Fairchild FAN8461G Single phase full wave bldc motor driver Datasheet

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FAN8461G
Single Phase Full Wave BLDC Motor Driver
Description
Features
• A wide range of operating voltage: 2.8V to 28V
• Locked rotor protection with open collector output and
auto retry
• Open collector FG output.
• Open collector Alarm output.
• TSD protection.
Typical Applications
• CPU Cooling Fans
• Instrumentation Fans
• Desktop PC Fans
The FAN8461G is a single phase BLDC motor driver and
it’s typical application is DC cooling fans with wide range of
supply voltage(3.3/5/12/24V).
Ordering Information
Device
Package
Operating Temp.
FAN8461G
10-SSOP
−30°C ~ 90°C
FAN8461GX
10-SSOP
−30°C ~ 90°C
Rev.1.0.2
©2003 Fairchild Semiconductor Corporation
FAN8461G
Block Diagram
8
7
4
6
5
VCC
VM
OUT1
OUT2
Commutation
&
Control
&
TSD
Lock
Detection
&
Auto Restart
10
AL
9
H+
2
H-
1
LD
VLDCP
GND
VLDCL
2
FG
3
FAN8461G
Pin Definitions
Pin Number
Pin Name
I/O
Pin Function Description
Remark
1
H−
A
Hall input -
2
H+
A
Hall input +
-
3
LD
A
Sawtooth wave generator for lock detector
and automatic restart
-
4
OUT1
A
Motor output 1
5
GND
P
Ground
6
OUT2
A
Motor output 2
-
7
VM
P
Motor power supply
-
8
VCC
P
Logic power supply
-
9
AL
O
Alram output
Open collector
10
FG
O
Speed output
Open collector
-
3
FAN8461G
Absolute Maximum Ratings (Ta = 25°C)
Parameter
Symbol
Maximum power supply voltage
Value
Unit
VCCMAX,VMMAX
32
V
Rja
150
oC/W
Maximum power dissipation
PDMAX
800
mW
Maximum output voltage
VOMAX
36
V
Thermal resistance
note
IOMAX
0.8
Maximum output peak current
IOPEAK
1.2note
A
Maximum FG/Alarm output current
IFG/AL
5
mA
FG/Alarm output sustain voltage
VFG/AL
36
V
Hall output withstanding voltage
VHO
36
V
Operating temperature
TOPR
−30 ~ 90
°C
Storage temperature
TSTG
−55 ~ 150
°C
Maximum output current
A
note
1 : Should not exceed PD or ASO value.
2 : IOPEAK time is within 2us.
Recommended Operating Conditions (Ta = 25°C)
Parameter
Supply voltage
Symbol
Min.
Typ.
Max.
Unit
VCC
2.8
−
28
V
Power Dissipation Curve
1.0
0.5
0
0
25
50
75
100
125
150
175
Ambient temperature, Ta [°C]
PCB condition : When mounted on 76.2mm × 114mm × 1.57mm PCB (glass epoxy material).
4
FAN8461G
Equivalent Circuits
Description
Pin No.
Internal Circuit
VCC
Hall input
1,2
1
2
VCC
LD
3
3
VM
Output
4,6
4
6
9
10
FG/AL
9 , 10
5
FAN8461G
FAN8461G Electrical Characteristics
(Ta = 25°C, VCC = 12V unless otherwise specified)
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
-
4.5
7
mA
Total
Supply current
ICC
Lock Detector & Auto Restart
LD charging current
ILDC
VLD=0V-->1.5V, VLD=1.5V
1.4
2.2
2.9
µA
LD discharging current
ILDD
VLD=3V-->1.5V, VLD=1.5V
0.15
0.33
0.50
µA
LD clamp voltage
VLDCL
-
2.3
2.6
2.9
V
LD comparator voltage
VLDCP
-
0.4
0.6
0.8
V
-
0.9
1.1
V
0.2
0.3
V
0.1
0.3
V
Output Stage
High side output saturation voltage
VOSH
IO=200mA
Low side output saturation voltage
VOSL
IO=200mA
Speed output(FG) & Lock Detection Output(AL)
FG output saturation voltage
VFGS
IFG=5mA
FG output leakage current
IFGO
VFG=12V
-
0.1
10
µA
AL output saturation voltage
VALS
IAL=5mA
-
0.1
0.3
V
IAL
VAL=12V
-
0.1
10
µA
AL output leakage current
-
Hall Amplifier
6
Input range
VHDC
-
0
-
VS-2.8
V
Input offset
VHOF
-
-10
-
10
mV
FAN8461G
Application Information
1. H-bridge motor driver(OUT1, OUT2)
Using an H-bridge to drive a single-phase BLDC motor provides several advantages for dc fans over a two phase motor commonly driven by two commutated low-side switches. A single phase motor has only two connections; hence, the H-bridge
topology requires only two output terminals and two traces are needed on the fan PCB. Generally, this H-bridge method with
single phase motor increases fan motor torque density over a typical unipolar drive method. In addition, the H-bridge topology
eliminates the number of external component for snubbing and allows recirculation of winding current to maintain energy in a
motor while switching occuers.
2. Locked Rotor Protection with Open Collector Output and Automatic Restart
When the rotor is locked, there is no change in input signal of hall amplifier and thus a internal TZERO pulse is not observed.
A capacitor(CLD) connectied LD pin is continually charged by internal current source(ILDC) to internal threshold (VLDCL)
resulting from no Tzero pulse. When the voltage,VCLD on LD pin, reaches VLDCL, high side output power TR is turned-off to
protect motor during TOFF and the alarm output (AL) becomes floating high. When the VCLD reaches upper threshold,VLDCL, VCLD starts to decrease with internal current sink(ILDD) to the low threshold, VLDCP. At that time, the VCLD
ramps up again and one of two outputs is turned on depending on locked rotor position during TON.The charging and discharging repeat until locked conditon is removed, or FAN8461G is powerd down. The overall time chart is shown in figure.1.
The auto- retry time(TON), the motor protection time(TOFF), the locked rotor detection time(TLOCK) are proportional to
external capacitor, CLD and each value can be calculated as follows;
T
C
× (V
–V
)
LD
LDCL
LDCP = ---------------------------------------------------------------------ON
I
LDC
T
C
× (V
–V
)
LD
LDCL
LDCP = ---------------------------------------------------------------------I
LDD
OFF
T
C
× VLDCL
LD
-------------------------≅
LOCK
I
LDC
For example, CLD = 0.33uF, then TON= 0.3Sec,TOFF= 2Sec,TLOCK= 0.4Sec. This AL output can be used to inform a locked
rotor condition to super IO or system controller. Because the AL output is open collector type, end user can pull up this pin
with a external resistor to the supply voltage of their choice(that is 5 or 3.3V). It is recommednd that this AL output be higher
than the GND potential.
7
FAN8461G
Rotor
HH+
NSNSNSN
N
TOFF
SNSNSNS
TON
VLDCL
VLDCP
LD
Tzero
OUT2
OUT1
Tlock
AL
FG
1 rotation
Motor
Locked
Lock
Released
Figure 1. Overall Timing Chart
8
FAN8461G
3. Hall Sensor Amplifier
V+
RH
CH1
IN+
2
CH2
FAN8461G
Ri
Hall
Sensor
1
IN-
Figure 2. Hall Sensor Interface
The hall current (IH) is determined as follows;
I
H
V CC
= -------------------------(RH + Ri)
Where, RH is an external limiting resistor and Ri is input impedance of hall sensor. An external capacitor, CH1, can be used to
reduce a power supply noise.CH2 can reduce the instant peak current using H-bridge’s commutation. The input range of hall
amplifier is between 0V and VCC-2.8V as shown in following figure.
VS
V S - 2 .8 V
VS / 2
GND
Figure 3. Hall Amplifier Input Range
Table 1. Hall Sensor Outputs and Related Pin outputs
H+
H-
LD
OUT 1
OUT 2
AL
TACO
H
L
Low Level
L
H
L
L
L
H
Low Level
H
L
L
H
ROTATING
-
-
-
H
L or H
LOCK
-
Remark
8. Open Collector FG Output for Speed Feedback
The FG output comes from the hall amplifier output. Because the FG output is open collector type, end user can pull up this
pin with a external resistor to the supply voltage of their choice(that is 5 or 3.3V). This resulting output signal has two pulses
per revolution on a four pole motor. It is recommednd that this FG output be higher than the GND potential.
9. Supply Voltage Consideration
A supply sustain capacitor(CR) should be placed as close to VCC pin with GND as layout permits. A reverse supply protection
diode(DR) prevent motor current from recirculating to power source when phase commutation occur. This results in increasing
VCC pin voltage. This capacitor absorbs motor recirculating current and limits VCC pin voltage. In general, large motor winding induactance and current need large value of CR.
10. Thermal Shutdown
TSD on: Two high side outputs are off.(Typ. 175°C)
TSD off:The circuit can be reactivated and begin to operate in a normal condition. (Typ. 150°C)
9
FAN8461G
Typical Application Circuits 1
8
V+
7
VCC
VM
CR
6
5
OUT1
OUT2
Lock
Detection
&
Auto Restart
AL
9
H+
2
H-
1
LD
VLDCP
GND
VLDCL
10
10
3
V+
Hall
Sensor
4
Commutation
&
Control
&
TSD
FG
FAN8461G
Package Dimensions (Unit: mm)
11
FAN8461G
Typical Performance characreristics
Low side TR saturation voltage
High side TR saturation voltage
VCC current consumption
2.5
5
VCE[V]
ICC[mA]
2.0
4
VS=VM=12V
1.5
1.0
0.5
3
0
5
10
15
VCC[V]
12
20
25
30
0.0
0.0
0.1
0.2
0.3
0.4
Motor current[A]
0.5
0.6
0.7
FAN8461G
13
FAN8461G
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.
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.
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