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

Allegro MicroSystems A3936SED

Name: A3936SED
Brand: Allegro MicroSystems
SKU: A3936SED
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: A3936SED

Manufacturer:: Allegro MicroSystems

Category:: Motor Drivers, Controllers

Package:: 44-LCC (J-Lead)

Datasheet:: A3936SED.pdf

Description:: IC MOTOR DRIVER 3V-5.5V 44PLCC

Quantity:: RFQ Add To RFQ list

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Product details

Overview

A3936SED from Allegro MicroSystems is a three-phase brushless DC motor driver IC with ±3 A peak output current, 50 V operating voltage, and integrated fixed off-time PWM current control supporting slow/fast/mixed decay modes. It features synchronous rectification, tachometer output, thermal shutdown with hysteresis, and crossover-current protection - deployed in industrial BLDC motor control systems requiring precise commutation and efficient power dissipation.

For engineers reviewing the A3936SED datasheet, A3936SED pinout, A3936SED application, or A3936SED equivalent, key selection criteria include its 44-pin PLCC package with fused ground leads, Hall-effect sensor interface compatibility, internal charge pump for high-side drive, and configurable decay timing via PFD1/PFD2 pins.

Technical Context

The A3936SED implements a DMOS-based three-phase H-bridge architecture with independent source/sink drivers (r_DS(on) = 0.55 Ω source / 0.35 Ω sink), internally regulated VREG and charge pump (VCP) supplies, and Hall-input commutation logic supporting 120° electrical spacing. Its fixed off-time PWM timer (typically 24 µs at 4 MHz oscillator) directly governs current regulation via VREF and external sense resistor.

Control is managed through dedicated logic inputs: DIR sets rotation direction, ENABLE enables external PWM gating, EXTMODE selects fast/slow decay, SR activates synchronous rectification, and BRAKE forces three-sink shorting. TACH provides open-collector speed feedback toggling on each Hall transition.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Current	±3 A peak - supports mid-power BLDC motors up to ~150 W with adequate heatsinking
Supply Voltage	9–50 V load supply (VBB) - compatible with 12 V, 24 V, and 48 V industrial bus rails
r_DS(on)	0.55 Ω (source), 0.35 Ω (sink) - reduces conduction loss and thermal stress during PWM operation
PWM Timing	Fixed off-time ≈24 µs - ensures consistent current decay duration across temperature and supply variations
Operating Temp	–20°C to +85°C ambient - validated for enclosed industrial enclosures without forced air
Tach Output	Open-collector, edge-triggered per Hall transition - enables direct connection to MCU counter/timer peripherals
Protection	Thermal shutdown at 165°C with 15°C hysteresis + UVLO (2.7 V enable threshold) - prevents latch-up during brown-out or overtemperature events

Pinout & Package

The A3936SED is housed in a 44-pin plastic leaded chip carrier (PLCC) with fused ground leads (three per side) electrically tied to GND and thermally optimized for PCB heat spreading. The exposed power ground tab (Pin 44) serves as primary thermal path.

Pin/Terminal	Circuit Role	Design Meaning
GND (Pins 1,2,11,12,13,22,23,24,33,34,35,44)	Power and signal ground reference	Multiple low-inductance paths reduce ground bounce; fused leads (Pins 1,2,11,12,13,22,23,24,33,34,35,44) enhance thermal conduction to PCB
HA+/HA−, HB+/HB−, HC+/HC− (Pins 3–8)	Hall-effect sensor differential inputs	Accept 120° spaced digital Hall signals; support common-mode range of 0.3–2.5 V and 10–30 mV hysteresis
VBB1/VBB2 (Pins 19,26)	Motor supply input terminals	Dual VBB pins reduce IR drop and improve current sharing across high-current motor phases
OUTA/OUTB/OUTC (Pins 17,21,28)	DMOS H-bridge phase outputs	Drive motor windings directly; each capable of ±3 A peak with internal body diodes and synchronous rectification control
SENSE (Pin 15)	Current sense node	Connects to low-side sense resistor; trip threshold set by I_TRIP = VREF/(10 × R_SENSE)
VCP/CP1/CP2 (Pins 29–31)	Charge pump circuit nodes	VCP is reservoir capacitor terminal; CP1/CP2 require 0.22 µF ceramic caps to generate gate drive voltage > VBB for high-side DMOS
VREG (Pin 37)	Internal regulator output	Decoupled with 0.22 µF cap; powers sink-side drivers and is monitored for fault shutdown
TACH (Pin 27)	Speed feedback output	Open-collector output toggling on every Hall transition - provides 6 pulses per electrical revolution

Key Features

Feature	Design Value
Configurable current-decay modes	Slow/fast/mixed decay selected via PFD1/PFD2 pins - enables optimization of torque ripple, efficiency, and acoustic noise per motor design
Synchronous rectification	SR pin enables MOSFET-based recirculation path - replaces lossy body diodes, reducing power dissipation by >30% vs. diode-only decay
Integrated Hall commutation logic	Direct 120° Hall input interface with built-in bias (HBIAS) and pulse rejection filtering - eliminates need for external Schmitt triggers or level shifters
Brake function	BRAKE pin activates three-sink shorting - delivers rapid motor deceleration without PWM current limiting, useful for emergency stop or positioning
Thermal and electrical fault protection	Independent monitoring of VCP, VREG, and junction temperature - disables outputs within microseconds upon fault detection, preventing device destruction

Applications

Industrial Fan Control	Automated Gate Actuator
Use Scenario: Variable-speed cooling fan in PLC cabinet with thermal feedback loop. IC Role / Device Role / Timing Role: Three-phase BLDC driver executing Hall-based commutation and closed-loop current regulation. Use Value: Synchronous rectification lowers fan driver temperature rise by 12°C at full load, extending electrolytic capacitor life in high-temp environments.	Use Scenario: Bi-directional barrier gate in parking access system with position sensing and stall detection. IC Role / Device Role / Timing Role: Motor controller managing direction (DIR), braking (BRAKE), and speed (TACH) with overload protection. Use Value: Crossover-current protection prevents shoot-through during direction reversal, eliminating MOSFET failure during frequent start/stop cycles.
Medical Infusion Pump	Conveyor Belt Drive
Use Scenario: Precision peristaltic pump requiring smooth, low-vibration motor motion and accurate flow rate control. IC Role / Device Role / Timing Role: Fixed off-time PWM current controller regulating phase current to maintain constant torque across speed range. Use Value: Mixed-decay mode (15% fast, 85% slow) reduces audible motor whine below 25 dB(A) while maintaining <±2% speed regulation.	Use Scenario: Modular conveyor section with distributed BLDC drives and centralized PLC coordination. IC Role / Device Role / Timing Role: Local motor driver accepting direction and enable commands over discrete I/O, reporting speed via TACH. Use Value: Dual VBB pins (19 & 26) and multiple GND pins minimize voltage drop across 20 cm PCB traces, ensuring stable 48 V operation under 2.5 A continuous load.

Industrial Fan Control

Automated Gate Actuator

Use Scenario: Variable-speed cooling fan in PLC cabinet with thermal feedback loop.

IC Role / Device Role / Timing Role: Three-phase BLDC driver executing Hall-based commutation and closed-loop current regulation.

Use Value: Synchronous rectification lowers fan driver temperature rise by 12°C at full load, extending electrolytic capacitor life in high-temp environments.

Use Scenario: Bi-directional barrier gate in parking access system with position sensing and stall detection.

IC Role / Device Role / Timing Role: Motor controller managing direction (DIR), braking (BRAKE), and speed (TACH) with overload protection.

Use Value: Crossover-current protection prevents shoot-through during direction reversal, eliminating MOSFET failure during frequent start/stop cycles.

Medical Infusion Pump

Conveyor Belt Drive

Use Scenario: Precision peristaltic pump requiring smooth, low-vibration motor motion and accurate flow rate control.

IC Role / Device Role / Timing Role: Fixed off-time PWM current controller regulating phase current to maintain constant torque across speed range.

Use Value: Mixed-decay mode (15% fast, 85% slow) reduces audible motor whine below 25 dB(A) while maintaining <±2% speed regulation.

Use Scenario: Modular conveyor section with distributed BLDC drives and centralized PLC coordination.

IC Role / Device Role / Timing Role: Local motor driver accepting direction and enable commands over discrete I/O, reporting speed via TACH.

Use Value: Dual VBB pins (19 & 26) and multiple GND pins minimize voltage drop across 20 cm PCB traces, ensuring stable 48 V operation under 2.5 A continuous load.

Equivalent & Alternatives

The following parts are listed as comparable options for similar three-phase BLDC motor driver applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
STSPIN32F0A	Integrated 32-bit ARM Cortex-M0 MCU + gate drivers; requires external MOSFETs; no Hall inputs - uses embedded sensorless FOC	Best for compact, sensorless designs needing field-oriented control; not suitable for Hall-commutated legacy motors	Select when replacing aging Hall-based systems with modern FOC and firmware-defined motion profiles
DRV8313	3-A peak, 65-V max, SPI-configurable decay modes; includes current shunt amplifiers but no Hall interface or tach output	Requires external Hall decoder logic or MCU-based commutation; better suited for custom control algorithms	Choose for designs where SPI configurability and integrated current sensing outweigh need for native Hall support

Compared with STSPIN32F0A and DRV8313, the A3936SED offers plug-and-play Hall commutation, tach feedback, and fused-lead thermal packaging - making it optimal for retrofitting industrial BLDC systems without redesigning sensor interfaces or control firmware.

Availability

A3936SED is available at Aetrix Electronics and suitable for industrial fan control, automated gate actuation, medical infusion pumps, and conveyor belt drives requiring stable component supply and long-term obsolescence management.

Supply support for A3936SED 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 global leader in precision sensing and power ICs, specializing in magnetic sensing, motor driver, and power conversion solutions for automotive and industrial markets.

The A3936SED belongs to Allegro's high-voltage, Hall-commutated BLDC driver product line - engineered specifically for robust, cost-effective replacement of discrete MOSFET+logic motor control designs in factory automation and HVAC equipment.

FAQ

What is the maximum continuous output current rating of the A3936SED?

The A3936SED supports ±3 A peak output current, but continuous current is thermally limited. At TA = +25°C with adequate PCB copper area (≥4 in² 2-oz copper), continuous current is ~2.2 A. Derating is required above +25°C ambient - e.g., ~1.5 A at +70°C. Exceeding 150°C junction temperature triggers thermal shutdown.

Does the A3936SED require external MOSFETs or is it a fully integrated driver?

The A3936SED is a fully integrated three-phase DMOS motor driver - all high-side and low-side power switches are internal. No external MOSFETs are needed. It drives motor windings directly via OUTA/OUTB/OUTC pins, with integrated gate drive, charge pump (VCP), and regulator (VREG) circuitry.

How does the A3936SED implement current regulation without a microcontroller?

The A3936SED uses an internal fixed off-time PWM controller that compares sensed current (via SENSE pin and external resistor) against a threshold set by VREF. When current reaches I_TRIP = VREF/(10 × R_SENSE), the source driver turns off for a fixed duration (~24 µs), enabling autonomous current regulation independent of external timing sources.

Can the A3936SED operate with only two Hall sensors instead of three?

No - the A3936SED requires all three differential Hall pairs (HA+/HA−, HB+/HB−, HC+/HC−) for proper 120° commutation. Missing or mismatched Hall inputs cause undefined output states or failure to start. The internal commutation logic is hardwired for six-step trapezoidal drive using all three sensors.

What is the purpose of the fused ground leads on the A3936SED PLCC package?

The fused ground leads (Pins 1,2,11,12,13,22,23,24,33,34,35,44) are internally connected to the die substrate and provide low-thermal-resistance paths to the PCB. They serve as both electrical ground returns and primary heat conduction routes - critical for dissipating up to 3.9 W package power without external heatsinks.

A3936SED Specifications

Product attributes: Attribute value

Manufacturer:: Allegro MicroSystems

Series:: -

Package/Case:: 44-LCC (J-Lead)

Packaging:: Tube

Product Status:: Obsolete

Motor Type - Stepper:: -

Motor Type - AC, DC:: Brushless DC (BLDC)

Function:: Driver - Fully Integrated, Control and Power Stage

Output Configuration:: Half Bridge (3)

Interface:: Parallel

Technology:: DMOS

Step Resolution:: -

Applications:: General Purpose

Current - Output:: 3A

Voltage - Supply:: 3V ~ 5.5V

Voltage - Load:: 9V ~ 50V

Operating Temperature:: -20°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 44-PLCC (16.59x16.59)

A3936SED FAQ

1.How can I place an order for A3936SED through Aetrix?

Please submit a Request for Quotation (RFQ) for A3936SED 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 A3936SED reliable?

The price and inventory of A3936SED are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3936SED is usually 5 days.

3.What payment methods are accepted for A3936SED?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3936SED transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for A3936SED?

A3936SED orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your A3936SED 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 A3936SED?

For technical support, including A3936SED datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3936SED requirements.

6.How does Aetrix verify that A3936SED is sourced from the original manufacturer or authorized distributors?

All A3936SED 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 A3936SED meets industry standards.

7.What is the process for return or replacement of A3936SED?

All A3936SED units undergo pre-shipment inspection (PSI). If there is an issue with A3936SED, 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 A3936SED part is unused and in its original packaging.

Return procedure for A3936SED:

1.Submit a request within 90 days.

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

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