LG F1200 Service Manual page 27

3. TECHNICAL BRIEF
D. Analog S/W
Analog S/W selects voice path or music (MP3/AAC) path according to the control signal of
MIDI_EN from DBB (calypso plus). Two voice signals (HSOL, HSOR) are voice signal from
ABB (Syren). And two music signals are from the headphone amplifier which amplify the
music signals from MP3/AAC decoder (uPD9993). The output signals are connected to ear-
set through the 12-pin ear-jack.
HSOL
HSOR
9LD
8
T1
6
T2
3
ND
9
ND
E. Power Supply Circuits for uPD9993
The uPD9993 needs three power supply 1.5V for digital core, 2.8V for analog core, 2.8V for
external interfaces. In F1200, the power supplies for analog core and external interfaces are
combined with one supply. So dual LDO is used power supply for uPD9993. "1.5V_CORE" is
for digital core of uPD9993 and "2.8V_DSP" is for analog core and external interfaces of
uPD9993. The LDO is controlled with REGEN signal from ABB (SYREN).
C568
NA
C569 C539
NA 1u
U505
MAX4684EBC
L502
C4 C2
NO1 IN1
100nH
L501
A4 A2
NO2 IN2
100nH
C1 C3
NC1 COM1
A1 A3
NC2 COM2
R519
NA
Figure 15. Analog S/W Circuits
U500
1
VIN
2
EN1
3
EN2
4
BYP
5
C509 NC1
0.01u
Figure 16. LDO Circuits for uPD9993
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MIDI_EN
C526 10u
C527 10u
C528 C529
47p 47p
MIC2211-FMBML
10
VOUT1
9
VOUT2
8
NC3 C507
2.2u
7
NC2
6
GND
11
BGND
HSBIAS
HSMIC
R511
33
R510
33
C508
2.2u