CXA2581 Sony Corporation, CXA2581 Datasheet - Page 10

• Manufacturer Part Number: CXA2581
• Description: RF Signal Processor for CD Players
• Manufacturer: Sony Corporation

• EQ
The boost gain can be adjusted by the BST pin control
voltage.
The control characteristics are shown in the graph below.
• 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 photo diode
output at a constant level. This control is performed by the APC function.
In
Boost Gain [dB]
8dB
0dB
HPF
RFC
LPF
VC – 1.0
V
26
CC
VFC
Pin 24 (BST) voltage
fc
EQ CNT
Amp
VC
25
VC
PD
Boost
BST
2
VC
24
VC + 1.0
10k
LPF
55k
Vcnt
[V]
Out
– 10 –
1.25V
10k
10k
56k
The diagram to the left shows the EQ internal block
diagram.
The EQ consists of a combination of HPF and LPF.
The HPF and LPF transmittance is the Bessel function.
The boost gain can be adjusted by adjusting the HPF
gain.
The boost frequency is adjusted by the RFC external
resistance value and the VFC control voltage value.
RFC resistance value: The cut-off frequency fo of each
VFC voltage: fo can be changed by the voltage applied
V
CC
The cut-off frequency control characteristics are
shown in the graph below.
1.5fo
0.5fo
56k
fo
fc [Hz]
to Pin 25.
VC – 1.0
1k
1
filter is adjusted by the Pin 26
external resistance value.
The VFC voltage can be varied
using this fo as the reference.
Pin 25 (VFC) voltage
LD
VC
VC + 1.0
CXA2581N
Vcnt
[V]