AH291 LOW VOLTAGE HALL-EFFECT SMART FAN MOTOR CONTROLLER Description Pin Assignments AH291 is a monolithic fan motor controller with Hall sensors (Top View) (Top View) capability. It contains two complementary open-collector drivers for motors coil driving, automatic lock shutdown and 291 Vdd 1 NC 5 restart function relatively. 1 : Vdd 2 : DO 291 Rotor-lock shutdown detection circuit turns off the output GND 2 driver when the rotor is blocked to avoid coil overheat. Then, 3 : DOB the automatic recovery circuit will restart the motor. These DO 3 74 DOB protected actions are repeated and periodic during the 4 : GND 12 3 4 blocked period. Until the blocking is removed, the motor SOT89-5L SIP-4L recovers and runs normally. The AH291 is available in SIP4 and SOT89-5L packages. Features Applications On Chip Hall Sensor Two-coil BLDC cooling fans Rotor-Locked Shutdown Low to medium voltage, low power BLDC motors Automatically Restart Built-in Zener Protection for Output Driver Operating Voltage: 1.8V to 5.75V Output Current: I = 400mA O(AVE) Packages: SIP-4L and SOT89-5L Green Molding Compound Typical Application Circuit (Note 1) D2 1.8V/5.75V V dd D1 291 L2 L1 12 3 4 GND C3 DOB DO R1 R2 Notes: 1. R1, R2: typical 56 Ohm C1, C2, C3: typical 2.2F The R, C value need to be fine tuned based on coils design. C1 C2 1.8V/5.75V Brush-Less DC Fan 1 of 9 June 2010 AH291 Diodes Incorporated www.diodes.com Document number: DS31041 Rev. 8 - 2 AH291 LOW VOLTAGE HALL-EFFECT SMART FAN MOTOR CONTROLLER Pin Descriptions Pin Name Description Vdd Input Power DO Output Pin DOB Output Pin GND Ground NC Not Connected Functional Block Diagram Vdd Lock detect, shutdown and automatic re-start Regulator DO Hall Plate Amp. Control Logic DOB GND 2 of 9 June 2010 AH291 Diodes Incorporated www.diodes.com Document number: DS31041 Rev. 8 - 2