLPTR-T implement braking?

The A3949SLPTR-T supports two braking modes: slow decay (via MODE = high + ENABLE = low) shorts motor terminals through both low-side FETs, while fast-decay synchronous rectification (MODE = low + ENABLE = low) alternates high/low-side conduction to dissipate back-EMF energy more rapidly. Braking current is limited by motor BEMF and winding resistance (I_BRK ≈ V_BEMF/R_L), and must stay within the A3949SLPTR-T's ±2.8 A absolute maximum rating.

What external components are required for stable operation of the A3949SLPTR-T?

The A3949SLPTR-T requires five mandatory external components: a 100 μF bulk capacitor on VBB, a 0.22 μF ceramic capacitor on VREG-to-GND, two 0.1 μF ceramics on CP1–CP2 and VCP–VBB, and a sense resistor on SENSE for optional current limiting. Omitting any of these compromises charge pump stability, low-side regulation, or fault protection-critical for robust A3949SLPTR-T operation.

A3949SLPTR-T Specifications

Product attributes: Attribute value

Manufacturer:: Allegro MicroSystems

Series:: -

Package/Case:: 16-TSSOP (0.173", 4.40mm Width) Exposed Pad

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-eTSSOP-EP

A3949SLPTR-T FAQ

1.How can I place an order for A3949SLPTR-T through Aetrix?

Please submit a Request for Quotation (RFQ) for A3949SLPTR-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 A3949SLPTR-T reliable?

The price and inventory of A3949SLPTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3949SLPTR-T is usually 5 days.

3.What payment methods are accepted for A3949SLPTR-T?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3949SLPTR-T transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for A3949SLPTR-T?

A3949SLPTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your A3949SLPTR-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 A3949SLPTR-T?

For technical support, including A3949SLPTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3949SLPTR-T requirements.

6.How does Aetrix verify that A3949SLPTR-T is sourced from the original manufacturer or authorized distributors?

All A3949SLPTR-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 A3949SLPTR-T meets industry standards.

7.What is the process for return or replacement of A3949SLPTR-T?

All A3949SLPTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A3949SLPTR-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 A3949SLPTR-T part is unused and in its original packaging.

Return procedure for A3949SLPTR-T:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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