8983
SPINDLE & VOICE-COIL
ACTUATION MANAGER/DRIVER
8983
SPINDLE & VOICE-COIL
ACTUATION MANAGER/DRIVER
The A8983CJT provides for complete spindle and voice coil power
electronics for small form-factor HDDs (hard disk drives). The large-
scale integration and use of advanced DABiC (digital/analog-BiCMOS)
merged technologies result in minimum power dissipation, minimum
operating voltage, and minimum external components.
Data Sheet
26310.10
ABSOLUTE MAXIMUM RATINGS
at T
A
= +25
°
C
Load Supply Voltage, V
CC(PWR)
............
7.0 V
Spindle Output Current, I
OUT(S)
..........
±
1.6 A
Voice-Coil Output Current, I
OUT(A)
......
±
0.9 A
Logic Supply Voltage V
CC(D)
................
6.0 V
Operating Temperature Range,
T
A
......................................
0
°
C to +70
°
C
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.
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
—
The spindle driver system incorporates a three-phase MOS power
driver and a back-EMF sensing motor commutation scheme. A pat-
ented circuit eliminates the need for an external current-sense resistor,
achieving additional headroom. Intrinsic ground clamp and flyback
diodes are also provided.
The voice-coil system incorporates a MOS H-bridge driver, sense
amplifier, error amplifier, and programmable retract circuitry.
Dwg. PP-060
The spindle and voice-coil control functions are supplemented by
an E
NERGY
M
ANAGER
™
, which efficiently channels available spindle
BEMF to protect the heads and the data disk during system power
supply failure. Active regeneration of spindle BEMF provides nearly
lossless conversion of spindle BEMF into supply voltage to operate the
voice coil motor for parking the heads. A dc-to-dc converter provides for
full power MOS r
DS(on)
performance at minimum supply voltages. In
addition, the E
NERGY
M
ANAGER
provides several energy-saving sleep
modes and latched fault states for undervoltage and serial port com-
manded fault.
The A8983CJT is supplied in a 64-lead low-profile quad flatpack for
surface-mount applications.
FEATURES
Voice Coil Motor Driver:
s
Low r
DS(on)
MOS Outputs
s
Zero Deadband
s
Externally Determined Transconductance, with Hi/Lo
Configuration Switched via Serial Port
s
Current Sensing with External Series Sense Resistor
s
Serial Port Programmable Actuator Retract Circuitry
s
Retract Circuitry Functional to 1.7 V Spindle BEMF
Spindle Motor Controller/Driver:
s
Low r
DS(on)
MOS Outputs
s
Back-EMF Circuitry Eliminates Hall-Effect Sensors
s
Adaptive Commutation Delay Programmable via Serial Port
s
Programmable Slew Rate (soft switching) Eliminates Snubbers
s
Intrinsic Ground Clamp and Flyback Diodes
8983
SPINDLE & VOICE-COIL
ACTUATION MANAGER/DRIVER
FUNCTIONAL BLOCK DIAGRAM
ENERGY MANAGER
CONTROLLED RETRACT
DC-DC CONVERSION
SLEEP MODES
UV FAULT
+
–
+
gm
SERVO
–
+
SPIN
INPUT
INPUT
µC
SERIAL INTERFACE
SERIAL DATA IN
CLOCK
DATA ENABLE
–
g
m
SLEW
RATE
CONTROL
BACK-EMF AND
COMMUTATION LOGIC
EXTERNAL
COMMUTATION
TACH
Dwg. FP-028-1
s
Patented Lossless Current Sensing Eliminates Need
for External Current-Sense Resistor
s
Externally Determined Transconductance, with Hi/Lo
Configuration Switched via Serial Port
s
Forward or Reverse Torque Serial Port Bit Allows
Improved Speed Disturbance Performance
s
Dynamic Braking with User Delay, Activated by
Undervoltage or Serial Port Command
Energy Manager:
s
3.0 V to 5.5 V Operation
s
DC-to-DC Converter Maintains r
DS(on)
Performance
at Low Supply
s
Independent Power-Down (Sleep) Modes for all
Functional Blocks
s
Efficient Active Regeneration Supplies Power
During Retract
s
Supply Under-Voltage Fault Monitor with
Adjustable Trip Point
s
Power-On-Reset Generator for Power Up or
Power Loss with User-Defined Delay
s
Chip Powers Up in Sleep Mode for Minimum
Power Dissipation
s
External 2 MHz System Clock, or Internal Serial Port
Trimmed 2 MHz Clock
s
System Diagnostics
s
Uncommitted Op-amp
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1995, Allegro MicroSystems, Inc.
京公网安备 11010802033920号
EEWORLD
