FAN8420D3 Просмотр технического описания (PDF) - Fairchild Semiconductor

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FAN8420D3

3-Phase BLDC Motor Driver

Fairchild Semiconductor 

FAN8420D3

H1

H2

H3

(b) Forward rotation

Therefore, the output of the rotational direction detector is low, when the spindle rotates forward, and high in the reverse rota-

tion.

6. Reverse Rotation Prevention

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 to the Gain Controller

zero. The output current of the Driver becomes zero and the motor stops.

• 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 by the reverse commutation in the Driver. When

the motor rotates in reverse direction, the D-F/F output becomes Low and the OR Gate output, 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

Reverse

Reverse rotation preventer

H2

H3

D-F/F(Q)

EC<ECR

EC>ECR

H

H→L

H

Forward

-

L

H→L

L

-

Brake and stop

Rev. 1.0.1

11

Oct. 2000.

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