2CX-3283
12 3 4
A
B
C
D
E
F
12 3 4
1. CIRCUIT DESCRIPTION
1.1 ANALOG BLOCK (MN2DS0018MA : IC1501)
MN2DS0018MA is a one-chip LSI for a DVD Player. By connecting the LSI with a driver IC, SDRAM, Flash-ROM, Audio-DAC
and so on, a DVD Player system can be established.
The LSI incorporates the Front End (SODC / FE) to process RF signals / servo / decode, AV decoder (Back End / BE) to
process video decode such as MPEG1 / MPEG2 / JPEG and audio decode such as Dolby Digital / DTS / MP3, and a system
controller to control the system.
The Front End part processes the optical head signal computing and RF signals, the digital signals to play DVD-ROM compliant
with the DVD format (16 - 8 demodulation, error correction), and the digital signals (error correction) for CD-DA / CD-ROM,
as well as conducts AV decoder forwarding, servo control, spindle motor control and seek control.
Please note that in this MN2DS0016AAUB, the servo-related waveforms in the Front End, such as FE, TE, and AS, cannot be
observed, as in the case of a DVD mechanism module (LS1) CX-3250.
FRONT END SECTION(MN2DS0018MA : IC1501)
The functions of the analog block are:
1. Reference supply circuit
2. Signal processing circuit for the SERVO system / DPD system
Gain switching amplifier and Low Pass Filter (LPF)
3. RF signal processing circuit
RF addition circuit, Inline circuit, Variable Gain Amplifier (VGA) circuit
4. Laser Power Control (LPC) circuit
5. A/D converter for SERVO (10 bit), DPD system comparator, PWM
1.1.1 APC Circuit
The optical output of a Laser Diode (LD) has large negative temperature characteristics.
Therefore, driving LD with constant current will not get you constant optical output.
The APC circuit controls the current so that the output will be constant using a Monitor Diode (MD).
The MN2DS0018MA incorporates two types of APC circuits; one is for DVD and the other is for CD.
The LD current for a CD is calculated by dividing the measured voltage between CDLD1 and 5V by 15 ohm (3.9 ohm × 3 +
3.3 ohm = 15 ohm).
For a DVD, the current is calculated by dividing the measured voltage between DVDLD1 and 5V by 12 ohm (3.3 ohm × 2 +
2.7 ohm × 2 = 12 ohm).
The result will be about 50 mA (45 mA) for DVD (CD).
The potential difference between DVDLD1(CDLD1) and 5 V is set to approx. 600 mV(675 mV).
On this or later version of the DVD mechanism module, the Power adjustment circuit (which is the circuit from IMON to CDMP
and DVDMP) that adjusts the optical output of the LD is mounted on the mechanism module board. Therefore, it is required to
adjust power when the CRG mechanism (equipped with the PU unit) or the mechanism module board is replaced.
For details, refer to the Power Adjustment Specifications.
IC1501
MN2DS0018MA
CDL1
DVDL1
CDL0
DVDL0
CN1101
13:78LD
22:IMON
14:65LD
106:LPC02
105:CDMPD
104:LPC01
103:DVDMPD
PU Unit
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