8902–A
3-PHASE BRUSHLESS DC MOTOR
CONTROLLER/DRIVER WITH BACK-EMF SENSING
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
LOAD
SUPPLY
COMMUTATION
DELAY
1
24
23
C
V
D1
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.
BB
DATA IN
C
2
3
4
D2
22 CLOCK
21
C
WD
C
CHIP SELECT
ST
20 RESET
OUT
5
6
A
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.
19
18
GROUND
GROUND
GROUND
GROUND
7
8
OUT
B
DATA OUT
OSCILLATOR
MUX
17
16
15
The A8902CLBA is fabricated in Allegro’s 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.
9
9
OUT
C
FLL
V
LOGIC
SUPPLY
CENTERTAP 10
DD
BOOST
CHARGE
PUMP
SECTOR
DATA
14
BRAKE
11
12
C
13 FILTER
RES
Dwg. PP-040B
FEATURES
■ DMOS Outputs
ABSOLUTE MAXIMUM RATINGS
at TA = +25°C
■ Low rDS(on)
■ Startup Commutation Circuitry
■ Back-EMF Commutation Circuitry
■ Serial Port Interface
Load Supply Voltage, VBB . . . . . . . . . . 14 V
Output Current, IOUT . . . . . . . . . . . . ±1.25 A
Logic Supply Voltage, VDD . . . . . . . . . 6.0 V
Logic Input Voltage Range,
VIN . . . . . . . . . . . -0.3 V to VDD + 0.3 V
Package Power Dissipation, PD See Graph
Operating Temperature Range,
TA . . . . . . . . . . . . . . . . . . 0°C to +70°C
Junction Temperature, TJ . . . . . . . +150°C†
Storage Temperature Range,
■ Frequency-Locked Loop Speed Control
■ Sector Data Tachometer Signal Input
■ Programmable Start-Up Current
■ Diagnostics Mode
■ Sleep Mode
■ Linear Current Control
TS . . . . . . . . . . . . . . . -55°C to +150°C
■ 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
† 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 .