8980
SUPERSERVO™
SPINDLE & VOICE-COIL
ACTUATION MANAGER/DRIVER
DISCONTINUED PRODUCT
— FOR REFERENCE ONL
Y
Dwg. PP-048
V
REF
V
REF(X2)
SER DATA IN
C TAP
12
ADJUST
8
VOLTAGE REF.
SERIAL INTERFACE
SPIN-DEMAND
SERVO-DEMAND
BACK-EMF and
COMMUTATION LOGIC
SERVO CONTROL
MULTIPLEXER
ENERGY MANAGER
Dwg. PP-048
SUPERSERVO
TM
SPINDLE & VOICE-COIL
ACTUATION MANAGER/DRIVER
FEATURES
Voice Coil Motor Driver:
a73 Low r
DS(on)
MOS Outputs
a73 Lossless Current Sensing
a73 Zero Deadband
a73 User-Adjustable Transconductance Gain
a73 Retract Circuitry Functional to 0 V
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.
The spindle drive function incorporates a three-phase MOS power
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.
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.
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(S)
.... ±0.9 A
Output Current, I
OUT(S)
...................... ±1.6 A
Logic Supply Voltage V
CC(D)
............... 6.0 V
Operating Temperature Range,
T
A
..................................... 0°C to +70°C
Data Sheet
26310
8980