Diodes AH284 User Manual
AH284
HALL-EFFECT SMART FAN MOTOR CONTROLLER
Description
The AH284 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 AH284 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.
The AH284 is available in SIP4 and SOT89-5L packages.
Features
• Single-chip solution
• Operating Voltage: 3.8V to 20V
• Built-in Hall sensor and input amplifier
• Rotor Lock Protection (Lock detection, output shutdown
and automatic re-start)
• Built-in Zener protection for output driver
• Average output current up to 500mA
• Packages: SIP-4L and SOT89-5L
• Green Molding Compound
Pin Assignments
(Top View)
284
12 43
SIP-4L
1 : Vdd
2 : DO
3 : DOB
4 : GND
Vdd
GND
(Top View)
1
284
2
3 7
SOT89-5L
Applications
• Two-coil BLDC cooling fans
• Low to medium voltage, low power BLDC motors
NC
5
DOBDO
4
Typical Application Circuit (Note 1)
12V
D3
Notes: 1. Typically it is recommended to us a 56 Ohm resistor for R1 and R2 and a 2.2μF 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 it’s 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.
V
dd
D1
C3
D2
284
1234
DO
L2 L1
GND
DOB
R1 R2
C1 C2
AH284
Document number: DS31051 Rev. 11 - 2
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www.diodes.com
June 2010
© Diodes Incorporated
Pin Descriptions
Pin Name Description
Vdd Input Power
DO Output Pin
DOB Output Pin
GND Ground
NC Not Connected
Functional Block Diagram
Vdd
Regulator
AH284
HALL-EFFECT SMART FAN MOTOR CONTROLLER
Lock detect,
shutdown and
automatic re-start
DO
Hall
Plate
Amp.
Control Logic
DOB
GND
AH284
Document number: DS31051 Rev. 11 - 2
2 of 10
www.diodes.com
June 2010
© Diodes Incorporated
AH284
θJAθ
HALL-EFFECT SMART FAN MOTOR CONTROLLER
Absolute Maximum Ratings (T
Symbol Characteristics Rating Unit
Vdd Supply Voltage 24 V
IO Output Current
PD Power Dissipation
TST Storage Temperature -55 ~ 150
TJ Maximum Junction Temperature 150
θ
JA
Thermal Resistance Junction to
Case (Note 2)
= 25°C)
A
TJ
I
O (AVE)
I
O (PEAK)
SIP-4L 500 mA
SOT89-5L 500 mA
700 mA
SIP-4L 550 mW
SOT89-5L 800 mW
SIP-4L 227
SOT89-5L 156
TA
Tc
°C
°C
°C/W
°C/W
JC
Notes: 2. θJA should be confirmed with heat sink thermal resistance. If there is no heat sink contact, θJA will almost be the same as θJC..
Recommended Operating Conditions
Symbol Characteristic Conditions Min Max Unit
Vdd Supply Voltage Operating 3.8 20 V
TA Operating Ambient Temperature Operating -40 100
°C
AH284
Document number: DS31051 Rev. 11 - 2
3 of 10
www.diodes.com
June 2010
© Diodes Incorporated
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