Diodes AH2984 User Manual
A
TWO PHASE HALL-EFFECT SMART FAN MOTOR CONTROLLER
Description
The AH2984 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 AH2984 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
device.
The AH2984 is available in SIP4 and SOT89-5 packages.
Features
Pin Assignments
Vdd
(Top View)
AH2984
1 2 4 3
SIP- 4
(Top View)
1
H2984
1 : V
DD
2 : DO
3 : DOB
4 : GND
NC
5
• Single-chip solution
• Operating Voltage: 2.5V to 15V
• Built-in Hall sensor and input amplifier
• Rotor Lock Protection (Lock detection, output shutdown and
automatic re-start)
• Built-in reverse voltage protection diode
• Built-in Zener protection for output drivers
• Average output current up to 500mA
• Packages: SIP-4 and 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 http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
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.
Applications
• Two-coil BLDC Cooling Fans
• Low Voltage/ Low Power BLDC Motors
GND
AH2984
2
3 7
SOT89-5
4
GND
DOBDO
AH2984
Document number: DS31698 Rev. 4 - 2
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Typical Applications Circuit (Note 4)
(1) For SIP-4
12V
Vdd
H2984
D2
(2) For SOT89-5
Vdd
(12V)
D1
D1
AH2984
Vdd DO DOB G ND
1234
C
12V Brushless DC Fan
5 4
NC DOB
AH2984
Vdd DOGND
132
C
L1 L2
GND
D2
GND
L1
L2
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 AH2984 also includes an internal reverse blocking diode at V
Pin Descriptions
AH2984
Document number: DS31698 Rev. 4 - 2
Pin Name SIP-4 SOT89-5 Description
VDD
DO 2 3 Output Pin
DOB 3 4 Output Pin
GND 4 2 Ground
NC — 5 No Connection
1 1 Input Power
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GND
pin.
DD
December 2013
© Diodes Incorporated
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Functional Block Diagram
(1) For SIP-4
Vdd
1
Regulator
Hall
Plate
Amp.
Lock detect,
Shutdown and
Automatic re-start
Control Logic
2
3
H2984
DO
DOB
(2) For SOT89-5
Vdd
1
Regulator
Hall
Plate
Amp.
4
GND
Lock detect,
Shutdown and
Automatic re-start
Control Logic
5
3
4
NC
DO
DOB
2
GND
AH2984
Document number: DS31698 Rev. 4 - 2
3 of 10
www.diodes.com
December 2013
© Diodes Incorporated
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