cxa2568m Sony Electronics, cxa2568m Datasheet - Page 13

• Manufacturer Part Number: cxa2568m
• Description: Rf Amplifier For Cd Players
• Manufacturer: Sony Electronics

• APC
• Laser Power Control (LPC)
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.
APC is set to ON by connecting the LD ON pin to V
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 RFO 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 670 mV. (center voltage reference)
When the reference level is changed, connect the external resistor to the AGCVTH pin (Pin 2). The
reference level can be lowered by connecting the resistor between Pin 2 and the center output voltage or
between Pin 2 and V
The AGCCONT pin (Pin 20) is used to switch the level of the laser power control circuit ; OFF, ON (laser
power limit of 40 %) and ON (laser power limit of 60 %).
The HOLD_SW pin (Pin 21) is used to switch the hold ON and OFF for the VL signal. Set this pin to ON so
as not to follow the fluctuation of the RF signal.
AGCCONT
L (V
M (VC or OPEN)
H (V
EE
CC
)
)
CC
.
OFF
LPC
ON
ON
LPC limit
40 %
60 %
—
—13—
CC
; OFF by connecting it to V
Approximately 1.27 V±350 mV
Approximately 1.27 V±570 mV
Approximately 1.27 V
VL variable range
EE
.
CXA2568M