LG KG290 - Answering and Managing Calls

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3. TECHNICAL BRIEF
5. Microphone
The main microphone is soldered to the main PCB. The audio signal is passed to AIN1P(#P16),
AIN1N(#R16), AIN2P(#P15) and AIN2N(#R15) pins of AD6721.
The voltage supply 2V5_VMIC is output from AD6721. The voltage supply 2V5_JACK is output from
BH25FB1WHFV (Low Drop Output). The VIN1 and VIN2 signals are A/D converted by the Voiceband
ADC part of AD6721. The digitized speech is passed to the DSP section for processing(coding,
interleaving etc.) The Microphone interface is shown in Figure 4.
LGE Internal Use Only Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
C228 0.1u
C219
39p
R231 100ohm
39p
C223
R221
1K
C215
10u
C235 39p
VA204
EVL5M02200
R227
2.2K
100ohmR232
EVL5M02200
VA203
39p
2V5_VMIC
C234
R234
2.2K
C222
39p
OB4-15L42-C33L
1
2
MIC200
MIC_P
MIC_N
3K
R225
1.5KR229
R228 0.1u
C224
27p
0.1uC220
2V8_VMEM
10u
C226C225
27p
AUXIN
AUXIP
Figure 5. Microphone(main & aux)