AH285-PL-B Diodes Incorporated

NOT RECOMMENDED FOR NEW DESIGN USE AH2985 AH285 HALL-EFFECT SMART FAN MOTOR CONTROLLER Description Pin Assignments The AH285 is a single-chip solution for driving two-coil brushless (Top View) direct current (BLDC) fans and motors. The device includes a Hall- effect sensor, dynamic offset correction and two complementary Vdd 1 FG 5 open-drain output drivers with internal Zener diode protection. 285 GND 2 To help protect the motor coils, the AH285 provides Rotor Lock Protection which shuts down output drives if rotor lock is detected. DO DOB 3 74 The device automatically re-starts when the rotor lock is removed. SOT89-5 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 SOT89-5 package. Features Applications Single-chip Solution Operating Voltage: 3.8V to 20V Two-coil BLDC Cooling Fans Built-in Hall Sensor and Input Amplifier Low to Medium Voltage, Low Power BLDC Motors 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 SOT89-5 Green Molding Compound Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. Green Device (Note 3) Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. 2. See NOT RECOMMENDED FOR NEW DESIGN AH285 USE AH2985 Typical Application Circuit (Note 4) D2 Vdd (12V) R D1 pu 5 4 Coil2 FG 285 Coil1 1 2 3 D3 C3 R1 R2 GND C2 C1 12V DC Brush-less Fan with FG Output Function Notes: 4. Typically it is recommended to us a 56 resistor for R1 and R2 and a 2.2F E-Cap capacitor for C1, C2 and C3. These values may need to be optimized depending on the coils used. To help with IC protection its advised to add a Zener diode between Vdd and ground. The Zener diode should be chosen to help prevent the supply voltage exceeding the maximum rating of the device. Pin Descriptions Pin Name Description FG Frequency Generation Vdd Input Power DO Output Pin DOB Output Pin GND Ground 2 of 10 AH285 June 2017 Diodes Incorporated www.diodes.com Document number: DS31029 Rev. 9 - 3 OBSOLETE PART DISCONTINUED