CXA1782 SONY [Sony Corporation], CXA1782 Datasheet - Page 18

• Manufacturer Part Number: CXA1782
• Description: RF Signal Processing Servo Amplifier for CD players
• Manufacturer: SONY [Sony Corporation]

Focus Servo
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 68kΩ resistance; however,
when DFCT is detected, the FE signal is switched to pass through a low-pass filter formed by the internal
100kΩ resistance and the capacitance connected to Pin 3. When this DFCT prevention circuit is not used,
leave Pin 3 open. The defect switch operation can be enabled and disabled with command.
The capacitor connected between Pin 5 and GND is a time constant to raise the low frequency in the normal
playback state.
The peak frequency of the focus phase compensation is approximately 1.2kHz when a resistance of 510Ω is
connected to Pin 11.
The focus search height is approximately ±1.1Vp-p when using the constants indicated in the above figure.
This height is inversely proportional to the resistance connected between Pin 17 and VEE. However, changing
this resistance also changes the height of the track jump and sled kick as well.
The FZC comparator inverted input is set to 15% of V
510kΩ resistance is recommended for Pin 11.
22k
0.47µ
2200p
0.1µ
680k
10k
3
1
4
2
FEO
FEI
FDFCT
FGD
100k
DFCT
51k
9k
FS4
FE
68k
0.1µ
FLB
FZC
5
– 18 –
CC
40k
Focus
phase
Compensation
FSET
510k
and VC (Pin 48); (V
11
0.01µ
FS2
50k
100k
8
50k
4.7µ
SRCH
CC
11µ
– VC)
22µ
FE_M
FE_O
FS1
15%.
17
6
7
ISET 120k
100k
FOCUS COIL
CXA1782CQ/CR