8980

SPINDLE & VOICE-COIL

ACTUATION MANAGER/DRIVER

frequency and programmable notch depth to provide truly independent

control of notch damping. Enough range and granularity are provided

to allow versatile and accurate out-of-band attenuation of undesirable

energy sources.

conductance function of the voice-coil actuation signal path is

achieved by monitoring the load current and generating an error

not carry load current and is intended only for accurate determination

of the transconductance. The function is:

g

A/V

and I

full-bridge power driver operating in a class-B mode. The power

output devices are enhancement-mode MOS transistors. Special

internal circuitry results in nearly zero cross-over distortion when

switching from one source/sink pair to another.

FUNCTIONAL DESCRIPTION

ACTUATOR

is provided to bridge the DSP “soft” domain

to the analog hardware domain. The term

“demand” refers to the distinction between

the newly requested voice-coil current and

the prior current being supplied. The DAC,

operating in straight binary format, spans the

full dynamic range between a large signal

velocity and a precision position mode. The

DAC output is updated synchronously with

the notch functions to avoid the creation of

aliasing products.

intrinsic complex-pole low-pass filter is

provided to attenuate undesirable, out-of-

band information. The input of this discrete

time filter is sampled synchronously with the

12-bit DAC and notch function in order to

avoid aliasing products.

VM

V

BOOST(H)

VBOOST(L)

V

+ V

UNDER-VOLTAGE

FAULT

V

BOOST(H)

VBOOST(L)

SPINDLE

MOTOR DRIVERS

V

BOOST(H)

V

BOOST(L)

VOICE-COIL

DRIVER

TRIP ADJ

POWER

ON

RESET

POR

OUT

REF(x2)

V

REF

V

REFERENCE

ADJUST

V

BOOST(L)

V

BOOST(L)

ADJUST

(FROM SERIAL INTERFACE)

V

V

BOOST(L)

T

J

SHUTDOWN /

SLEEP

DC

M

CC(A)

V

CC(A)

V

CC(D)

VCC(PWR)

CC(A)

V

L FLYBACK

CC(A)

V

BG

V

BG

V

BG

V

VDC

OVER -

VELOCITY

FAULT

RETRACT

MODE

V

CC(A)

REF

V

+

2

VEL

FILTERED

V

REF

V

-

2

V

CC(D)

VRETRACT

BG

V

ADJUST

(FROM SERIAL

INTERFACE)

x2

÷2

BANDGAP

VOLTAGE

REFERENCE

DC-TO-DC

CONVERTER

THERMAL

FAULT

RETRACT

VOLTAGE

REFERENCE

R

gm(act)

5800