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Allegro MicroSystems

A8980CJT Datasheet Preview

A8980CJT Datasheet

SUPERSERVO SPINDLE & VOICE-COIL ACTUATION MANAGER/DRIVER

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8980
SUPERSERVO
8980SPINDLE & VOICE-COIL
ACTUATION MANAGER/DRIVER
TM
SUPERSERVO SPINDLE & VOICE-COIL
ACTUATION MANAGER/DRIVER
BACK-EMF and
COMMUTATION LOGIC
8
SPIN-DEMAND
The A8980CJT provides complete drive, management, and control
of the voice-coil and spindle motor power actuation subsystems used
in hard disk drives. Extensive programmable control features and
system diagnostics are provided via a serial interface under the
direction of an external microcontroller. The large-scale integration
and use of advanced DABiC(digital/analog-BiCMOS) merged
technologies results in minimum power dissipation, minimum operating
voltage requirements, and minimum external components.
12
SERVO-DEMAND
The spindle drive function incorporates a three-phase MOS power
TSER DATA IN
SERVO CONTROL
ADJUST
VOLTAGE REF.
VREF(X2)
DUC YDwg.PP-048
Dwg. PP-048
TINUEEDRPERNOCE ONLABSOLUTE MAXIMUM RATINGS
N Fat TA = +25°C
O ELoad Supply Voltage, VCC(PWR) .......... 7.0 V
Spindle Output Current, IOUT(S) ......... ±1.6 A
C RVoice-Coil Output Current, IOUT(S) .... ±0.9 A
ISOutput Current, IOUT(S) ...................... ±1.6 A
RLogic Supply Voltage VCC(D) ............... 6.0 V
Operating Temperature Range,
D OTA ..................................... 0°C to +70°C
FOutput 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
driver and a back-EMF sensing motor commutation scheme. Internal
logic and analog circuitry provide complete start-up and µC-assisted
run modes without the need for snubbers or other external compo-
nents. Additional headroom is achieved by a proprietary circuit, which
eliminates the need for an external current-sense resistor. Intrinsic
ground clamp and flyback diodes are also provided.
The voice-coil function contains a 12-bit DAC, tunable low-pass
and notch filters, and a full-bridge power driver. The MOS outputs
provide increased available voltage and lower power dissipation over
bipolar devices. Voice-coil current is sensed by internal circuitry that
eliminates the need for an external current-sense resistor. Additional
internal circuitry can be configured to provide an over-velocity fault
limit by utilizing the internally monitored current of the voice-coil motor.
The spindle and voice-coil control functions are supplemented by
an ENERGY MANAGER™ subsystem, which efficiently channels available
power to protect the heads and the data disk during system failure or
normal system shutdown. Synchronous rectification of spindle
back-EMF voltage provides nearly lossless conversion of spindle
rotational inertia into power to operate the voice coil motor for parking
the heads. A dc-to-dc converter provides continuous operation at
minimum supply voltages. In addition, the ENERGY MANAGER subsystem
provides several sleep modes and latched fault states for undervoltage
or thermal faults.
The A8980CJT is supplied in a 64-lead thin quad flatpack for
surface-mount applications.
FEATURES
Voice Coil Motor Driver:
s Low rDS(on) MOS Outputs
s Lossless Current Sensing
s Zero Deadband
and/or forced cooling.
s User-Adjustable Transconductance Gain
s Retract Circuitry Functional to 0 V




Allegro MicroSystems

A8980CJT Datasheet Preview

A8980CJT Datasheet

SUPERSERVO SPINDLE & VOICE-COIL ACTUATION MANAGER/DRIVER

No Preview Available !

8980
SUPERSERVO
SPINDLE & VOICE-COIL
ACTUATION MANAGER/DRIVER
FUNCTIONAL BLOCK DIAGRAM
Rgm
R gm
ENERGY MANAGER
CONTROLLED RETRACT
DC-DC CONVERSION
SLEEP MODES
UV FAULT
THERMAL SHUTDOWN
OVER-VELOCITY FAULT
gm
SERVO CONTROL
NOTCH
FREQUENCY,
DEPTH, &
DAMPING
TUNABLE
LOW-PASS
FILTER
12-BIT
SERVO-
DEMAND
DAC
8-BIT
gm
SLEW
SPIN-DEMAND
DAC
RATE
CONTROL
IN / OUT MUX
CONFIGURATION
CONTROL
BACK-EMF AND
COMMUTATION LOGIC
POWER-ON
RESET (TO µC)
V REF
2 V REF
UV TRIP ADJUST
SERIAL DATA IN
CLOCK
DATA ENABLE
2 MHz CLOCK
RETRACT
ANALOG MUX 1
ANALOG MUX 2
DIGITAL MUX OUT
EXTERNAL
COMMUTATION
TACH
Dwg. FP-028B
Spindle Motor Controller/Driver:
s Low rDS(on) MOS Outputs
s Back-EMF Circuitry Eliminates Hall-Effect Sensors
s Programmable Slew Rate Eliminates Snubbers
s Lossless Current Sensing
s Improved Speed Disturbance Performance
s Dynamic Braking with Delay
s Active Braking
Servo Compensator/Notch:
s Over-Velocity Fault Circuitry
s 12-Bit Servo-Demand DAC
s Programmable Complex Pole Low-pass-Filter
s Programmable Notch Frequency, Depth, and Damping
Energy Manager:
s 3.0 V to 5.5 V Operation
s Independent Power-Down (Sleep) Modes for all
Functional Blocks
s Efficient Synchronous Rectification Supplies Power
During Blackout
s Thermal Fault Shutdown Circuitry
s Trimmed Bandgap Voltage Reference
s Smart DAC Reference Generator
s Programmable Voltage Reference for Relative Ground
s Over-Velocity Fault Circuitry
s Supply Under-Voltage Monitor with Adjustable
Trip Point
s System Diagnostics Data Out
s Power-On Reset Generator
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1992, 1994, Allegro MicroSystems, Inc.



Part Number A8980CJT
Description SUPERSERVO SPINDLE & VOICE-COIL ACTUATION MANAGER/DRIVER
Maker Allegro MicroSystems
Total Page 8 Pages
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