Datasheet FAN8408D Datasheet (Fairchild Semiconductor)

FAN8408D

2 Phase Half Wave BLDC Motor Driver

www.fairchildsemi.com

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

©2002 Fairchild Semiconductor Corporation

Ordering Information

Device Package Operating Temp.

FAN8408D 8-SOP-225 −25°C ~ 85°C

FAN8408DTF 8-SOP-225 −25°C ~ 85°C

Rev.1.0.4

FAN8408D

Block Diagram

OUT

OUT

LD

1

B

3

HO

2

Commutation &

Control

7

A

& TSD

V

GND

CC

4

IN+

8

5

IN-

6

Pin Definitions

Pin Number Pin Name I/O Pin Function Description Remark

1OUT

B

2 HO O Hall output Open Collector
3LD­4V

CC

5IN+ I Hall input + -
6IN− I Hall input − -
7OUT

A

8 GND - Ground -

O Motor output B -

Triangle pulse generator for lock detector
and automatic restart

- Supply voltage -

O Motor output A -

-

2

Equivalent Circuits

Description Pin No. Internal Circuit

OUT

B

1

FAN8408D

OUT

A

HO

LD 3

7

1
7

Commutation

2

2

Commutation

3

Lock detector

& Automatic

restart

Commutation

IN+ 5

IN- 6

V

LDCP

V

LDCL

5
6

Commutation

3

FAN8408D

Absolute Maximum Ratings (Ta = 25°C)

Parameter Symbol Value Unit

Maximum power supply voltage V
Maximum power dissipation

Thermal resistance

note1

note1

Maximum output voltage V
Maximum output current I
Hall output current I
Hall output withstanding voltage V
Maximum hall input ac level V
Operating temperature T
Storage temperature T

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

or ASO value

D

CCMAX

P

DMAX

Θ

JA

OMAX

OMAX

HO

HO

HACMAX

OPR

STG

18 V

note2

429
620

291.61

201.52

note3

note2
note3

mW

°C/W

30 V

note4

1.2

A
10 mA
36 V

6V

−25 ~ 85 °C

−55 ~ 150 °C

Power Dissipation Curve (Air condition = 0m/s)

0.5

0.45

0.4

0.35

0.3

0.25

Pd[W]

0.2

0.15

0.1

0.05
0

0 20 40 60 80 100 120 140 160

Tc or Ta[°C]

4

FAN8408D

Air Speed & Θ

JA

350
300
250
200
150

JA[°C/W]

100

50

0

0123456

Air Speed[m/s]

Recommended Operating Conditions (Ta = 25°C)

Parameter Symbol Min. Typ. Max. Unit

Function compensation operating voltage V

CC

4.0 − 15.0 V

Electrical Characteristics

(Ta=25°C, VCC=12V unless otherwise specified)

Parameter Symbol Conditions Min. Typ. Max. Unit

Supply current I
Lock detector charging current I
Lock detector discharging current I
Lock detector charging/discharging ratio R
Lock detector capacitor clamp voltage V
Lock detector capacitor comparator voltage V
Output low level voltage V
Output leakage current I
Output zener voltage V
Hall output pin low level voltage V
Hall output pin leakage current I

Hall input dc range V
Hall input offset V

CC
LDC
LDD

CD

LDCL

LDCP

OL

OL

OZ

HLL

HLL
HDC

HOF

When output is off. - - 3.0 mA
VLD=1.8V 2.38 3.40 4.42 µA
VLD=1.8V 0.48 0.68 0.88 µA
RCD=I

LDC/ILDD

3.0 5.0 7.0 −

- 2.4 2.85 3.3 V

- 0.7 0.99 1.2 V

IO=200mA - 0.9 1.2 V

--010µA
Clamp current=10mA 28 30 32 V
IO=10mA - 0.2 0.5 V

--010µA

-

V

-1-

V

=6V -10 - 10 mV

REF

CC

2V

V

5

FAN8408D

Application Information

1. Lock Detection & Automatic Restart

Hall Input

Output

V

LDCL

V

LDCP

Motor lock

detected

Motor lock

T

OFF

T

ON

Motor lock

cleared

Motor restart

FAN8408D features a lock detection and an automatic restart. The functions can be operated as follow s.

1) When the hall signal stop switching, a motor can be locked.

2) The voltage, V

on pin 3, is increasing until it reaches V

LD

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.

T

T

ON

OFF

C

LDVLDCLVLDCP

------------------------------------------------------------------------ -=

C

LDVLDCLVLDCP

------------------------------------------------------------------------ -=

I

LDC

I

LDD

–()×

–()×

Where, The C
The V

LDCL

The V

LDCP

The I

LDC

The I

LDD

is an external capacitor connected to pin 3, LD.

LD

is the clamp voltage on pin 3, LD.

is the comparator voltage on pin 3, LD.
is the charging current on pin 3, LD.
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)

6

3. Hall Amplifier Input Block

FAN8408D

V

CC

R1

FAN8408D

The hall current (IH) is determined by R1, R2 and R3.

V

I

H

CC

----------------------------------- -=

R1 R2 R3++

IN+

C1

5

C2

6

IN-

R2

Hall

Sensor

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

V

CC

-2V as following figure.

CC

VCC-2V

/ 2

V

CC

1V

GND

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.

7

FAN8408D

Operation Truth Ta ble

IN+ IN- OUT

A

OUT

B

High Low High Low Low

Low High Low High High

Test Circuits

V

CC

1K

50

OUT

1

2

B

HO

GND

OUT

HO

A

50

8

7

I

LDC

/ I

A

LDD

V

LD

3

LD

4

V

CC

IN-

IN+

6

5

A

I

CC

V

CC

8

Typical Application Circuits

1

OUT

B

7

OUT

A

V

CC

4

8

GND

Commutation &

Control

& TSD

FAN8408D

LD

3

2

HO

V

CC

IN+

5

Hall

6

IN-

Precaution

In case of improper connection (change between power and ground), diode is required to protect motor.

9

FAN8408D

Package Dimensions (Unit: mm)

8-SOP-225

10

FAN8408D

11

FAN8408D

DISCLAIMER

FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHE R NOTICE TO ANY
PRODUCTS HEREI N TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHIL D DOES NOT ASSUME AN Y
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.

LIFE SUPPORT POL I CY

FAIRCHILD’S PRODUCTS ARE NOT AUTH ORIZED FOR USE AS CRI TICAL 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

2. A critical component in any component of a life support
device or system whose fa ilure to perform can be
reasonably expec ted to cause the failur e of the life support
device or system, or to affect its safety or effec t iv ene ss .

instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of the
user.

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10/17/02 0.0m 001

 2002 Fairchild Semiconductor Corporation

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