LC78626 Sanyo Semicon Device, LC78626 Datasheet - Page 14

• Manufacturer Part Number: LC78626
• Description: DSP for Compact Disk Players
• Manufacturer: Sanyo Semicon Device

6 The CLV Servo Circuit Pin 20: CLV+, Pin 21: CLV-, Pin 22: V/P
* The CLV servo control command is such that the TOFF pin is low only when the CLV mode is in effect, and it is high
(1) The CLV Mode
(2) Switching the Rough Servo Gain
otherwise. The TOFF pin control by the command is only active when the CLV mode is in effect.
CLV
disk. Depending on the commands from the microcontroller, one of the following four modes is selected: Accelerate,
decelerate, CLV, or stop. The CLV
In the CLV mode the rotation of the disk is detected from the HF signal, and a precise linear speed of rotation is
derived by exerting the respective forms on control when the internal modes of the DSP change. The PWM frequency
is 7.35 kHz. The V/P has a high output when the internal mode is the rough servo, and a low output when the internal
mode is phase control.
When the internal mode is the rough servo, the CLV control gain for the 8 cm disk can be reduced by 8.5 dB from the
level for the 12 cm disk.
Rough servo (when the rotational speed is determined to be low)
Rough servo (when the rotational speed is determined to be high)
Phase control (when the PCK clock is running)
Decelerate
Accelerate
MODE
+
Code
Stop
Code
CLV
$04
$05
$06
$07
$A8
$A9
is the signal for accelerating the disk in the forward direction, while CLV
Pulse output
CLV
Internal mode
high
low
low
DISC MOTOR BRAKE (Decelerate)
DISC MOTOR START (Accelerate)
+
DISC MOTOR STOP (Stop)
DISC MOTOR CLV (CLV)
DISC 12 cm Set
DISC 8 cm Set
Pulse output
COMMAND
COMMAND
CLV
high
low
low
+
and CLV
–
–
outputs for each mode are as shown in the table below.
LC78626E
PWM
CLV
high
low
+
RES = low
RES = low
PWM
CLV
high
low
–
high
high
V/P
low
–
is the signal for decelerating the
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