NOT RECOMMENDED FOR NEW DESIGN
USE
AH2985
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 SIP-4 and SOT89-5 packages.
Pin Assignments
(Top View)
284
1 : Vdd
2 : DO
3 : DOB
4 : GND
1 2 3 4
GND
Vdd
(Top View)
1
2
284
7
DOB
4
SOT89-5
5
NC
OBSOLETE – PART DISCONTINUED
DO
3
SIP-4
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-4 and SOT89-5
Green Molding Compound
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Applications
•
•
Two-coil BLDC Cooling Fans
Low to Medium Voltage, Low Power BLDC Motors
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.
AH284
Document number: DS31051 Rev. 12 - 3
1 of 11
www.diodes.com
June 2017
© Diodes Incorporated
NOT RECOMMENDED FOR NEW DESIGN
USE
AH2985
AH284
Typical Application Circuit
(Note 4)
12V
V
dd
D2
D1
OBSOLETE – PART DISCONTINUED
284
L2
L1
1
2
3
4
GND
D3
C3
DOB
DO
R1
C1
R2
C2
Note:
4. Typically it is recommended to us a 56 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.
Pin Descriptions
Pin Name
(SOT89-5)
Description
Input Power
Output Pin
Output Pin
Ground
Not Connected
Vdd
DO
DOB
GND
NC
AH284
Document number: DS31051 Rev. 12 - 3
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June 2017
© Diodes Incorporated
NOT RECOMMENDED FOR NEW DESIGN
USE
AH2985
AH284
Functional Block Diagram
Vdd
OBSOLETE – PART DISCONTINUED
Lock detect,
shutdown and
automatic re-start
Regulator
DO
Hall
Plate
Amp.
Control Logic
DOB
GND
AH284
Document number: DS31051 Rev. 12 - 3
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June 2017
© Diodes Incorporated
NOT RECOMMENDED FOR NEW DESIGN
USE
AH2985
AH284
Absolute Maximum Ratings
(T
A
= +25°
C)
Symbol
V
DD
Supply Voltage
Output Current
I
O(AVE)
I
O(PEAK)
P
D
T
ST
T
J
θ
JA
Power Dissipation
Storage Temperature
Maximum Junction Temperature
Thermal Resistance Junction to Case
(Note 5)
SIP-4
SOT89-5
SIP-4
SOT89-5
SIP-4
SOT89-5
Characteristics
Rating
24
500
500
700
550
800
-55 to +150
+150
227
156
Unit
V
mA
mA
mA
mW
mW
C
C
C/W
C/W
OBSOLETE – PART DISCONTINUED
I
O
T
A
T
J
Tc
JA
JC
Note:
5. θ
JA
should be confirmed with heat sink thermal resistance. If there is no heat sink contact, θ
JA
will almost be the same as θ
JC
.
Recommended Operating Conditions
Symbol
V
DD
T
A
Supply Voltage
Operating Ambient Temperature
Characteristic
Conditions
Operating
Operating
Min
3.8
-40
Max
20
+100
Unit
V
C
AH284
Document number: DS31051 Rev. 12 - 3
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June 2017
© Diodes Incorporated
NOT RECOMMENDED FOR NEW DESIGN
USE
AH2985
AH284
Electrical Characteristics
(T
A
= +25° V
DD
= 12V, unless otherwise specified.)
C,
Symbol
I
DD
Supply Current
Output Leakage Current
Rotor Lock Protection On Time
Rotor Lock Protection Off Time
Output Saturation Voltage
Output On Resistance
Output Zener-Breakdown Voltage
Characteristics
Conditions
Operating
V
OUT
= 24V
-
-
I
O
= 300mA
I
O
= 500mA
I
O
= 300mA
-
Min
-
-
0.4
2.4
-
-
-
35
Typ.
2.0
< 0.1
0.5
3
375
625
1.25
42
Max
4.0
10
0.6
3.6
500
mV
900
1.67
60
V
Unit
mA
μA
Sec
Sec
OBSOLETE – PART DISCONTINUED
I
OFF
t
RLP-ON
t
RLP-OFF
V
OUT(SAT)
R
DS(ON)
V
Z
Truth Table
IN-
H
L
-
IN+
L
H
-
CT
L
L
H
OUT1
H
L
Off
OUT2
L
H
Off
Mode
Rotating
Rotating
Lockup protection activated
Magnetic Characteristics
(T
A
= +25° V
DD
= 12V, unless otherwise specified, Note 6)
C,
(1mT = 10 Gauss)
Symbol
Bop
Brp
Bhy
Note:
Operation Point
Release Point
Hysteresis
Characteristics
Min
10
-60
-
Typ.
30
-30
60
Max
60
-10
-
Unit
Gauss
Gauss
Gauss
6. The magnetic characteristics may vary with supply voltage, operating temperature and after soldering.
AH284
Document number: DS31051 Rev. 12 - 3
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June 2017
© Diodes Incorporated
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