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Two Phase 5V/12V BLDC All-In-One Fan and Motor Driver with Output Zener Clamp

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The AH9279 is a most advanced fan control and drive Hall IC manufactured by special CMOS process. This IC consists of voltage reference, Hall sensor, signal amplifier, wave shaping circuit, locked rotor detector, locked rotor protection and restart circuit, output drive circuit, etc.. To allow survival in a harsh environment and in consideration of low cost, the AH9279 has been designed with many functions internally, and requires less external components. When there is no motion for one second, the IC will detect locked rotor conditions, enter protection mode automatically and disable two outputs for five seconds. Then, it will turn on drive current from one channel for one second. If it still fails to detect fan rotation, the AH9279 will shut off the outputs for five seconds again. This sequence will be repeated until rotation condition is detected and the IC enters normal operation mode. This function prevents the chip from overheating and damage due to long time locked rotor. The power dissipation decides allowable maximum ambient temperature. Low power dissipation of AH9279 and the output MOSFET power transistor enable it to be used at ambient temperature up to 125°C on condition that the drive power is lower than 100mW or drive current is less than 200mA.


  • On Chip Hall Sensor
  • Built-in Zener Diodes Protection for Output Driver
  • Power Efficient CMOS and Power MOSFET Drivers Allow 400mA Without Overheating
  • 5V and 12V Operation
  • High Sensitivity for Switching Symmetry
  • Locked Rotor Shutdown and Auto Restart
  • ESD Rating: 4000V(Human Body Model) 400V(Machine Model)
  • Application(s)

  • Dual-coil Brushless DC Fan
  • Product Specifications

    Product Parameters

    Operating Voltage (V) 2.5 to 16 V
    SupplyCurrent (mA) 3.5 mA
    Average OutputDrive Current (mA) - mA
    Peak Output Current (mA) 500 mA
    Typical Total RDS(ON)(NMOS and PMOS Combined) 1.7 @ 12V Ω
    Typical Zener Breakdown Voltage (V) 35 V
    Operating Point Bop Gauss (Min) -
    Operating Point Bop Gauss (Typ) 25
    Operating Point Bop Gauss (Max) 50
    Release Point Brp Gauss (Min) -50
    Release Point Brp Gauss (Typ) -25
    Release Point Brp Gauss (Max) -
    Lock Detect, Shut-Down and Auto Start Yes
    Frequency Generator (FG) and Rotation Detect - RD
    Operating Ambient Temperature (°C) -20 to 125 °C

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