A89331 & A89331-1: Three-Phase Sensorless Drivers

Please contact us for the full datasheet of the A89331 and A89331-1.


The A89331 three-phase motor drivers incorporate sensorless sinusoidal drive to minimize vibration for high-speed server fans. Sensorless control eliminates the requirement for Hall sensors for server fan applications.

A flexible closed loop speed control system is integrated into the IC. EEPROM is used to tailor the common functions of the fan speed curve to a specific application. This eliminates the requirement for a microprocessor-based system and minimizes programming requirements.

The A89331 family is designed to offer the features best suited for your needs.  The A89331 offers power-loss braking (PLB) while the A89331-1 offers an AC loss feature. 

The A89331 ICs are available in a 28L 5x5 QFN with an exposed power pad (suffix ET) and a 20L TSSOP with an exposed power pad (suffix LP).

Featured Applications:

Server and Datacenter Cooling Fans

Top Features

  • Closed Loop Speed Control
  • Overvoltage Protection
  • Power Loss Brake – A89331
  • AC Loss – A89331-1
  • Fault Mode Brake
  • Configurable RD or FG Output
  • Speed Curve Configuration via EEPROM
  • I2C Serial port
  • Sinusoidal modulation for Reduced Audible Noise and Low vibration
  • Sensorless (No Hall Sensors required)
  • Trapezoidal Drive Option for High Speed
  • Low RDSON Power MOSFETs – 3A capability
  • Minimal External Components
  • PWM Duty Cycle Speed Input
  • FG Speed Output
  • Lock Detection
  • Soft Start
  • Shorted Load Protection

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
APEK89331GLP-01-T DEMO BOARD -20°C to 85°C No -- Contact your
local sales rep
Distributor Stock
A89331GETSR 28-lead QFN -40°C to 105°C Yes View Data Contact your
local sales rep
Distributor Stock
A89331GETSR-1 28-lead QFN -40°C to 105°C Yes View Data Contact your
local sales rep
Distributor Stock
A89331GLPTR-T 20-lead TSSOP -40°C to 105°C Yes View Data Contact your
local sales rep
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.


ET QFN with exposed pad 28 lead

28 contact QFN with exposed thermal pad (suffix ET) 

ET Package Documentation

20-Pin eTSSOP with exposed thermal pad LP Package

20L TSSOP with exposed thermal pad (suffix LP)

LP Package Documentation

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