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

Allegro MicroSystems A5931GESTR-1-T

Name: A5931GESTR-1-T
Brand: Allegro MicroSystems
SKU: A5931GESTR-1-T
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: A5931GESTR-1-T

Manufacturer:: Allegro MicroSystems

Category:: Motor Drivers, Controllers

Package:: 24-WFQFN Exposed Pad

Datasheet:: A5931GESTR-1-T.pdf

Description:: 5931 WITH DELL SPEED CURVE, FORC

Quantity:: RFQ Add To RFQ list

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Product details

Overview

A5931GESTR-1-T from Allegro MicroSystems is a three-phase sensorless sinusoidal fan driver IC designed for high-speed server fans, delivering 3 A motor phase current, closed-loop speed control via configurable EEPROM, and I²C serial interface - eliminating Hall sensors and external microcontrollers in thermal management systems.

For engineers reviewing the A5931GESTR-1-T datasheet, A5931GESTR-1-T pinout, A5931GESTR-1-T application, or A5931GESTR-1-T equivalent, key selection criteria include its 24-pin QFN (4 mm × 4 mm) package with exposed thermal pad, -40°C to +105°C operating range, integrated low-R_DS(ON) MOSFETs, FG/RD/SPD signal interface, and EEPROM-tailored speed curve configuration for server-grade fan control.

Technical Context

The A5931GESTR-1-T implements sensorless back-EMF position detection to enable sinusoidal commutation without Hall sensors, reducing audible noise and mechanical vibration. Its closed-loop speed control uses a 9-bit PWM duty input (6–100 kHz), converted internally to RPM demand using EEPROM-defined slope and offset parameters.

It integrates a charge-pump-based gate driver, thermal shutdown (150–180°C), overcurrent protection (~6.5 A), lock detection with programmable RD output timing, and standby mode triggered by SPD pin assertion - all managed through on-chip logic without MCU intervention.

Key Specifications

Parameter	Value and Actual Design Meaning
Motor Drive Type	Sensorless three-phase sinusoidal commutation - eliminates need for Hall sensors and reduces acoustic noise in server fans.
Max Motor Phase Current	3000 mA - supports high-airflow server fan motors with continuous sinusoidal operation.
Supply Voltage Range	5 V to 16 V DC - compatible with standard 12 V server fan rails and tolerant of transient overvoltage up to 20 V (10 ms).
Speed Control Interface	PWM input (6–100 kHz) or I²C serial command - enables flexible integration with host controllers or direct register writes to address 165.
EEPROM Configuration	User-programmable speed curve, lock thresholds, ramp profiles, and protection timing - eliminates firmware development for fan control logic.
Thermal Protection	Thermal shutdown at 150–180°C with 20°C hysteresis - ensures reliability under sustained overload or poor heatsinking conditions.
Package Thermal Resistance	45 °C/W (θ_JA, 2-sided PCB, 1-in² copper) - enables high-power density fan drive in compact 4 mm × 4 mm QFN layout.

Pinout & Package

Package: 24-contact QFN (ES), 4 mm × 4 mm × 0.75 mm, exposed thermal pad - RoHS-compliant, lead-free, matte-tin plated leadframe.

Pin/Terminal	Circuit Role	Design Meaning
1, 23	GND	Power and signal ground reference - must be connected to low-impedance PCB plane for stable motor current return and noise immunity.
2, 3	FG, RD	Open-drain outputs - FG provides tachometer signal (2 pulses/rev); RD signals rotor lock fault; both share I²C SDA functionality.
4, 21	DIR, CTAP	Direction control (ES only) and motor common tap (Wye motors) - DIR enables A→B→C or A→C→B sequencing; CTAP requires 2 kΩ series resistor if used.
6, 13	LSS	Low-side source connection - ties internal low-side MOSFET sources to power ground; critical for accurate current sensing and OCP operation.
7, 9, 12	OUTA, OUTB, OUTC	Three-phase motor terminal outputs - drive BLDC fan windings with integrated 210–250 mΩ R_DS(ON) (T_J = 25°C) MOSFETs.
8, 11	VBB	Main power supply input - accepts 5–16 V DC; dual VBB pins reduce IR drop and improve thermal distribution across package.
14–16, 19, 24	VCP, CP1, CP2, VREF, PAD	Charge pump capacitor nodes, 2.85 V reference output, and exposed thermal pad - VREF powers external circuitry; PAD must be soldered to PCB thermal plane for thermal performance.

Key Features

Feature	Design Value
Sinusoidal modulation	Reduces torque ripple and audible noise vs. trapezoidal drive - essential for low-vibration server fan applications.
I²C serial interface (0x55)	Enables real-time speed control and EEPROM reprogramming without halting system operation - supports factory tuning and field updates.
Configurable speed curve	EEPROM-stored MINSPD, SPDSLP1, DCON/DCOFF, and dual-slope options allow precise RPM vs. PWM mapping per fan model.
Integrated protection suite	Lock detection (RD), thermal shutdown, overcurrent limit (6.5 A), VBB UVLO (4.3 V), and short-circuit protection - reduces external component count and BOM cost.
Standby mode	Activated by holding SPD low > t_LOCK - cuts quiescent current to ≤100 µA, enabling energy-efficient fan idle states in datacenter thermal management.

Applications

Data Center Server Fans	High-Density Rack Cooling Systems
Use Scenario: High-RPM (>20,000 RPM) 12 V BLDC fans in 1U/2U servers requiring silent, vibration-free airflow under variable thermal loads. IC Role / Device Role / Timing Role: Primary motor controller executing sensorless sinusoidal commutation, closed-loop speed regulation, and rotor lock monitoring. Use Value: Eliminates Hall sensors and MCU, reduces PCB area by >30%, and achieves <±5% speed accuracy across temperature via EEPROM-trimmed curves.	Use Scenario: Multi-fan arrays in telecom and edge computing racks where coordinated speed control minimizes acoustic interference and airflow turbulence. IC Role / Device Role / Timing Role: Distributed fan driver with I²C addressability (0x55), enabling synchronized speed ramping and individual fault reporting via RD/FG lines. Use Value: Supports daisy-chained I²C bus for centralized thermal management, with programmable t_LOCK and RD blank time ensuring consistent startup across fan units.
Enterprise Storage Enclosures	AI Accelerator Chassis Cooling
Use Scenario: Redundant cooling in JBOD/NAS enclosures where fan failure detection and graceful degradation are mandatory for data integrity. IC Role / Device Role / Timing Role: Fault-aware driver providing RD output for lock condition, FG for speed telemetry, and EEPROM-configurable fail-safe behavior. Use Value: RD signal enables immediate host-level alerting; EEPROM-programmed RD_HIGH/RD_LOW thresholds support application-specific lock sensitivity.	Use Scenario: High-power GPU/AI module cooling where rapid thermal transients demand fast response (<500 ms) and robust overcurrent protection during startup surges. IC Role / Device Role / Timing Role: High-current (3 A) motor driver with soft-start, programmable acceleration (ACCEL), and OCP threshold override via EEPROM. Use Value: Prevents inrush-induced MOSFET stress with adjustable STRTF/ACCELT parameters; OCL bits allow current limiting at 1–3.2 A to match thermal envelope.

Data Center Server Fans

High-Density Rack Cooling Systems

Use Scenario: High-RPM (>20,000 RPM) 12 V BLDC fans in 1U/2U servers requiring silent, vibration-free airflow under variable thermal loads.

IC Role / Device Role / Timing Role: Primary motor controller executing sensorless sinusoidal commutation, closed-loop speed regulation, and rotor lock monitoring.

Use Value: Eliminates Hall sensors and MCU, reduces PCB area by >30%, and achieves <±5% speed accuracy across temperature via EEPROM-trimmed curves.

Use Scenario: Multi-fan arrays in telecom and edge computing racks where coordinated speed control minimizes acoustic interference and airflow turbulence.

IC Role / Device Role / Timing Role: Distributed fan driver with I²C addressability (0x55), enabling synchronized speed ramping and individual fault reporting via RD/FG lines.

Use Value: Supports daisy-chained I²C bus for centralized thermal management, with programmable t_LOCK and RD blank time ensuring consistent startup across fan units.

Enterprise Storage Enclosures

AI Accelerator Chassis Cooling

Use Scenario: Redundant cooling in JBOD/NAS enclosures where fan failure detection and graceful degradation are mandatory for data integrity.

IC Role / Device Role / Timing Role: Fault-aware driver providing RD output for lock condition, FG for speed telemetry, and EEPROM-configurable fail-safe behavior.

Use Value: RD signal enables immediate host-level alerting; EEPROM-programmed RD_HIGH/RD_LOW thresholds support application-specific lock sensitivity.

Use Scenario: High-power GPU/AI module cooling where rapid thermal transients demand fast response (<500 ms) and robust overcurrent protection during startup surges.

IC Role / Device Role / Timing Role: High-current (3 A) motor driver with soft-start, programmable acceleration (ACCEL), and OCP threshold override via EEPROM.

Use Value: Prevents inrush-induced MOSFET stress with adjustable STRTF/ACCELT parameters; OCL bits allow current limiting at 1–3.2 A to match thermal envelope.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MP6550GQ-Z	Single-chip 3-phase gate driver (no integrated MOSFETs); requires external high-side/low-side FETs; no EEPROM or closed-loop speed control.	Used in custom fan designs where discrete power stage optimization is required; lacks integrated speed regulation logic.	Select MP6550GQ-Z only when designing for variable motor types, higher voltage (>16 V), or when full control over gate timing and dead time is needed.
DRV10983ZRTVT	Integrated 3-phase driver with Hall sensor interface; supports both sensor-based and sensorless modes; includes analog speed input but no I²C interface.	Preferred for mixed-fan fleets where some units retain Hall sensors; lacks EEPROM configurability and RD fault signaling granularity.	Choose DRV10983ZRTVT if backward compatibility with legacy Hall-equipped fans is required, or when I²C is unavailable in system architecture.

Compared with MP6550GQ-Z and DRV10983ZRTVT, the A5931GESTR-1-T uniquely combines integrated power MOSFETs, EEPROM-configurable closed-loop speed control, I²C programmability, and dedicated RD fault signaling - making it optimal for high-volume, low-noise server fan modules where BOM simplification and acoustic performance are critical.

Availability

A5931GESTR-1-T is available at Aetrix Electronics and suitable for data center server cooling, high-density rack thermal management, and enterprise storage enclosure fan control requiring stable component supply, long-term lifecycle support, and qualified industrial-grade operation.

Supply support for A5931GESTR-1-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, specializing in motion control, motor drivers, and precision current sensing.

The A5931 product line targets high-efficiency, low-noise thermal management in datacenter infrastructure - delivering integrated sensorless BLDC control with programmable speed profiles and robust protection for mission-critical cooling applications.

FAQ

What is the operating temperature range for the A5931GESTR-1-T?

The A5931GESTR-1-T is rated for an operating temperature range of –40°C to +105°C (Grade G), validated per Allegro's characterization and supported by thermal resistance data (θ_JA = 45°C/W). This makes it suitable for deployment inside thermally demanding server chassis environments where ambient temperatures exceed 70°C near CPU/GPU heat sources. The A5931GESTR-1-T maintains full functional specification across this range without derating.

Does the A5931GESTR-1-T require external Hall sensors for motor commutation?

No, the A5931GESTR-1-T implements sensorless back-EMF detection for three-phase sinusoidal commutation, eliminating the need for external Hall sensors. It derives rotor position from motor winding voltage signatures during rotation, enabling smooth, low-vibration operation in server fans. This architecture reduces system cost, PCB space, and assembly complexity - a core design objective confirmed in the A5931GESTR-1-T datasheet description and functional block diagram.

How is speed controlled on the A5931GESTR-1-T - via PWM or analog voltage?

Speed on the A5931GESTR-1-T is controlled primarily via a 6–100 kHz PWM input on the SPD pin, with duty cycle mapped to RPM using EEPROM-configured slope and offset parameters. While the K-version supports analog voltage input, the A5931GESTR-1-T (G-version, ES package) defaults to PWM mode per its EEPROM bit SPDSEL = 0. Analog control is not enabled unless explicitly programmed - and even then, it is not supported in the G-grade ES package variant.

What protection features does the A5931GESTR-1-T include?

The A5931GESTR-1-T integrates lock detection (reported via RD output), thermal shutdown (150–180°C), overcurrent protection (~6.5 A), VBB undervoltage lockout (4.3 V), and short-circuit protection. These functions operate autonomously without host intervention. The RD pin's behavior - including blank time, delay, and high/low thresholds - is fully configurable via EEPROM parameters LOCKEVT, RDBLANK, RDDLY, RDHIGH, and RDLOW, enabling precise fault response tuning for specific fan models.

Can the A5931GESTR-1-T be programmed after soldering to the PCB?

Yes, the A5931GESTR-1-T supports in-system programming via its I²C interface (7-bit address 0x55), using the SPD pin as SCL and FG as SDA. EEPROM contents - including speed curves, protection thresholds, and startup parameters - can be updated post-assembly using Allegro's GUI software and EVB hardware. This allows final calibration, field updates, and customization without rework, provided the I²C bus is accessible and pull-up resistors are installed per datasheet recommendations.

A5931GESTR-1-T Specifications

Product attributes: Attribute value

Manufacturer:: Allegro MicroSystems

Series:: -

Package/Case:: 24-WFQFN Exposed Pad

Packaging:: Bulk

Product Status:: Active

Motor Type - Stepper:: Multiphase

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

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

Output Configuration:: Half Bridge (3)

Interface:: Analog, I2C, PWM

Technology:: Power MOSFET

Step Resolution:: -

Applications:: Fan Motor Driver

Current - Output:: 3A

Voltage - Supply:: 5V ~ 16V

Voltage - Load:: 5V ~ 16V

Operating Temperature:: -40°C ~ 105°C (TA)

Grade:: Automotive

Qualification:: AEC-Q100

Mounting Type:: Surface Mount

Supplier Device Package:: 24-QFN (4x4)

A5931GESTR-1-T FAQ

1.How can I place an order for A5931GESTR-1-T through Aetrix?

Please submit a Request for Quotation (RFQ) for A5931GESTR-1-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 A5931GESTR-1-T reliable?

The price and inventory of A5931GESTR-1-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A5931GESTR-1-T is usually 5 days.

3.What payment methods are accepted for A5931GESTR-1-T?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A5931GESTR-1-T transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for A5931GESTR-1-T?

A5931GESTR-1-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your A5931GESTR-1-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 A5931GESTR-1-T?

For technical support, including A5931GESTR-1-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A5931GESTR-1-T requirements.

6.How does Aetrix verify that A5931GESTR-1-T is sourced from the original manufacturer or authorized distributors?

All A5931GESTR-1-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 A5931GESTR-1-T meets industry standards.

7.What is the process for return or replacement of A5931GESTR-1-T?

All A5931GESTR-1-T units undergo pre-shipment inspection (PSI). If there is an issue with A5931GESTR-1-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 A5931GESTR-1-T part is unused and in its original packaging.

Return procedure for A5931GESTR-1-T:

1.Submit a request within 90 days.

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

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