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FAN8621B
12V Spindle Motor and Voice Coil Motor Driver IC
Features
General
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•
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Hysteresis power on reset with delay function
5V, 12V supplies monitoring
Thermal shut down(TSD)
Programmable precision regulator usging minimal
external component
• Three state control input to reduce number of PINs
Description
The FAN8621B, is a Bipolar monolithic stand-alone IC,
designed for 12V HDD applications.The internal power
stage consists of vertical PNP and NPN TRs for both SPM
and VCM, thus minimizing voltage drop, and increasing
drive capability up to 2A for SPM and 1.2A for VCM. This
device includes soft commutation drive to reduce audible
noise and intelligent retract function for decreased bouncing.
Spindle Motor(SPM)
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•
•
•
•
•
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•
•
•
•
ASIC based start-up
Internal back-EMF processing
Internal sensorless commutation
Internal SPM speed control with SFLL(Syncronized
Frequency Lock Loop).
Linear SPM current control
Selectable Motor Speed (5400/7200 RPM)
Soft commutation circuitry to reduce acoustic noise
Adjustable brake delay time
Maximum 2A start-up current capability
Internal and external spindle brake
Speed lock indicator output
48-QFPH-1414
Voice Coil Motor (VCM)
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•
•
•
•
Intelligent retract (decreased bouncing)
1.2A internal VCM power driver
Selectable transconductance
4V precision reference output
Two PWM input (fine/coarse) for VCM set point
Typical Applications
• Hard disk drive(HDD)
Ordering Information
Device
FAN8621B
Package
48-QFPH-1414
Operating Temp.
0 ~ 70°C
Rev. 1.0.0
May. 2000.
©2000 Fairchild Semiconductor International
1
FAN8621B
Pin Assignments
B
2
FAN8621B
Pin Definitions
Pin Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
Pin Name
VCNT
CSOFT
ADJ
SENSE5
VDD
FG
VREF
CLK
HALFVCC
POR
CDLY
GAINSEL
PWMH
PWML
CFVCM
VCMREF4V
CRET
VCC
FILOUT
SENSE
CRET2
PVCC
VCM-
RRET
SENSEOUT
PGND
VCM+
ERRIN
VDD
ERROUT
SUBGND
W
IO
A
A
A
A
P
O
P
I
P
O
A
I
I
I
A
P
A
P
A
A
A
P
A
A
A
P
A
A
P
A
P
A
Pin Function Description
Speed controller output. Range 3.8V to 0.5V
Capacitor for soft commutation
Adjust external regulator voltage (VREF)
5V power line sensing
5V power line
Frequency generation for spindle rotation speed. Typically
1.08KHz (5400RPM)
Regulator voltage output. This voltage is controlled by pin 3
voltage
System clock. Digital clock input as a time reference
1/2 VCC
Power on reset. H : normal, L: power fail
Define POR delay time
Sense amplifier gain selection. H : High gain (8), L : Low gain (2)
Coarse PWM input for VCM set point
Fine PWM input for VCM set point
Output of PWM inputs to voltage converter
4V reference output for VCM
Define retract delay time.
12V power line
Filtered output of PWM inputs. This voltage define VCM set point
Non-inverting input of differential amplifier for VCM current
sensing
Power for retract when power down
12V power line for VCM
Negative output terminal of VCM power amplifier
Adjust maximum retract current
Output of differential amplifier for VCM current sensing
Ground for VCM
positive output terminal of VCM power amplifier
Inverting input of VCM error amplifier
5V power line
Output of VCM error amplifier
Ground for spindle motor
Spindle W phase output
3
FAN8621B
Pin Definitions (Continued)
Pin Number
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
Pin Name
PCS
V
SUBGND
N
U
PVCC
CCOMP
BRAKE
CBRAKE
SENSE12
GND
CNTL1
CNTL2
CNTL3
READY
RPMSEL
IO
A
A
P
A
A
P
A
A
A
A
P
I
I
I
O
I
Pin Function Description
Spindle current sensing.
Spindle V phase output
Ground for spindle
Spindle N phase output
Spindle U phase output
12V power line for spindle
Current controller output. This Voltage define spindle output
current
Gating signal for external brake
Charged back-EMF to supply brake power when power down
12V power line sensing
Ground
Control input for spindle . H: spindle enable, Z: Spindle bias
enable, L: brake
Start-up clock and soft commutation. H: Start-up clock , L : soft
commutation.
Control input for VCM. H: VCM enable, Z : VCM disable, L:
retract
Speed lock indicator when speed is within 0.7% speed error
range. H : speed locked, L: unlocked
Target spindle speed selection. L : 5400 rpm, H: 7200 rpm with
5MHz Clock
4
FAN8621B
Internal Block Diagram
CDLY
11
VCC
25K
POR
10
TSD
VREF
7
ADJ
3
VDD VDD VCC
5
29
18
VDD
7K
SENSE12
SENSE5
42
4
9K
11K
Power
Management
Bandgap
Reference
&
Bias
1.3V
Retract
External
Brake
40
41
U
V
W
N
38
BRAKE
CBRAKE
U
FG
6
FG
Generator
CSOFT
2
clock
Triangle Wave
Generator
Back-EMF
Processing
&
Zero Cross Detector
SPM
Three Phase
Power Driver
PVCC
36
37
Commutation
Sequencing
&
Spindle Control
34
32
35
pre
amp
31
N
U
V
W
SUBGND
SUBGND
CCOMP
PCS
PVCC
VCM+
SPM bias enable
CNTL1
CNTL2
CNTL3
44
45
46
VCM
on/off
Retract
Three State
Input
Control
SPM output on
start-up clock
hard/soft
Brake
VDD
FG
Real
Speed
i
spll
READY
RPMSEL
47
48
Speed
Discriminator
&
Speed Lock
Indicator
Current
Limiting
39
33
VCM
H-bridge
Power Driver
VCMREF4V
power
amp
VCC
error
amp
clock
22
Speed
Reference
i
spll
VCNT
27
1
CLK
8
Counter
&
Timing Control
9
power
amp
gain
14
26
HALFVCC
PWMH
PWML
CFVCM
GAINSEL
13
14
15
12
PWMs
Decorder
&
2nd orderFilter
23
VCM-
PGND
U
V
W
Retract
VCMREF4V
sense
amp
gain
2,8
VCM
Gain Selection
Intelligent
Retract
VCM+
SENSE
20
SENSE
VCMREF4V
16
VCMREF4V
43
21
24
17
19
28
30
25
GND
CRET2 RRET CRET FILOUT ERRIN
ERROUT
SENSEOUT
5
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