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CXA1372BQ/BS

1-3. SENS (Pin 27)

The output of the SENS pin differs depending on the input data as shown below.

$0X: FZC

$1X: AS

$2X: TZC

$3X: SSTOP

$4X to 7X: HIGH-Z

2. $1X (“AS” at SENS (Pin 27))

These commands deal with switching TG1 and TG2 ON/OFF.

The bit configuration is as follows

D7

D6

D5

D4

D3

D2

D1

D0

0001

ANTI

Break

TG2

TG1

SHOCK

circuit

ON/OFF ON/OFF

TG1, TG2

The purpose of these switches is to switch the tracking servo gain Up/Normal. The brake circuit (TM7) is to

prevent the frequently occurred phenomena where the merely 10-track jump has been performed actually

though a 100-track jump was intended to be done due to the extremely degraded actuator settling caused by

the servo motor exceeding the linear range after a 100 or 10-track jump.

When the actuator travels radially; that is, when it traverses from the inner track to the outer track of the disc

and vice versa, the brake circuit utilizes the fact that the phase relationship between the RF envelope and the

tracking error is 180˚out-of-phase to cut the unneeded portion of the tracking error and apply braking.

Note that the time from the High to Low transition of FZC to the time command $08 is asserted must be

minimized. To do this, the software sequence shown in B is better than the sequence shown in A.

FZC

↓ ?

NO

YES

F. OK ?

NO

Transfer $08

Latch

FZC

↓ ?

NO

F. OK ?

NO

Transfer $08

Latch

(A)

(B)

YES

YES

YES

Fig. 5. Poor and good software command sequences