CXA1992 SONY [Sony Corporation], CXA1992 Datasheet - Page 23

• Manufacturer Part Number: CXA1992
• Description: RF Signal Processing Servo Amplifier
• 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 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 510kΩ 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 V
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 Vcc and VC (Pin 51); (Vcc – VC)
10k
10k
510kΩ resistance is recommended for Pin 11.
2200p
0.022µ
0.1µ
680k
0.1µ
52
3
1
4
2
FZC
FEO
FEI
FDFCT
FGD
FE
100k
DFCT
51k
FS3
9k
75k
FS4
FZC
68k
0.1µ
FLB
SENS
SELECTOR
5
– 23 –
40k
Focus
phase
Compensation
FSET
510k
11
0.015µ
FS2
50k
100k
8
50k
4.7µ
SRCH
11µ
22µ
FS1
Charge
up
FE_M
FE_O
15%.
EE
17
25 SENS1
6
7
. However, changing
ISET
100k
60k
FOCUS COIL
CXA1992AR