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Data Sheet

TWO PHASE DUAL-COIL CMOS SMART FAN MOTOR DRIVER AH9279

Oct. 2011 Rev. 1. 3 BCD Semiconductor Manufacturing Limited

General Description

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 MOS

FET 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.

The AH9279 is available in TO-94 package.

Features

• 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)

Applications

• Dual-coil Brushless DC Fan

Figure 1. Package Type of AH9279

TO-94

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