8902鈥揂
3-PHASE BRUSHLESS DC MOTOR
CONTROLLER/DRIVER WITH BACK-EMF SENSING
LOAD
SUPPLY
C D2
C WD
C
ST
OUTA
GROUND
GROUND
OUT B
OUT C
CENTERTAP
BRAKE
C RES
1
2
V BB
COMMUTATION
DELAY
24
23
C D1
DATA IN
CLOCK
CHIP SELECT
RESET
GROUND
GROUND
DATA OUT
OSCILLATOR
LOGIC
SUPPLY
SECTOR
DATA
FILTER
Data Sheet
26301.2
SERIAL PORT
3
4
5
6
7
8
9
9
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12
BOOST
CHARGE
PUMP
22
21
20
19
18
The A8902CLBA is a three-phase brushless dc motor controller/
driver for use in 5 V or 12 V hard-disk drives. The three half-bridge
outputs are low on-resistance n-channel DMOS devices capable of
driving up to 1.25 A. The A8902CLBA provides complete, reliable,
self-contained back-EMF sensing motor startup and running algorithms.
A programmable digital frequency-locked loop speed control circuit
together with the linear current control circuitry provides precise motor
speed regulation.
A serial port allows the user to program various features and
modes of operation, such as the speed control parameters, startup
current limit, sleep mode, diagnostic modes, and others.
The A8902CLBA is fabricated in Allegro鈥檚 BCD (Bipolar CMOS
DMOS) process, an advanced mixed-signal technology that combines
bipolar, analog and digital CMOS, and DMOS power devices. The
A8902CLBA is provided in a 24-lead wide-body SOIC batwing package.
It provides for the smallest possible construction in surface-mount
applications.
MUX
FLL
VDD
17
16
15
14
13
Dwg. PP-040B
FEATURES
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
DMOS Outputs
Low r
DS(on)
Startup Commutation Circuitry
Back-EMF Commutation Circuitry
Serial Port Interface
Frequency-Locked Loop Speed Control
Sector Data Tachometer Signal Input
Programmable Start-Up Current
Diagnostics Mode
Sleep Mode
Linear Current Control
Internal Current Sensing
Dynamic Braking Through Serial Port
Power-Down Dynamic Braking
System Diagnostics Data Out
Data Out Ported in Real Time
Internal Thermal Shutdown Circuitry
ABSOLUTE MAXIMUM RATINGS
at T
A
= +25
掳
C
Load Supply Voltage, V
BB
. . . . . . . . . .
14 V
Output Current, I
OUT
. . . . . . . . . . . .
卤
1.25 A
Logic Supply Voltage, V
DD
. . . . . . . . .
6.0 V
Logic Input Voltage Range,
V
IN
. . . . . . . . . . .
-0.3 V to V
DD
+ 0.3 V
Package Power Dissipation, P
D
See Graph
Operating Temperature Range,
T
A
. . . . . . . . . . . . . . . . . .
0
掳
C to +70
掳
C
Junction Temperature, T
J
. . . . . . .
+150
掳
C鈥?/div>
Storage Temperature Range,
T
S
. . . . . . . . . . . . . . .
-55
掳
C to +150
掳
C
鈥?Fault conditions that produce excessive junction
temperature will activate device thermal shutdown
circuitry. These conditions can be tolerated, but
should be avoided.
Output current rating may be restricted to a value
determined by system concerns and factors.
These include: system duty cycle and timing,
ambient temperature, and use of any heatsinking
and/or forced cooling. For reliable operation, the
specified maximum junction temperature should
not be exceeded.
Always order by complete part number, e.g.,
A8902CLBA
.
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