cxa2647n Sony Electronics, cxa2647n Datasheet - Page 10

• Manufacturer Part Number: cxa2647n
• Description: Rf Signal Processor For Cd Players
• Manufacturer: Sony Electronics

• EQ
The EQ internal block diagram is shown below. The EQ is configured with the filter of the Bessel function of
order 4.
The boost gain can be adjusted by the BST (Pin 24)
control voltage.
The control characteristics are shown in the graph
below.
The boost gain stands for the increased gain from the
low frequency gain in the fc frequency.
• APC (Automatic Power Control)
When the laser diode is driven by a constant current, the optical power output has extremely large negative
temperature characteristics. Therefore, the current must be controlled to maintain the monitor photodiode
output at a constant level. This control is performed by the APC function.
In
–1dB
8dB
5dB
33k to 100k
VC – 1.0
HPF1
LPF1
RFC
BST voltage [V]
fc Control
26
VC
Amp
PD
25
Control Bias
VC – 1V to VC + 1V
VC + 1.0
VFC
2
Gain
10k
Boost
Control
LPF2
Boost
gain
55k
fc
24
Freq.
Out
Control Bias
VC – 1V to VC + 1V
BST
– 10 –
1.25V
10k
10k
56k
The boost gain can be adjusted by adjusting the HPF1
gain.
The cut-off frequency is adjusted by the RFC external
resistance value and the VFC control voltage value.
RFC resistance value: The cut-off frequency fc of each
VFC voltage: fc can be adjusted by the voltage applied
V
CC
1.5fc
0.5fc
56k
fc
RFC pin external resistor value 100k : fc = 1.6MHz
LPF1 =
HPF1 =
LPF2 =
VC – 1.0
to Pin 25. The cut-off frequency control
characteristics are shown in the graph
below.
1k
1 LD
filter is adjusted by the Pin 26
external resistance value.
The VFC voltage can be varied
using this fc as the reference.
S
S
S
VFC voltage [V]
2
2
2
+ (17.085fc) S + 79.517fc
+ (17.085fc) S + 79.517fc
+ (12.412fc) S + 99.963fc
VC
79.517fc
99.963fc
33k : fc = 4.8MHz
S
2
VC + 1.0
2
2
CXA2647N
2
2
2