LC78626E Datasheet, PDF (14/32 Pages) Sanyo Semicon Device – DSP for Compact Disk Players

LC78626E
6 The CLV Servo Circuit Pin 20: CLV+, Pin 21: CLV-, Pin 22: V/P
Code
$04
$05
$06
$07
COMMAND
DISC MOTOR START (Accelerate)
DISC MOTOR CLV (CLV)
DISC MOTOR BRAKE (Decelerate)
DISC MOTOR STOP (Stop)
RES = low
q
CLV⁺ is the signal for accelerating the disk in the forward direction, while CLV^– is the signal for decelerating the
disk. Depending on the commands from the microcontroller, one of the following four modes is selected: Accelerate,
decelerate, CLV, or stop. The CLV⁺ and CLV^– outputs for each mode are as shown in the table below.
MODE
Accelerate
Decelerate
CLV
Stop
CLV⁺
high
low
Pulse output
low
CLV^–
low
high
Pulse output
low
* 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
otherwise. The TOFF pin control by the command is only active when the CLV mode is in effect.
(1) The CLV Mode
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.
Internal mode
CLV⁺
CLV^–
V/P
Rough servo (when the rotational speed is determined to be low)
high
low
high
Rough servo (when the rotational speed is determined to be high)
low
high
high
Phase control (when the PCK clock is running)
PWM PWM
low
(2) Switching the Rough Servo Gain
Code
$A8
$A9
COMMAND
DISC 8 cm Set
DISC 12 cm Set
RES = low
q
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.
No. 5692-14/32