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1. CIRCUIT DESCRIPTIONS
1. Front end section (MN2DS0018MAUB : IC1501)
MN2DS0018MAUB is a 1 chip LSI for DVD-Player. A DVD-Player system can be\
constructed by connecting this LSI,
driver IC, SDRAM, Flash-ROM, Audio-DAC, etc.
This LSI includes a front end (SODC/FE) which executes RF signal proce\
ssing, servo processing and decode
processing, a AV decoder(back end/BE) which executes video decode proc\
essing such as MPEG1/MPEG2/JPEG
and audio decode processing such as DVD-Audio/Dolby Digital /DTS/MP3, \
and a system controller which controls
the system.
The front end section realizes optical head signal computation processin\
g and RF signal processing, digital signal
processing (16-8 demodulation, error correction) for DVD-ROM playback \
according to the DVD specifications,
digital signal processing of CD-DA/CD-ROM (error correction), AV decod\
er transfer, servo control, spindle motor control
and seek control.
In the case of MN2DS0018MAUB, the front end servo system waveforms, such\
as FE, TE and AS, are not observed
as in the case of DVD mechanism module (MS5) CX-3212. Please pay atten\
tion.
1.1 Analog block (MN2DS0018MAUB : IC1501)
The functions of the analog block are as described below.
1. Reference power circuit
2. SERVO system/DPD system signal processing circuit
Gain switching amplifier and Low Pass Filter (LPF)
3. RF signal processing circuit
RF adding circuit, circuit to make inline, Variable Gain Amplifier (\
VGA) circuit
4. Laser power control (LPC) circuit
5. A/D converter for SERVO (10 bit, DPD system-4ch),DPD converter, PWM\
1.1.1 APC circuit
The optical output of the laser diode (LD) has a large negative temper\
ature characteristic.
Therefore, if the LD is driven by a constant current, a constant optical\
output cannot be obtained.
APC circuit is a circuit to control the current so that the output at th\
e monitor diode (MD) will be constant.
MN2DS0016AAUB includes 2 types of APC circuit, one for DVD and the other\
for CD.
The LD current can be obtained by dividing the measured voltage between \
DVDLD1 (CDLD1) and 5 V by 6 Ω
(1.5 Ω x 4=6 Ω), in the case of DVD (CD). It will be approximately 50 mA (45 mA) \
in the case of DVD (CD).
The potential difference between DVDLD1(CDLD1) and 5 V is set to appro\
x. 300 mV(270 mV).
DV5U Chip
(MN2DS0018MAUB : IC1501)
CDMPD 17
DVDMPD
PU UNIT
2
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105
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103
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1.1.2 FE forming circuit
Focus error (FE) forming circuit The signal from PU, FE1 and FE2, are AD converted inside IC1501 and capt\
ured. After that, a differential is obtained by taking the offset cancellation into consideration,
and FE is obtained.
FE = (FE1) - (FE2)
15
14
FE2
FE1
CN1101
115 116VIN7 VIN8 Input AMP
Gain switching
-6 dB, 0 dB, 9.5 dB LPF
50 k/100 kHz LPF
Buffer
LPF
50 k/100 kHz G=0 dB Buffer AMP
Selector
Selector
Gain switching
3 dB, 9 dB
DV5U Chip
ADC driving AMP
Gain switching
6/7.5/9/10.5/
12/13.5/15/
16.5/17/19.5 dB ADC
ADC
After 10 bit ADC FE signal forming circuit
1+Pfbal0,1/0x0100
1-Pfbal0,1/0x0100
Offset cancel
Fbal coarse adjustment value
FE
AMP
DV5U Chip
FE1
FE2 +
-
