TWO PHASE HALL-EFFECT SMART FAN MOTOR CONTROLLER
The AH2985 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. It is
optimized for low start-up voltage.
To help protect the motor coils, the AH2985 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.
Over temperature shutdown provides thermal protection for the
The AH2985 is available in TO94 package.
12 3 4
1 : VDD
2 : DO
3 : DOB
4 : GND
Operating Voltage: 2.5V to 15V
Built-in Hall Sensor and Input Amplifier
Rotor Lock Protection (Lock Detection, Output Shutdown and
Built-in Reverse Voltage Protection Diode
Built-in Zener Protection for Output Drivers
Average Output Current up to 500mA
“Green” Molding Compound
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Two-Coil BLDC Cooling Fans
Low Voltage/ Low Power BLDC Motors
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
Typical Applications Circuit (Note 4)
VDD DO DOB GND
12V Brushless DC Fan
Note: 4. D1 (Zener Diode) and Capacitor C are for power stabilization. Recommended value of C is 1μF/ 50V (E-Cap). Diode D2 is optional and helps to protect the
device and fan coils from reverse power conditions. The AH2985 also includes an internal reverse blocking diode at VDD pin.
Document number: DS38175 Rev. 1 - 2
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