AH9279

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 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.

Feature(s)

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