FAN8741G Fairchild Semiconductor, FAN8741G Datasheet - Page 15

• Manufacturer Part Number: FAN8741G
• Description: Analog & Mixed-Signal, Spindle Motor and 6-CH Actuator Driver [Spindle(PWM), Sled 2-CH(PWM) 4-CH(Linear)]
• Manufacturer: Fairchild Semiconductor

5. REVERSE ROTATION PREVENTION(SPINDLE)
1) 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 VREF>SPIN, 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.
VREF
SPIN
HW+
HV+
HW-
HV-
Rotation
Forward
Reverse
+
+
+
-
-
-
the output power stage same as short brake that is lower 3 power transistors are full turn on.
At the moment that the motor rotates in reverse, the reverse rotation preventer makes
Power stage remains short brake scheme until forward rotation command come in
Rotating speed is decreased due to reverse torque at VREF>SPIN
HV
and appropriate mute combination. (Motor still rotates forward)
H
L
CK
D
D-F/F
Rotating reverse at short time due to motor inertia
Q
Forward rotation at VREF< SPIN
H→L
H→L
HW
A
Low Active
D-F/F
(Q)
H
L
Controller
Current
Sense
Amp
Gain
V
REF
Forward
Reverse Rotation Preventer
-
<SPIN
Driver
Brake and Stop
V
FAN8741/FAN8742
REF
-
>SPIN
M
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