8980

SPINDLE & VOICE-COIL

ACTUATION MANAGER/DRIVER

DISCONTINUED

PRODUCT

—

FOR

REFERENCE

ONL

Y

Dwg. PP-048

SER DATA IN

12

ADJUST

8

VOLTAGE REF.

SPIN-DEMAND

SERVO-DEMAND

BACK-EMF and

COMMUTATION LOGIC

SERVO CONTROL

Dwg. PP-048

TM

SPINDLE & VOICE-COIL

ACTUATION MANAGER/DRIVER

FEATURES

Voice Coil Motor Driver:

s Low r

s Lossless Current Sensing

s Zero Deadband

s User-Adjustable Transconductance Gain

s 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

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

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

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)

.........

Voice-Coil Output Current, I

OUT(S)

....

Output Current, I

OUT(S)

......................

Logic Supply Voltage V

CC(D)

............... 6.0 V

Operating Temperature Range,

T

A

..................................... 0

8980