SAMSUNG max632 Special Circuit Descriptions

5. Special Circuit Descriptions

5-1 CD

5-1-1 RF Amp (KA9220) : WIC01

5-1-2 Focus Error Amp (KA9220) : WIC01

5-1-3 Focus Servo System (KA9220) : WIC01

Photo Detector

PD1 PD2

58K

RF I-V AMP(1)

58K

10K

RF I-V AMP(2)

10K

RF SUMMING

V1 AMP

RFO

RF I-V Amp(I-1) and RF I-V Amp (I-2) are converted to voltage (via internal resistance of 58k½) from the current of PD1 (A+C) and PD2 (B+D): These voltages are added by the RF summing amplifier. The signal (A+B+C+D) is applied to RFO (No.2 terminal) RF output voltage is calculated as follows :

FOCUS ERROR Amp AMPLIFIES the difference between RF I-V Amp (1) output (A+C) and RF I-V Amp (2) output (B+D) These two signals are supplied to (-) and (+) input terminals of the FOCUS ERROR Amp. The FOCUS ERROR signal resulting from this difference voltage is applied to FE (Terminal No. 57). The FE output voltage of this low frequency component varies according to {(A+C) - (B+D)}. VFE is calculated as follows: VFE=(R2/R1) X (V2-V1) = 5.4(V2-V1) This FOCUS ERROR voltage is sent to FOCUS SERVO.

When FS3 is ON, high-frequency gain decreases (time constant is set by pin17, pin19, and capacitor connected to internal resistance). The capacitor between pin18 and GND sets the time constant to pass low freqencies in PLAY mode.

The maximum frequency of focus phase compensation is inversely proportional to the resistance connected to pin 7. Focus search peak is about 1.1 Vp-p, and is inversely proportional to the resistance connected to pins 22,23 (if this resistance changes, the peak of track jump and sled kick change). The inversion input of FZC comparator is set to 5.7% of the difference between Vcc and VC (pin69) {(5.7% x (Vcc-Vc)}. Note : If the resistance connected to pin 7 changes, the phase compensation peak of focus,tracking,sled servos change. At the same time, Ôop-ampÕ dynamic range and offset voltage also change.

VRF = -R3 x (iPD1 + iPD2)

= -R3 x (V1/R1 + V2/R2) = -R3 x ( + ) = x (V1 + V2)

R3 10K

V1 10K

V2 10K

174K

C1 25P

FOCUS ERROR

AMP

164K

FE Bias

GNDVcc

20K

32K

C2 25P

-(A+C)

-(B+D)

V1 32K

3.6K

60K

FZC

0.0022

20K

0.1UF

FDFCT

HFGD

EFR

FE2

470K

DFCT

FS4

20K 48K

58 60

46K

580K FS3

FSW

470K

130K

0.1UF

40K

PFSET

FS2

PHASE COMPENSATION

92K

40K

10K

4.7UF

FSCH

FS1

50K

5.5U 11U

VREG

180K

ISET

FCE

120K

FOCUS COIL

FSEO

Samsung Electronics 5-1

5-1-4 Tracking Sled Servo System (KA9220) : WIC01

The capacitor between pins 15 and 16 attenuates high frequencies when TG2 is off. The maximum frequency of tracking phase compensation is inversely proportional to the resistance connected to pin 7 (about 1.2kHz at 470k). The tracking jump (FWD and REV) is determined when TM3 and TM4 are ON, and the peak voltage induced from tracking coil is decided by both TM3 and TM4 current values and feedback resistance of pin 47. Tracking jump max voltage = TM3 (TM4) current x feedback reisistance.

FWD or REV sled kick occurs when TM5 or TM6 is ON, and the peak voltage added to sled motor is decided by TM5 or TM6 current and the feedbadk resistance of pin 41. Sled jump max voltage= TM5 (TM6) current x feedback resistance Each SW current is decided by the resistance connected to pin 22 and 23. When the resistance is about 150½,

TM3 or TM4 = 11µA,

TM5 or TM6 = 22µA, This current is inversely proportional to the resistor, variable within a range of 5 to 40µA for TM3. STOP is the ON/OFF detection signal for the limit SW (or the sled motorÕs innermost cirumference).

22 23

40 41 39

47 48

0.022UF

TZC

0.047UF

150K

BPF

1K 1K

TZC

100K

ATC

20K

TE 1

TE2

470K

100K

ATS

TDFC1

0.1UF

680K

66PF

10K

DFCT

0.1UF

RTG

20K

TGSW

470K

TG2

82K

110K

PHASE

COMPENSATION

S STOP

100K

S STOP

SLED

SLEI

SLEN

10K

56K

100K

ISET VREG

180K

SLED DRIVER

120K

100K

TKEO

TKEI

TM2

TM6

TM5

TM4

5.5U

TM3

5.5U

10K

90K

TM7

PFSET

470K

TRACKING COIL

Special Circuit Descriptions

5-2 Samsung Electronics