DVD-S530/DV-S5550
DVD-S530/DV-S5550
25
• KILL_LR: This is a signal from the audio DAC, when it
receives no input for a certain time (8192 LRCK cycles).
It can be tested in STOP, PAUSE and during track
changes.
The logic level for the MUTE signal is -3V < LOW < 0V and
0V < HIGH < +3V.
Mute Truth Table
KILL
KILL_LR
MUTE
Function
0
0
0
Output is not muted.
0
1
1
Output is muted.
1
0
1
Output is muted.
1
1
1
Output is muted.
Fig. 8
5. Mono Board
SD4.0 Block Diagram
Loader
Front-end
Loader interface
D
Program
memory
Iguana
(front-end
processor)
Back-end
SMI
STi55xx
EMI
(SDRAM)
(back-end
processor)
(Flash memory /
SDRAM)
Audio
Video
Others
Module
interface
Fig. 9
5.1 Front-end: the Servo Part
The front-end consists of:
• The loader interface.
• The analog DVD signal processor and laser supply.
• DVD front-end processor.
• Program memory.
The Signal Processor TZA1033
The TZA1033 (or DVDALAS2plus) is an analog pre-
processor and laser supply circuit. It contains data
amplifiers and several options for radial tracking and focus
control.
It is possible to optimise the dynamic range of this pre-
amp/ processor combination for the LF servo and RF data
p a t h s . T h e g a i n i n b o t h c h a n n e l s i s s e p a r a t e l y
programmable. This will guarantee an optimal playability
for all kind of discs.
Also, a dual laser supply is implemented, with fully
automatic laser control including stabilization and an ON/
OFF switch, plus a separate supply pin for power
efficiency.
In the SD3.0 module, the servo signals were fed to the
MACE2 servo processor, while the HF output signal was
fed to the SAA7335 decoder. In the new SD4.0 module,
these ICs are combined into one chip: the SAA7812
Iguana.
This chip contains the following blocks: channel decoder,
block decoder, servo processor, and microcontroller.
The Servo Processor/Decoder SAA7812
The servo circuit in the SAA7812 (item 7200) takes care of
the servo controls.
In a CD system, there are some 12 control loops active.
About six of them are needed to adjust the servo error
signals, that is once per disc rotation. It also adjusts
offsets, signal amplitudes, and loop gains (AGCs), to
enlarge system robustness and to avoid expensive
potentiometer adjustments in production.
The other six loops determine the laser spot position on
the disc in the radial, axial (focus), and tangential
directions.
It also has to take care that the spot accesses a required
position as fast as possible. This access system consists
of two parts, namely the actuator and the sled, which are
(within a certain range) mechanically and electrically
independent.
Therefore, during an access, the servo has to control as
well the actuator as the sled.
The analog signals, from the diode pre-processor, are
converted into a digital representation using A/D
converters.
For the communication between the host processor
(STi5580) and the servo processor, the S2B bus is used.
T h i s b u s s u p p o r t s f u l l - d u p l e x a s y n c h r o n o u s
communication.
The SAA7812 is also a combined CD/DVD compatible
decoding device. The device operates with built in
hardware for CD/DVD error correction and de-interleaving
operations. It decodes EFM or EFM+HF signals directly
from the laser pre-amplifier, including analog front-end,
PLL data recovery, demodulation, and error correction.
Its analog front-end input (the channel decoder), converts
the HF input signal to the digital domain via an 8-bit ADC,
preceded by an AGC circuit to obtain the optimum
performance from the converter. An external resonator
clocks this block.
This subsystem recovers the data from the channel
stream. It corrects asymmetry, performs noise filtering and
equalization, and finally recovers the bit clock and data
from the channel using a digital PLL.
The demodulator part detects the frame synchronization
signals and decodes the EFM (14 bit) and EFM+ (16 bit)
data and sub-code words into 8-bit symbols. Via the serial
output interface, the I 2 S data (audio and video) go to the
DVD decoder STi5580.
