AN8807SB Datasheet, PDF (6/10 Pages) Panasonic Semiconductor – Three-Beam Method Head Amplifier IC for CD-ROM

AN8807SB
ICs for CD-ROM Player
s Operational Description (The values shown below are design values when supply voltageVCC=5V.)
• RF Amplifier
As shown in Figure 1, RF signals are generated by three-beam method pick-up. Equivalent resistance to RFOUT (Pin7) is
57.6kΩ, when resistance between RF– and RFOUT is 12kΩ.
48kΩ
12kΩ
Light level
AB
DC
36
–
+
48kΩ
35
–
RRF
6
7
10kΩ
–
10kΩ
+
Dark level
+
RRF (T)= 48kΩ ×
RRF
10kΩ
Figure 1 : RF Amplifier
• Focus Error Amplifier
As shown in Figure 2, the operation result of (A+C) – (B+D) is outputted to FEOUT (Pin27). Equivalent resistance to FEOUT
is 96kΩ, when resistance between FE and FEOUT is 20kΩ.
48kΩ
VCBA
36
–
A+ C
20kΩ
RFE
28
27
AB
+
–
–
DC
48kΩ
20kΩ
+
+
B+D
35
–
+
29
–
VC
+
×2
fC =30kHz
Figure 2 : Focus Error Amplifier