Description Of Circuit; Alpc Circuit - LG BP50NB40 Service Manual

1. ALPC (Automatic Laser Power Control) Circuit
1-1. Block Diagram
S/H
S/H
1-2. ALPC (Automatic Laser Power Control) Circuit
ALPC function of IC101(MT1959H) is for the constant power control. Based on the FM(Front Monitor) in OPU, ALPC
feedback loop maintains constant power level against laser diode's temperature variation. RDAC is for Read Power control
and W1DAC is for Write Power control. VDAC is for the reference voltage of FM. Ipac, Vref, FM+, FM- are analog singal and
SEN, SDIO, SCLK are digital signal.

DESCRIPTION OF CIRCUIT

IC101 (MT1959H)
LPF
Filter
LPF
RDAC 103
5
VDAC
35
33
W1DAC
34
108
107
26
Optical
Iapc Pick-up
37
Vref
40
SEN
29
SDIO
30
SCLK
31
FM+
23
FM-
24
CN801
LDD
FM