KA3016D データシートの表示（PDF） - Fairchild Semiconductor

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KA3016D

SPINDLE MOTOR DRIVER

Fairchild Semiconductor 

CD-ROM PRODUCTS

6. REVERSE ROTATION PREVENTION

KA3016D

EC

+

ECR

−

H2+

+

H2−

−

H3+

+

H3−

−

D

Q

CK

D-F/F

Low Active

A

Current

Sense

Amp

Gain

Controller

Driver

M

• When the output of the OR Gate, A is low, it steers all the output current of the current sense amp makes the

current delivered to the gain controller zero. Thus the output current of the driver becomes zero and the motor

is stopped.

• As in the state of the forward rotation, the D-F/F output, Q is high and the motor rotates normally. At this state if

the control input is changed such that EC>ECR, then the motor rotates slowly more and more by the reverse

commutation in the driver. At the moment that the motor rotates in reverse direction, the D-F/F output becomes

low and the OR gate output, thus, becomes low. This prevents the motor from rotating in reverse direction.

The operation principle is shown in the table and the flow chart..

Rotation

Forward

H2

H3

D-F/F

Reverse rotation preventer

(Q)

EC>ECR

EC>ECR

H

H→L

H

Forward

−

Reverse

L

H→L

L

−

Brake and stop

Forward rotation at EC < ECR

Rotating speed is decreased due to reverse torque at EC >ECR. (Motor still rotates forward)

At the moment that the motor rotates in reverse, the reverse rotation preventer makes the output power transistor open.

Rotating reverse at short time due to motor inertia

Stop within 1/6 turn reverse rotating

MIC-99D001

11

January 1999

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