Description Of Circuit; Alpc (Automatic Laser Power Control) - LG GDR-8162B Service Manual

1. ALPC (Automatic laser power control)

1-1. ALPC Circuit Constitution
Dual laser power control for DVD and CD are provided.
The laser ON for DVD or CD can be selected by ¡ LDSEL¡– and the lasers ON/OFF are controlled by ¡ LDOFF¡– .
Laser power for DVD and CD can be programmable by ¡ LDPWR 0,1¡–
MD
2
LDPWR0.1
MD
4
LDRWR0.1
DVD-RAM 4.7G : about 0.23V
DVD-RAM 2.6G : about 0.18V
DVD-ROM : about 0.18V
CD : about 0.19V
18

DESCRIPTION OF CIRCUIT

IC101
For DVD
LDOFF
LDSEL
For CD
ALPC (Automatic laser plower control)
3
Q110
5
Q110
CD
Q102,
5V
DVD-RAM 4.7G : about 0.77V
DVD-RAM 2.6G : about 0.68V
DVD-ROM : about 0.68V
CD : about 0.7V
P/U
25
21
19
Q104
20 22