KA3016D 데이터 시트보기 (PDF) - Fairchild Semiconductor

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KA3016D

SPINDLE MOTOR DRIVER

Fairchild Semiconductor 

KA3016D

CD-ROM PRODUCTS

5. ROTATIONAL DIRETION DETECTION

VCC

H2+

+

H2−

−

H3+

+

H3−

−

DIR

20

D

Q

CK

D-F/F

Rotation

Forward

Reverse

20 DIR

Low

High

• The forward and the reverse rotations of the CD are simply detected by using the D-F/F and the truth table is

shown in the above table.

• The rotational direction of the CD can be explained by the output waveforms of the hall sensors. Let the three

outputs of hall sensors be H1, H2 and H3 respectively.

When the spindle rotates in reverse direction, the hall sensor output waveforms are shown in Fig.(a). Thus the

phases orderd in H1→H2→H3 with a 120°C phase difference.

H1

H2

H3

( a) Reverse rotation

On the other hand, if the spindle rotates in forwand rotation, the phase relationship is H3→H2→H1 as shown in

fig.(b).

H1

H2

H3

( b) Forward rotaion

Therefore, the output of the rotational direction detector is low, when the spindle rotates forward, while high as in

the case of the reverse rotation.

10

MIC-99D001

January 1999

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