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Three-Phase Sensorless BLDC Gate Drivers with Closed-Loop Speed Control designed for Data Center Cooling Systems

Three-Phase Sensorless BLDC Gate Drivers
Three-Phase Sensorless BLDC Gate Drivers

Allegro MicroSystems, Inc. has expanded its portfolio of three-phase sensorless BLDC gate drivers with the new A89332 and A89332-1 gate drivers that enable compact, high-airflow fan designs to improve thermal efficiency, reducing energy use and data center costs. As the leading code-free solution for data-center cooling fans, these drivers are integrated with a flexible closed-loop speed control system. Moreover, an EEPROM is used to tailor the common functions of the fan speed curve to a specific application which eliminates the requirement for a microprocessor-based system and minimizes programming requirements.


The A89332 three-phase sensorless fan controller helps reduce data-center costs and with power loss brake function, this gate driver IC can reduce energy consumption by stopping fans that have lost power or are not working properly. The A89331 three-phase motor driver with integrated MOSFETs offers sensorless control, eliminating the requirement for Hall sensors in server fan applications. It incorporates a sensorless sinusoidal driver to minimize vibration for high-speed server fans.



  • Closed-loop speed control

  • Power loss brake

  • Fault mode brake

  • Configurable rotor detect (RD) or frequency generator (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

  • Adjustable gate drive option

  • Minimal external components

  • PWM duty cycle speed input



  • High-speed 12 V server cooling fans

  • Industrial and consumer blowers and fans



The A89332 IC is available in a 26-contact 4 mm x 4 mm QFN with exposed pad (suffix EX). The A89331 IC is available in a 28-contact 5 mm x 5 mm QFN with an exposed power pad (suffix ET) and a 20-contact TSSOP with an exposed power pad (suffix LP).

Component Datasheet

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