cxd2548r Sony Electronics, cxd2548r Datasheet - Page 55

• Manufacturer Part Number: cxd2548r
• Description: Cd Digital Signal Processor With Built-in Digital Servo And Dac
• Manufacturer: Sony Electronics

[3] Description of Other CD Signal Processing and DAC System Functions
3-1. Description of DSP Operating Modes
This LSI has three basic operating modes using a combination of spindle control and the PLL. The operations
for each mode are described below.
(a) CLV-N Mode
(b) CLV-W Mode
(c) CAV-W Mode
Note) The capture range for this mode is theoretically up to the signal processing limit.
This mode is compatible with the CXD2507AQ, and operation is the same as for the conventional control.
The PLL capture range is ±150kHz.
This is the wide capture range mode. This mode allows PLL to follow the rotational velocity of the disc. This
rotational following control has two types: using the built-in VCO2 or providing an external VCO. The spindle
is the same CLV servo as for the conventional series. Operation using the built-in VCO2 is described below.
(When using an external VCO, input the signal from the VPCO1 pin to the low-pass filter, use the output from
the low-pass filter as the control voltage for the external VCO, and input the oscillation from the VCO to the
VCKI pin.) While starting to rotate a disc and/or speeding up to the lock range from the condition that a disc
stops, CAV-W mode should be used. Concretely saying, firstly send $E665 to set CAV-W mode and kick a
disc, secondly send $E60C to set CLV-W mode if ALOCK is high, which can be read out serially from the
SQSO pin. CLV-W mode can be used while ALOCK is high. The microcomputer monitors the serial data
output, and must return the operation to the speed adjusting state (CAV-W mode) when ALOCK becomes
low. The control flow according to the microcomputer software in CLV-W mode is shown in Fig. 3-2.
In CLV-W mode (normal), low power consumption is achieved by setting LPWR to high. Control was formerly
performed by applying acceleration and deceleration pulses to the spindle motor. However, when LPWR is
set to high, deceleration pulses are not output, thereby achieving low power consumption mode.
CLV-W mode supports control only by the ternary output of the MDP pin. Therefore, when using CLV-W
mode, set DCLV PWM MD to low.
Note) The capture range for this mode is theoretically up to the signal processing limit.
This is CAV mode. In this mode the external clock is fixed and it is possible to control spindle to variable
rotational velocity. The rotational velocity is determined by the VP0 to 7 setting values or the external PWM.
When controlling the spindle with VP0 to 7, setting CAV-W mode with $E665 command and controlling VP0
to 7 with the $DX commands allows the rotational velocity to be varied from low speed to double speed. (See
"$DX Commands".) Also, when controlling the spindle with the external PWM, the PWMI pin is binary input
which becomes KICK during high intervals and BRAKE during low intervals.
The microcomputer can know the rotational velocity using V16M. And the reference for the velocity
measurement is a signal of 132.3kHz obtained by 1/128 of the crystal (384 Fs). The velocity is obtained by
counting V16M/2 pulses while the reference is high, and the result is output from the new CPU interface as 8
bits (VP0 to 7). These measurement results are 31 when the disc is rotating at normal speed or 63 when it is
rotating at double speed. These values match those of the 256 - n for control with VP0 to 7.
In CAV-W mode, the spindle is set to the desired rotational velocity and the operation speed for the entire
system follows this rotational velocity. Therefore, the cycles for the Fs system clock, PCM data and all other
output signals from this LSI change according to the rotational velocity of the disc (excluding the servo output
block).
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CXD2548R