8905
3-PHASE BRUSHLESS DC
MOTOR CONTROLLER/DRIVER
8905
Data Sheet
26301.3
3-PHASE BRUSHLESS DC MOTOR
CONTROLLER/DRIVER WITH BACK-EMF SENSING
The A8905CLB isw a three-phase brushless dc motor controller/
driver for use with CD-ROM or DVD drives. The three half-bridge
outputs are low on-resistance n-channel DMOS devices capable of
driving up to 1.25 A. The A8905CLB 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.
LOAD
SUPPLY
C D2
C WD
CST
1
2
V BB
COMMUTATION
DELAY
24
23
C D1
DATA IN
CLOCK
CHIP SELECT
RESET
SERIAL PORT
3
4
5
6
7
22
21
20
19
OUTA
GROUND
GROUND
OUT B
OUT C
CENTERTAP
BRAKE
C RES
ABSOLUTE MAXIMUM RATINGS
at T
A
= +25
°
C
Load Supply Voltage, V
BB
. . . . . .
14 V
Output Current, I
OUT
. . . . . . . .
±
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
°
C to +70
°
C
Junction Temperature, T
J
. . .
+150
°
C†
Storage Temperature Range,
T
S
. . . . . . . . . . . .
-55
°
C to +150
°
C
† 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.
T
C
U Y
D L
O N
R O
P E
D C
E N
U E
IN ER
T F
N E
O R
C R
IS O
D F
—
GROUND
18
GROUND
8
MUX
FLL
17
DATA OUT
9
9
16
OSCILLATOR
APPLICATIONS
s
CD-ROMs
s
DVDs
10
11
VDD
15
14
LOGIC
SUPPLY
INDEX
BOOST
CHARGE
PUMP
12
13
FILTER
FEATURES
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
Dwg. PP-040-1
DMOS Outputs
Low r
DS(on)
Startup Commutation Circuitry
Back-EMF Commutation Circuitry
Serial Port Interface
Frequency-Locked Loop Speed Control
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
Always order by complete part number, e.g.,
A8905CLB
.
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