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CXA1372BQ/BS

Description of Functions

Focus Servo

FZC

1.2k

56k

FE

22k

FZC

Focus Phase

Compensation

48k

510k

0.1µ

FSET

FLB

40k

FGD

10k

DFCT

2200p

FE

470k

0.1µ

FDFCT

FS3

580k

46k

100k

FOCUS COIL

FE–

120k

11µ

22µ

ISET

FS1

50k

40k

4.7µ

SRCH

10k

FS2

0.01µ

FEO

0.1µ

20k

FS4

FS3

120k

46

47

48

2

3

4

16

7

17

6

5

DGND

The above figure shows a block diagram of the focus servo.

Ordinarily the FE signal is input to the focus phase compensation circuit through a 20k

Ω and 48kΩ resistance;

however, when DFCT is detected, the FE signal is switched to pass through a low-pass filter formed by the

internal 470k

Ω resistance and the capacitance connected to Pin 48. When this DFCT countermeasure circuit is

not used, leave Pin 48 open.

When FS3 is ON, the high-frequency gain can be cut by forming a low-frequency time constant through a

capacitor connected between Pins 2 and 3 and the internal resistor.

The capacitor connected between Pin 4 and GND is a time constant to boost the low frequency in the normal

playback state.

The peak frequency of the focus phase compensation is approximately 1.2kHz when a resistance of 510k

Ω is

connected to Pin 16.

The focus search level is approximately ±1.1Vp-p when using the constants indicated in the above figure. This

level is inversely proportional to the resistance connected between Pin 17 and GND. However, changing this

resistance also changes the level of the track jump and sled kick as well.

× 2%.

∗ 510kΩ resistance is recommended for Pin 16.