Samsung DVD-808 Circuit Descriptions

Samsung Electronics 7-1

7-1-1 Comparison between linear power supply and SMPS

7-1-1(a) LINEAR

Fig. 7-1 Linear Power Supply

Input : Common power to transformer(Vp)

Fig. 7-2

The output Vs of transformer is determined by the ratio of 1st Np and 2st Ns. Vs = (Ns/Np) x Vp

Fig. 7-3

Vout is output (DC) by diode and condensor.

Fig. 7-4

7. Circuit Descriptions

7-1 SMPS

Vreg

Vout

+ –

(Ns)

(Np)

Regulator

Common power (Ex.220V60Hz)

Vout

3 Waveform/Description

20µs

220 2V

Circuit Descriptions

7-2

Samsung Electronics

3 Advantages and disadvantages of linear power supply a. Advantages :

Little noise because the output waveform of transformer is sine wave.

b. Disadvantages :

» Additional margin is required because Vs is changed

(depending on power source). (The regulator loss is caused by margin design).

» Greater core size and condensor capacity are needed,

because the transformer works on a single power frequency.

Fig. 7-5

7-1-1(B) SMPS(PULSE WIDTH MODULATION METHOD)

Fig. 7-6 SMPS

3 Terms

- 1st : Common power input to 1st winding.

- 2nd : Circuit followings output winding of transformer.

- f(Frequency) : Switching frequency(T : Switching cycle)

- Duty : (Ton/T) x 100

Vreg

Vout

0 t

Change by common power

Regulator loss

Transformer Vout

(Np)

(Vp)

Switch

Vs switch

I switch

Vin

ON/OFF Control

–

(Vs)

(Ns)

Regulator

Circuit Descriptions

Samsung Electronics 7-3

7-1-2 Circuit description(FLY-BACK PWM(Pulse Width Modulation) control)

7-1-2(a) AC power rectification/smoothing terminal

- PD01,PD02,PD03,PD04 : Convert AC power to DC(Wave rectification)

- PO03 : Smooth the voltage converted to DC(Refer to VIN of Fig. 7-7)

- PC01, PC02, PC10, PC11, PC12, PC13, PL01, PL02, PL03 : Noise removal at power input/output

- PVA1 : SMPS protection at power surge input (PVA1 pattern open is to remove noise)

- PR10 : Rush current limit resistance at the moment of power cord insertion. » Rush current = (AC input voltage x 1.414 - Diode drop voltage) / Pattern resistance + PL02,01

resistance + PC10 resistance + PR10) (AC230V based : approx. 26A)

» Without PR10, the bridge diode might be damaged as the rush current increases.

7-1-2(b) SNUBBER circuit : PR15, PR16, PC04, PD05, PD11, PR17

- Prevent residual high voltage at the terminals of switch during switch off/Suppress noise.

High inverted power occurs at switch (PIC1) off, because of the 1st winding of transformer: (V=L1xdi/dt. LI : Leakage Induction) A very high residual voltage exists on both terminals of PIC1 because dt is a very short.

- SNUBBER circuit protects PIC1 from damage through leakage voltage suppression by RC, (Charges the leakage voltage to PD11 and PC04, and discharges to PR15 and PR16).

- PC05, PL17 : For noise removal

Fig. 7-7

7-1-2(c) PIC1 Vcc circuit

- PR11, PR12, PR13, PR14 : PIC1 driving resistance (PIC1 works through driving resistance at power cord in)

- PIC1 Vcc : PR18, PD12, PC06

1) Use the output of transformer as Vcc, because the current starts to flow into transformer while PIC1 is active.

2) Rectify to PD12 and smooth to PC06.

3) Use the output of transformer as PIC1 Vcc : The loads are different before and after PIC1 driving. (Vcc of PIC1 decreases below OFF voltage, using only the resistance due to load increase after PIC1 driving.)

Vswitch

Toff

Inverted power by leakage inductance

Circuit Descriptions

7-4

Samsung Electronics

7-1-2(d) Feedback control circuit

Fig. 7-8

- F/B terminal of PIC1 determines output duty cycle.

- C-E(Collector-Emitter) of PIC2 and F/B potential of PIC1 are same.

3 Operation descriptions a. Internal OP-Amp ‘+’ base potential of PIC3 is 2.5V and external “-” input potential is connected with PR38

and PR39 to maintain Vout of 5.8V. (Vout = ((PR36 x PR39) / PR39) x 2.5V)

b. If load of 5.8 V terminal increases(or AC input voltage decreases) and Vout decreases below 5.8V, then :

PIC3 ‘P’ potential down below 2.5V --> PIC3 A-K of base current down --> PIC3 of A-K current down --> PIC2 Diode current down --> PIC2 C-E current down --> PIC2 C-E voltage up --> PIC1 F/B voltage up --> Out Duty up --> Transformer 1st current up --> Transformer 1st power up --> Vout up --> Maintain Vout 5.8V

c. If load of 5.8 V terminal decreases(or AC input voltage rises) and Vout rises above 5.8V, then :

Reverse sequence of the above description Æ Duty down Æ Vout down Æ Maintain 5.8V (i.e., the feedback to maintains 5.8V).

- PR35, PR36 : Reduce 5.8V overshoot

- PR37, PC44 : Prevent PIC3 oscillation(for phase correction)

- PC09 : Adjust feedback response rate

1st

2nd

Circuit Descriptions

Samsung Electronics 7-5

7-1-3 Internal block diagram

7-1-3(a). Internal block diagram of SMPS circuit

Fig. 7-9

7-1-3(b). PIC1(1L0380) internal block diagram

Fig. 7-10

Voltage

Ref.

UVLO

#3 Vcc

#2 Drain

#1 Source GND

Sense

CCoonnttrrooll IICC

SS ee nnss ee

FF EE TT

osc.

Vck

32V

Feedback

LEB

Reset

7.5V

Reset

Thermal Proction

OVP

2uA

6.3V

Sync.

2.5R

Voffset

Rsense

1mA

Noise

removal

(SNUBBER)

Smoothing

circuit

Rectified circuit

Line filter

Power IN

(85~265V)

FLT driving

circuit

5V rectified

smoothing circuit

3.3V rectified

smoothing circuit

Converter

PWM control cir-

cuit (1L0380)

Voltage

detection

circuit

8V rectified

smoothing circuit

-8V rectified

smoothing circuit

5V rectified

voltage

circuit(x2)

3.3V rectified voltage

circuit

Moter 8V 1

port

8V rectified

voltage

circuit

-8V rectified voltage

circuit

O U

T P U

7-6

Samsung Electronics

7-2-1 RIC1(TA1236F)

TA1236F is combined with TA1253FN, TC9240F and TC90A19F as bipolar IC developed for DVD SERVO system. Main features include DVD waveform equalizing, CD waveform equalizing, focus error signal generation, 3-beam tracking error signal generation, laser power control, etc. after receiving the pick-up output converted into I/V.

7-2-1(a) Basic potentiometer

TA1236F uses a single power method and each circuit is based on VREF of 2.1V. Note : symmetrical about GND for VREF because VREF(pin20) terminal is needed for IC, which uses the peripheral VREF and 2VREF output(pin18).

7-2-1(b) RF signal

Fig. 7-11 shows the flow of signal generated by the pick-up.

A, B, C, D signals detected from pick-up are converted in to RF signal(A+B+C+D) via RF summing AMP.

RF signal is inputted to RFN(pin55) among input terminals and RFP(pin54) is used for AC ground.

Fig. 7-11

Fig. 7-12 shows the waveform-equalizing block diagram for the RF signal. It outputs to EQout(pin 46) terminal by initially changing switching AMP gain of DVD and CD, and then adjusting the level in VCA. It controls VCA gain by means of RF gain(pin 48) and interfaces with PWM signal, (output from RFGC terminal of TC9420F, via low-pass filter to constitute a loop for adjustment of constant amplitude). The gain in EQout is 1.0 for DVD and 1.67 for CD.

EQout terminal is connected with EQin(pin 45) externally, and inputs into DVD EQ and CD EQ(Waveform equalizing circuit).

PICK-UP

D A C B

I-V AMP

RC12

104

RR20

RC10

104

RR19

–

RC15

104

RR24

RC14

104

RR22

RR18

1.2K

RIC3 OPA650

SUMMING AMP

2 3

RC11

104

RR23

10K

RR50

5.6K

RR51

5.6K

RC22

104

RR33

10K

Vref

RIC1

TA1236

RFN

Vref

RFP

+5A

7-2 RF circuit description

Circuit Descriptions

Samsung Electronics 7-7

Fig. 7-12

The control parameters of DVD EQ and CD EQ are as follows.

1) DVD EQ control parameter

- DVDEQ(pin 43) : Changes the gain of peak frequency with EQ frequency characteristic. Convert PWM signal, output from TC90A19F, into DC via low-pass filter.

- DVDTIME(pin 41) : Changes the peak frequency with EQ frequency characteristic. Convert PWM signal, output from TC90A19F, into DC via low-pass filter.

- S/Dse1(pin 64) : Changes the peak frequency (like DVD TIME) as 2d control. ( Switched according to regeneration speed ratio of single/double layer).

- MCK(pin 15) : Input the base clock and link the peak frequency with it. The amplitude of MCK might be

small (500mVp-p).

- DVDGD(pin 25) : Changes the group delay characteristics with EQ frequency characteristic.

2) CD EQ control parameter

- CD EQ(pin 40) : Changes the gain of peak frequency with EQ frequency characteristic. The constant DC is supplied to a resistive voltage divider.

- CD TIME(pin 42) : Changes the peak frequency with EQ frequency characteristic. The constant DC is

supplied to a resistive voltage divider.

- S/Qse1(pin 44) : Changes the peak frequency (such as CD TIME) as 2d control. (Switched according to

play linear velocity ratio of quadruple/single rate. Set to ‘0’ because only one rate is vaild in this system).

DVDsel RFgain EQout EQin

CDEQCD

TIME SQsel

RFN

RFP

47 48 46 45 40 42 44

64 41 43 15

VCA

ATT

CD EQ

DVD EQ

RIC1

TA1236F

GEN.

T/CON

SDsel DVD

TIME

DVDEQMCK

DVD G/D

DVD EQ OUT

CD EQ OUT

CD and DVD signals are equalized according to the above control parameters ,and then output to CD EQ OUT (pin39) and DVD EQ OUT (pin34). Then, CD signal is transferred to TC9420F (pin 38), DVD signal is sent to TC90A19F(pin 50) and detected.

7-8

Samsung Electronics

7-3 System control

7-3-1 Outline

The main micom peripheral circuit is composed of 16bit Micom(MIC1,TMP93CS41), 2M PROM (MIC2,AM27C020 for Microcode and data save, 1M SRAM(MIC3, KM681000) for data read/write on running, 512 byte EEPROM (MIC5, IS24C02)for permanent storage of data needed at power off, MIC4(74AC573) to latch only address in the bus where address and data are mixed, address decoder (MIC6, 74HC00) for selection of external device chip and 20MHz clock oscillator for micom operation. The micom(MIC1, TMP93CS41) mounted in main board analizes the key commands of front panel or instructions of remote control through communication with micom(FIC1, LC86P6232) of front and controls the devices on board to execute the corresponding commands after initializing the devices connected with micom on board at power on.

Circuit Descriptions

Samsung Electronics 7-9

7-3-2 Block diagram

Fig.7-13

AIC1,2,3

D/A CONVERTER

PCM1720,1723

AIC1

VIDEO ENCODER

SAA7128

MIC4

74AC573

LOW ADDRESS

HIGH ADDRESS

DATA BUS

MIC1

MAIN MICOM

TMP93CS41F

FIC1

FRONT

MICOM

LC86P6232

MIC6

ADDRESS

DECODER

MICOM

BLOCK

MIC5

EPROM

IS24C02

MIC2

EPROM

AM27C020

MIC3

SRAM

KM681000

BIC1

A/V DECORDER

ZiVAD6-L

DIC1

DVD PROCESSOR

TC90A19F

SIC7

CD PROCESSOR

TC9420F

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