AN8807SB
ICs for CD-ROM Player
Pin31, and 32 are used to make the resistance converting the current to voltage variable. When these pins are directly connected
to V
REF
and 20kΩ of resistance is connected between TE and TE–, and between TE and TEOUT respectively, equivalent
resistance to TEOUT is 629kΩ.
Table 2
V
C
1.5V
2.5V
3.5V
E/F
0.14
1.0
7.0
F/E
7.0
1.0
0.14
The VCBA is for tracking balance adjustment in the same way of for focus. Table 2 shows the tracking balance ratio under the
same conditions as shown in Table 1.
• AGC
In order to absorb the attenuation of RF signal by disk, pick-up dispersion, finger print and other factors, AGC circuit for RF is
incorporated.
The input impedance of Pin8 is approx. 27.9kΩ. By Pin10 (ARF), the gain-controlled RF-signal is outputted. Input allowable
level is approx. 1V
P–P
~ 500mV
P–P
~ 250mV
P–P
, and output is 1V
P–P
. Pin9 is a connecting pin with capacity for constructing the
AGC loop filter. It is recommended that the external capacitor of 1µF around should be connected to it for V
CC
.
RF
V
CC
1µF
ARF
8
9
10
AGC
Figure 4 : AGC
• RFDET
The RFDET detects amplitude of RF signal inputted to Pin8. Threshold value is approx. 100mV (f=500kHz), and RF
Present=L, RF Absent=H are outputted.
PANASONIC [ PANASONIC SEMICONDUCTOR ]
