2002 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev.1.0.4
Features
A wide range of operation voltage: 4V to 15V
Built-in motor lock detector.
Automatic restart function
Hall output for a motor speed detection
Built-in thermal shut down circuits
Built-in reverse current protection diode
Compact package: 8-SOP-225
Description
The FAN8408D is a monolithic integrated circuit, and
suitable for DC cooling fan motors.
8-SOP-225
1
Typical Applications
DC cooling fan motor
Ordering Information
Device
Package
Operating Temp.
FAN8408D
8-SOP-225
-
25
C ~ 85
C
FAN8408DTF
8-SOP-225
-
25
C ~ 85
C
FAN8408D
2 Phase Half Wave BLDC Motor Driver
FAN8408D
2
Block Diagram
Pin Definitions
Pin Number
Pin Name
I/O
Pin Function Description
Remark
1
OUT
B
O
Motor output B
-
2
HO
O
Hall output
Open Collector
3
LD
-
Triangle pulse generator for lock detector
and automatic restart
-
4
V
CC
-
Supply voltage
-
5
IN
+
I
Hall input +
-
6
IN
-
I
Hall input
-
-
7
OUT
A
O
Motor output A
-
8
GND
-
Ground
-
OUT
B
OUT
A
V
CC
GND
IN-
IN+
HO
LD
1
7
Commutation &
Control
& TSD
3
2
6
5
8
4
FAN8408D
3
Equivalent Circuits
Description
Pin No.
Internal Circuit
OUT
B
1
OUT
A
7
HO
2
LD
3
IN+
5
IN-
6
1
7
Commutation
Commutation
2
3
Lock detector
& Automatic
restart
Commutation
V
LDCP
V
LDCL
5
6
Commutation
FAN8408D
4
Absolute Maximum Ratings (Ta = 25
C)
Note1:
PCB Condition: Thickness(1.6mm), Dimension(76.2mm * 114.3mm)
Refer: EIA/J SED 51-3 & EIA/J SED 51-7
Note2: Air condition (0m/s)
Note3: Air condition (3m/s)
Note4: Should not exceed P
D
or ASO value
Power Dissipation Curve (Air condition = 0m/s)
Parameter
Symbol
Value
Unit
Maximum power supply voltage
V
CCMAX
18
V
Maximum power dissipation
note1
P
DMAX
429
note2
mW
620
note3
Thermal resistance
note1
JA
291.61
note2
C/W
201.52
note3
Maximum output voltage
V
OMAX
30
V
Maximum output current
I
OMAX
1.2
note4
A
Hall output current
I
HO
10
mA
Hall output withstanding voltage
V
HO
36
V
Maximum hall input ac level
V
HACMAX
6
V
Operating temperature
T
OPR
-
25 ~ 85
C
Storage temperature
T
STG
-
55 ~ 150
C
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0
20
40
60
80
100
120
140
160
Tc or Ta[C]
Pd
[W]
FAN8408D
5
Air Speed &
JA
Recommended Operating Conditions
(Ta = 25
C)
Electrical Characteristics
(Ta=25
C, V
CC
=12V unless otherwise specified)
Parameter
Symbol
Min.
Typ.
Max.
Unit
Function compensation operating voltage
V
CC
4.0
-
15.0
V
Parameter
Symbol
Conditions
Min.
Typ.
Max. Unit
Supply current
I
CC
When output is off.
-
-
3.0
mA
Lock detector charging current
I
LDC
V
LD
=1.8V
2.38
3.40
4.42
A
Lock detector discharging current
I
LDD
V
LD
=1.8V
0.48
0.68
0.88
A
Lock detector charging/discharging ratio
R
CD
R
CD
=I
LDC
/I
LDD
3.0
5.0
7.0
-
Lock detector capacitor clamp voltage
V
LDCL
-
2.4
2.85
3.3
V
Lock detector capacitor comparator voltage
V
LDCP
-
0.7
0.99
1.2
V
Output low level voltage
V
OL
I
O
=200mA
-
0.9
1.2
V
Output leakage current
I
OL
-
-
0
10
A
Output zener voltage
V
OZ
Clamp current=10mA
28
30
32
V
Hall output pin low level voltage
V
HLL
I
O
=10mA
-
0.2
0.5
V
Hall output pin leakage current
I
HLL
-
-
0
10
A
Hall input dc range
V
HDC
-
1
-
V
CC
-
2V
V
Hall input offset
V
HOF
V
REF
=6V
-10
-
10
mV
0
50
100
150
200
250
300
350
0
1
2
3
4
5
6
Air Speed[m/s]
JA
[
C
/
W
]
FAN8408D
6
Application Information
1. Lock Detection & Automatic Restart
FAN8408D features a lock detection and an automatic restart. The functions can be operated as follows.
1) When the hall signal stop switching, a motor can be locked.
2) The voltage, V
LD
on pin 3, is increasing until it reaches V
LDCL
.
3) If LD pin is connected to GND, the lockup protection is disabled.
4) While a motor is locked, the output repeats switching ON / OFF, but the other output is always OFF. The switching time can
be determined by an external capacitor on charging / discharging time of the capacitor, switching ON / OFF time can be
calculated as follows.
Where, The C
LD
is an external capacitor connected to pin 3, LD.
The V
LDCL
is the clamp voltage on pin 3, LD.
The V
LDCP
is the comparator voltage on pin 3, LD.
The I
LDC
is the charging current on pin 3, LD.
The I
LDD
is the dischaging current on pin 3, LD.
2. Thermal Shut Down
TSD On: All the outputs are off.(Typ. 175
C)
TSD Off: The circuit can be reactivated and begin to operate in a normal condition. (Typ. 150
C)
T
OFF
T
ON
Hall Input
Output
V
LDCL
V
LDCP
Motor lock
detected
Motor lock
cleared
Motor lock
Motor restart
TON
CLD VLDCL VLDCP
(
)
ILDC
-------------------------------------------------------------------------
=
TOFF
CLD VLDCL VLDCP
(
)
ILDD
-------------------------------------------------------------------------
=
FAN8408D
7
3. Hall Amplifier Input Block
The hall current (I
H
) is determined by R1, R2 and R3.
Where, the R2 is the impedance of hall sensor.
An external capacitor, C1, can be used to reduce a power supply noise. In addition, C2 is to remove a noise which is caused in
case the line is long from the hall sensor output to the hall input (pin 5 / 6) of the device.
The input bias voltage of hall amplifier is between 1V and V
CC
-2V as following figure.
It is recommended that R1 and R3 should have the same value to make the output signal of hall sensor centered as V
CC
/2.
FAN8408D
IN-
IN+
6
5
V
CC
Hall
Sensor
C2
C1
R1
R2
R3
IH
VCC
R1 R2 R3
+
+
------------------------------------
=
V
CC
V
CC
-2V
V
CC
/ 2
1V
GND
FAN8408D
8
Operation Truth Table
Test Circuits
IN+
IN-
OUT
A
OUT
B
HO
High
Low
High
Low
Low
Low
High
Low
High
High
1
2
3
4
8
7
6
5
A
A
I
CC
V
CC
V
CC
I
LDC
/ I
LDD
V
LD
50
1K
50
OUT
B
HO
LD
V
CC
IN+
IN-
OUT
A
GND
FAN8408D
9
Typical Application Circuits
Precaution
In case of improper connection (change between power and ground), diode is required to protect motor.
V
CC
OUT
B
OUT
A
V
CC
GND
IN-
IN+
HO
LD
Hall
1
7
3
2
6
5
8
4
Commutation &
Control
& TSD
FAN8408D
10
Package Dimensions (Unit: mm)
8-SOP-225
FAN8408D
11
FAN8408D
10/17/02 0.0m 001
Stock#DSxxxxxxxx
2002 Fairchild Semiconductor Corporation
LIFE SUPPORT POLICY
FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body,
or (b) support or sustain life, and (c) whose failure to
perform when properly used in accordance with
instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of the
user.
2. A critical component in any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
www.fairchildsemi.com
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY
PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER
DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
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