Alpc (Automatic Laser Power Control) Circuit; Description Of Circuit - LG GCE-8240B Service Manual

1. ALPC (Automatic Laser Power Control) Circuit

1-1. ALPC Loop Circuit
3.3V
R422
C456
R423 IC403
C455
R247
R252
C445
WR/RE
3
5 IC205
TC7W08FV
WGATE
6
24

DESCRIPTION OF CIRCUIT

IC401 CXA2638R
(Read)
RFPDG
20dB/26dB
R1
20K
FPDO
S/H
100
20K
R5
R2
20K
GND
RFPDSH
32
Typ.
10mV/step
sbit
SHOUT
99
RLDON
ERCNT
SHOUT
(Write)
R8
AUX
20K
62
WRITEG WFPDG
R3
20K
Gain
S/H
adj.
20K
R6
R4
20K
FVREF
1
WREFSE
WFPDSH
31 GND
L:B.HOLD
HOLDSW
H:A.SAMPLE
45
Typ. GND
R429
10mV/step
8 bit
WREFSE
WLDON
48
166
WGATE
188
180
MPXOUT
(testmode)
VRDCN
R7
98
20K
8
R16 C1
R9
5K
97
R11
VRDC
A:OFF
10K
B:ON
RREFSE
GND
H:RREF
L:OPEN
VRDC
GND
DAC
96
R13
25.8K
RREF
GND
VWDCN
94
APCCSW
R18
95
S3.
R10 B APCCSW
5K
24
VWDC
A
R12
A:OFF
10K
B:ON
GND
S/H
A B
MPXOUT
(testmode)
WREF
DAC 92
R14
H:OPEN
25.8K
L:WREF
HOLDTC
WREF
90
GND
Typ. GND ODREF
91
DAC
10mV/step
R15
7 bit
25.8K
ODREF
GND
IC301 MICOM
7
WR/RE
IC201
OTI-9797
22
FPDVC
19 FPDO
R410
25
VRDC
R17
C433
GND
C3
R408
R19
C432
GND
D401
13
18
C4
IC402
17
DAC
4
5
16
15
R321
R322
SCLK
64 65
60
DACS
EFM1 183
EFM2
184
PN401
P/U
26 VWDC
R447
C454
R426
27 VWDC2
C443
R427
30 WE1
31 WE2