LB11975 Datasheet, PDF (9/12 Pages) Sanyo Semicon Device – High-Speed CD-ROM Spindle Motor Driver IC

LB11975
Torque Command
Figure 1 shows the relationship between the control voltage (V_CTL) and the RF voltage.
Forward rotation
VRF
Dead zone
Offset voltage
3mV
VCREF=1.65V
1.65V
Figure 1
VCTL
Truth Table
V_CTL > V_CREF
V_CREF > V_CTL
Operation
Forward rotation
Reverse torque braking *
Note: * Since this IC includes a reverse rotation prevention circuit, although the IC will brake the motor if the motor is rotating and V_CTL < V_CREF, when
reverse rotation is detected, the IC will turn the output off, thus stopping motor rotation.
Reverse Rotation Detection Circuit Truth Table
Forward rotation
Reverse rotation
RS pin
HIGH
LOW
IN1+
IN1–
IN2+
IN2–
D
CK Q
R
D
CK Q
R
OUT
During forward rotation:
The OUT signal is set high to reset DFF.
During reverse rotation:
Reverse rotation is detected when the Hall comparator output falls.
At that point the OUT signal is set to the low level.
IN3+
IN3–
VCTL
VCREF
D
CK Q
R
Figure 2 Reverse Rotation Detection Circuit Block Diagram
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