Only For Training And Service Purposes - LG KP270 Service Manual

3. TECHNICAL BRIEF
3.13.1 Audio amplifier
KP270 use external AMP(MAX9877).
MAX9877 combines a high efficiency Class D audio power amplifier with a stereo Class AB
capacitorless Direct Drive headphone amplifier.
MAX9877 delivers up to 725mV from a 3.7V supply into an 8ohm load with 87% efficiency to extend
battery life.
AUDIO AMP
RADIO_OUT_R
RADIO_OUT_L
HS_R
HS_L
REC_P
REC_N
LGE Internal Use Only
C403
C407 1u
A4
C1N
C411 1u A5
C1P
C412 1u D1
INA2
C415 1u
D2
INA1
C416 1u C1
INB2
C420 1u C2
INB1
B2
C423 C424 BIAS
39p 39p
B3
SDA SDA
C3
SCL SCL
R405 2.2
D4
RXIN+
R406 2.2 B4
RXIN-
C429
C430 C431 1u
39p 39p
[Figure 3.13.1-1] Audio AMP circuit diagram
- 46 -
VBAT
C404
1u 4.7u
A1
HPR
A2
HPL
C417
U401
39p
MAX9877AEWP_TG45
D5
OUT+
B5
OUT-
C427
39p
Copyright © 2008 LG Electronics. Inc. All right reserved.
HSO_R
HSO_L
C418
39p
SPK_RCV_P
SPK_RCV_N
C428
39p

Only for training and service purposes