CXA2542Q 데이터 시트보기 (PDF) - Sony Semiconductor

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CXA2542Q

RF Signal Processing Servo Amplifier for CD Player

Sony Semiconductor 

CXA2542Q

APC & Laser Power Control

VCC

R1

C2

22

100µ

LD

34

R6

1k

VCC

L1

10µH

130mV

PD

35

C1

R3

1µ

100

R2

500

LD PD

GND

VEE

RF_I

30

R10

R8

56k

10k

LDON

R5

R4 55k

10k

VEE

1.1Vpp

R12

R11

56k

10k

VREF

VEE

VL

LPC ON/OFF

R14

12.5k 50%/17%

C3

0.01µ

31

RF_O

R7

1.47V 39.5k

R9

RF

23.5k

VC

670mV

VC

33

R13

1M

C4

1µ

VEE VEE

• APC

When the laser diode is driven by a constant current, the optical power output has extremely large negative

temperature characteristics.

The APC circuit is used to maintain the optical power output at a constant level.

The laser diode current is controlled according to the monitor photodiode output.

• Laser power control

The RF level is stabilized by attaching an offset to the APC VL and controlling the laser power in sync with the

RF level fluctuations.

The RF_O and RF_I levels are compared and the larger of the two is smoothed by the RFTC's external CR.

This signal is then compared with the reference level.

The laser power is controlled by attaching an offset to VL according to the results of comparison with the

reference level.

Set the reference level to 670mV. (center voltage reference)

LPC ON/OFF and LD ON/OFF control is performed with commands.

The laser power control limit can also be switched between ±50% and ±17% with commands.

LPC

OFF

LPCL

—

VL variable range

Approximately 1.27V

ON

±50% Approximately 1.27V ± 625mV

ON

±17% Approximately 1.27V ± 208mV

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