A5947 3-Phase Sensorless Fan Driver IC

By Allegro MicroSystems, LLC 65

A5947 3-Phase Sensorless Fan Driver IC

Allegro's A5947 is an AEC-Q100 qualified, 40 V BLDC driver with integrated MOSFETs. The A5947 device is a highly efficient sinusoidal algorithm that is designed to meet the market demand for BLDC fan drivers while providing an easy-to-implement code-free solution.

The A5947 is ideal for a wide range of cooling fan systems including automotive seat ventilation, battery-cooling, ADAS GPU/CPU cooling fans, and server/telecom cooling fans. The fan driver features a built-in full-sinusoidal sensorless BLDC control algorithm and a programmable speed curve that eliminates the need for an external microcontroller (MCU) and software development. The fan driver reduces PCB space by including multiple external components such as MOSFETs. Allegro’s proprietary algorithm includes zero-torque position detection (ZTPD) and automatic phase advance to improve startup performance and enhance motor efficiency at high speeds. The A5947 is offered in two versions. The automotive-grade is available in a 24L eTSSOP (LP) package and the industrial-grade is available in a 28L QFN (ET) package.

  • Software Registration Portal
  • Supply voltage: 40 V (max)
  • Sensorless sinusoidal modulation
  • Protection: OCL, OCP, and lock detection
  • Integrated IP reduces user development cycle time
  • Minimal external components
  • Sinusoidal driver: improves efficiency and lower audible noise
  • Automatic phase advance: improves efficiency at high RPMs
  • Programmable speed curve
  • Close-loop speed control
  • Easy-to-use GUI for speed curve settings:
    • Reduces engineering evaluation time
    • No software code to write or debug
  • Zero-torque position detection:
    • Avoids motor reverse startup
    • Enhances startup speed
    • Eliminates audible noise during startup
  • Programmable speed curve:
    • Eliminates the need for an MCU
    • Enables a larger PCB GND plane for better thermals
    • Reduces inventory cost allowing the same PCB to be used for many applications
  • PWM speed input
  • FG speed output
  • Soft-start improves low-noise performance
  • Automotive:
    • Seat ventilation fans
    • ADAS GPU/CPU cooling fans
    • Battery-cooling fans
  • Telecom, server, and datacenter cooling fans
  • IC&C GPU/CPU cooling fans

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