Diodes AH291 User Manual
AH291
LOW VOLTAGE HALL-EFFECT SMART FAN MOTOR
CONTROLLER
Description
AH291 is a monolithic fan motor controller with Hall sensor’s
capability. It contains two complementary open-collector
drivers for motor’s coil driving, automatic lock shutdown and
restart function relatively.
Rotor-lock shutdown detection circuit turns off the output
driver when the rotor is blocked to avoid coil overheat. T hen,
the automatic recovery circuit will restart the motor. These
protected actions are repeated and periodic during the
blocked period. Until the blocking is removed, the motor
recovers and runs normally.
The AH291 is available in SIP4 and SOT89-5L packages.
Features
• On Chip Hall Sensor
• Rotor-Locked Shutdown
• Automatically Restart
• Built-in Zener Protection for Output Driver
• Operating Voltage: 1.8V to 5.75V
• Output Current: I
• Packages: SIP-4L and SOT89-5L
• Green Molding Compound
O(AVE)
= 400mA
Pin Assignments
(Top View)
291
12 43
SIP-4L
1 : Vdd
2 : DO
3 : DOB
4 : GND
Vdd
GND
(Top View)
1
291
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)
1.8V/5.75V
Notes: 1. R1, R2: typical 56 Ohm
C1, C2, C3: typical 2.2µF
The R, C value need to be fine tuned based on coils design.
AH291
Document number: DS31041 Rev. 8 - 2
V
dd
D1
C3
1.8V/5.75V Brush-Less DC Fan
D2
291
1234
DO
1 of 9
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GND
DOB
L2 L1
R1 R2
C1 C2
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
AH291
LOW VOLTAGE HALL-EFFECT SMART FAN MOTOR
CONTROLLER
Regulator
Hall
Plate
AH291
Document number: DS31041 Rev. 8 - 2
Amp.
Lock detect,
shutdown and
automatic re-start
Control Logic
GND
2 of 9
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DO
DOB
June 2010
© Diodes Incorporated
AH291
LOW VOLTAGE HALL-EFFECT SMART FAN MOTOR
CONTROLLER
Absolute Maximum Ratings (T
Symbol Characteristics Rating Unit
Vdd Operating Supply Voltage 8 V
IO Output Current
PD Power Dissipation
TST Storage Temperature -55 ~ 150
TJ Maximum Junction Temperature 150
Recommended Operating Conditions
Symbol Characteristic Conditions Min Max Unit
Vdd Supply Voltage (Note 2) Operating 1.8 5.75 V
TA Operating Ambient Temperature Operating -20 100
Notes: 2. The output of IC will be switched after the supply voltage is over 1.8V, but the magnetic characteristics won't be normal until the
supply is over 2.0V.
= 25°C)
A
O(AVE)
I
O(PEAK)
SOT89-5L 400 mA
700 mA
SIP-4L 400 mA
I
SIP-4L 550 mW
SOT89-5L 800 mW
°C
°C
°C
Electrical Characteristics (T
= 25 °C, Vdd = 5V, unless otherwise specified)
A
Symbol Characteristics Conditions Min Typ. Max Unit
Idd Supply Current Operating - 2.6 4.0 mA
T
T
RLP-OFF
V
R
RLP-ON
DS(ON)
Rotor Lock Protection On Time - 0.4 - Sec
Rotor Lock Protection Off Time 2.4 3 3.6 Sec
I
= 180mA - 300 - mV
Output Saturation Voltage
)SAT(OUT
O
IO = 350mA - 600 - mV
Output On Resistance - 1.75 - ohm
Vz Output Zener-Breakdown Voltage - 15 - V
Truth Table
IN- IN+ CT OUT1 OUT2 Mode
H L L H L Rotating
L H L L H Rotating
- - H off off Lockup protection activated
AH291
Document number: DS31041 Rev. 8 - 2
3 of 9
www.diodes.com
June 2010
© Diodes Incorporated
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