AH285

AH285 HALL-EFFECT SMART FAN MOTOR CONTROLLER Description Pin Assignments The AH285 is a single-chip solution for driving two-coil brushless direct current (BLDC) fans and motors. The device includes a Hall-effect sensor, dynamic offset correction and two complementary open-drain output drivers with internal Zener diode protection. To help protect the motor coils, the AH285 provides Rotor Lock Protection which shuts down output drives if rotor lock is detected. The device automatically re-starts when the rotor lock is removed. A Tachometer output is provided by open-drain Frequency Generator (FG) Pin which allows external interface to monitor motor rotation or speed. The FG output is the magnetic change frequency. The AH285 is available in SOT89-5L package. (Top View) Vdd 1 5 FG GND 2 285 DO 3 74 DOB SOT89-5L Features Applications Single-chip solution Operating Voltage: 3.8V to 20V Built-in Hall sensor and input amplifier Tachometer (FG) output Rotor Lock Protection (Lock detection, output shutdown and automatic re-start) Built-in Zener protection for output driver Average output current up to 500mA Packaged in SOT89-5L Green Molding Compound Two-coil BLDC cooling fans Low to medium voltage, low power BLDC motors Typical Application Circuit Vdd (12V) D2 FG D3 D1 Rpu C3 54 285 123 GND Coil2 Coil1 R1 R2 C1 C2 Notes: 12V DC Brush-less Fan with FG output function 1. Typically it is recommended to us a 56 Ohm resistor for R1 and R2 and a ...