No. 7809-8/24

LV1605M

Test Circuit

Operational Description

• APC (Automatic laser power control)

This circuit is provided to control the pickup laser power. The laser on/off state is set by the microcontroller.

• RF amplifier (eye pattern output)

The (A + C) component of the pickup photodiode output current is input to FIN2 (pin 1), and the (B + D) component

is input to FIN1 (pin 2). The input current is converted to a voltage. That signal is passed through the AGC circuit and

output from the RFSM amplifier output RFSM pin (pin 48). The internal AGC circuit has a variable gain range of ±3

dB, and its time constant can be changed by adjusting the value of the external capacitor connected to PH1 (pin 50).

The bottom level of the EFM signal (the RFSM output) is controlled, and the response of this function can be

changed by adjusting the value of the external capacitor connected to BH1 (pin 59). The center value of the range of

the AGC circuit is set by the value of the resistor inserted between RFSM (pin 48) and RFS- (pin 49). If required,

these pins can also be used for EFM signal 3T compensation. When playing CD-RW discs, the input gain is increased

when the IC receives a signal from the DSP that sets RW (pin 44) low.

F2I

FIN2

AGND

DGND

AGND

AVCC

DVDD

AVCC

FIN1

E

F

TB

TE

–

TE

TESI

SCI

TH

TA

TD

–

TD

JP

TO

FD

RFSM

DRF

DEF

CLK

CLOCK

RW

CE

DAT

CL

INTI

CLV

HFL

TJP

TES

TOFF

TGL

DGND

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

48

47

46

45

44

43

42

41

40

39

38

37

36

35

34

33

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

64

63

62

61

60

59

58

57

56

55

54

53

52

51

50

49

100k

Ω

22k

Ω

15k

Ω

33k

Ω

33k

Ω

F1I

100k

Ω

EI

180k

Ω

56k

Ω

2.2k

Ω

FI

180k

Ω

10k

Ω

10k

Ω

0.01

µF

REF

15k

Ω

REF

62k

Ω

62k

Ω

3300pF

100pF

3300pF

+

0.01

µF

0.01

µF

10

µF

+

+

10

µF

0.01

µF

0.01

µF

+

10

µF

+

47

µF

+

A13933

LV1605M