Diodes Incorporated
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AH291 (Obsolete)

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AH291 is a monolithic fan motor controller with Hall sensor’s capability. It contains two complementary open-collector drivers for motor’s coil driving, automatic lock shutdown and restart function relatively. Rotor-lock shutdown detection circuit turns off the output driver when the rotor is blocked to avoid coil overheat. Then, the automatic recovery circuit will restart the motor. These protected actions are repeated and periodic during the blocked period. Until the blocking is removed, the motor recovers and runs normally.


  • On Chip Hall Sensor
  • Rotor-Locked Shutdown
  • Automatically Restart
  • Built-in Zener Protection for Output Driver
  • Operating Voltage: 1.8V to 5.75V
  • Output Current: IO(AVE)= 400mA
  • Packages: SIP-4L and SOT89-5L
  • Green Molding Compound


  • Two-coil BLDC cooling fans
  • Low to medium voltage, low power BLDC motors

Product Specifications

Product Parameters

Average OutputDrive Current (mA) 400
Frequency Generator (FG) and Rotation Detect -
Lock Detect, Shut-Down and Auto Start Yes
Operating Ambient Temperature (°C) -20 to 100
Operating Point Bop Gauss (Max) 60
Operating Point Bop Gauss (Min) -
Operating Point Bop Gauss (Typ) 30
Operating Voltage (V) 1.8 to 5.75
Peak Output Current (mA) 700
Release Point Brp Gauss (Max) -
Release Point Brp Gauss (Min) -60
Release Point Brp Gauss (Typ) -30
SupplyCurrent (mA) 2.6
Typical Total RDS(ON)(NMOS and PMOS Combined) 1.75 @ 5V
Typical Zener Breakdown Voltage (V) 15

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