KA3011 データシートの表示（PDF） - Fairchild Semiconductor

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KA3011

3-Phase BLDC Motor Driver

Fairchild Semiconductor 

5. ROTATIONAL DIRECTION DETECTION

KA3011BD

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 detected by the D-F/F and the truth table is shown above.

• The rotational direction of the CD can be explained by the output waveform of the hall sensors. 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). The phases order are

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 forward rotation, the phase relationship is H3→H2→H1 as shown in Fig.(b).

H1

H2

H3

( b) Forward rotation

The output of the rotational direction detector is low, when the spindle rotates forward, and high in the reverse rotation.

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