CXA1821 View Datasheet(PDF) - Sony Semiconductor
Part Name
Description
Manufacturer
CXA1821 Datasheet PDF : 13 Pages
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CXA1821M
Tracking Error Amplifier
Each signal current from the photodiodes E and F is I-V converted and input to Pins 8 and 9 via an input
resistor which determines the gain. The signal is amplified by the gain amplifier, operated by the tracking error
amplifier and then the (F-E) signal is output to Pin 13.
The E input gain can be adjusted by Pin 11.
Pin 18 can be used as a bias for LC when connected to VCC and as a bias for PD IC when left open.
I-V
I-V
GND
VC
F
150k
8
820k
E
820k
150k
9
VC
EI
10
260k
260k
VC
26k
13k 23.8k
12p
23.8k
123k
TRACKING
ERROR AMP
123k
VC
12p
18 LC/PD
TE
13
TEOUT
TRK E
GAIN
EO 22k 22k
11
APC Circuit
When the laser diode is driven with constant current, the optical output possesses large negative
temperature characteristics. Therefore, the current must be controlled with the monitor photodiode to ensure
the output remains constant. This constitutes the APC circuit. When LD ON pin is connected to VCC, APC is
ON; connected to VEE, it is OFF.
VCC
22
10µH
LD
1
PD
2
100
500
GND
1k
VCC
56k
55k
10k
VEE
10k
56k
10k
VREF
1.25V
VEE
–8–
LDON MICRO
19
COMPUTER
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