CXA2647 查看數據表（PDF） - Sony Semiconductor

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CXA2647

RF Signal Processor for CD Players

Sony Semiconductor 

CXA2647N

• EQ

The EQ internal block diagram is shown below. The EQ is configured with the filter of the Bessel function of

order 4.

Boost

Control

24 BST

79.517fc2

LPF1 =

S2 + (17.085fc) S + 79.517fc2

In

HPF1

Amp

Control Bias

S2

VC – 1V to VC + 1V HPF1 = S2 + (17.085fc) S + 79.517fc2

LPF1

LPF2

Out

99.963fc2

LPF2 =

S2 + (12.412fc) S + 99.963fc2

fc Control

RFC 26

33kΩ to 100kΩ

25 VFC

Control Bias

VC – 1V to VC + 1V

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.

Gain

8dB

fc Freq.

5dB

Boost

gain

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

filter is adjusted by the Pin 26

external resistance value.

The VFC voltage can be varied

using this fc as the reference.

VFC voltage: fc can be adjusted by the voltage applied

to Pin 25. The cut-off frequency control

characteristics are shown in the graph

below.

1.5fc

fc

–1dB

0.5fc

VC – 1.0

VC

VC + 1.0

BST voltage [V]

• APC (Automatic Power Control)

VC – 1.0

VC

VC + 1.0

VFC voltage [V]

RFC pin external resistor value 100kΩ: fc = 1.6MHz

33kΩ: fc = 4.8MHz

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.

VCC

PD 2

10k

56k

10k

55k

10k

56k

1.25V

– 10 –

1 LD

1k

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