FAN8048 データシートの表示（PDF） - Fairchild Semiconductor
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FAN8048 Datasheet PDF : 34 Pages
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FAN8048
2. H-Bridge Driver (CH1, CH2, CH3 and CH4 )
2-1. H-Bridge Driver for Actuators and Sled Motor (CH2, CH3 and CH4)
Channel 2, channel 3, and channel 4 have two inputs FWD and RVE and an H-bridge type of output to the forward or reverse
Sled motor and the Focus and Tracking actuator as shown in Figure 5. The H-bridge driver operation is as in the following log-
ical truth table below. That is, to forward or reverse, the output is the same as the input, and when the two input signals match,
the lower switching devices (switches B and C) are turned-on, Sled motor, Focus and Tracking actuator are in braking state.
FWD 32
REV 31
VG
VSYS
PVCC
A
VA
VB
D
OUT+
44
VC
43
VD
OUT-
B
C
LOGIC AND PREDRIVER
Figure 5. Block Diagram of H-Bridge driver for CH2, CH3 and CH4
2-2. Logical Truth Table
FWD
REV
L
L
L
H
H
L
H
H
OUT+
L
L
H
L
OUT-
L
H
L
L
Function
Brake
Reverse
Forward
Brake
2-3. H-Bridge driver for spindle motor (CH1)
Figure 6 shows spindle motor driver. The circuit consists of 3-states of input (High, Low, and High impedance) to perform for-
warding, reversing, and braking of the motor. The detailed operation is shown in logical truth table.
VSYS1
50K 70K 40K
CH1 30
MO1
VG
VSYS
PVCC
A
VA
VB
D
CH1+
46
50K 60K 80K
MO2
VC
VD
B
45
CH1-
C
LOGIC AND PREDRIVER
OUTPUT STAGE
Figure 6. Block Diagram of H-Bridge driver for Spindle motor
2-4. Logical Truth Table
INPUT
MO1
MO2
CH+
CH-
Function
H
H
H
H
L
Forward
L
L
L
L
H
Reverse
Z
L
H
L
L
Note:
1. Z is high impedance input
Brake
13
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