LG MG180C Service Manual page 40

3.5.15. Audio Circuit
MIC
MICBIAS
15p
C233
C234
MICP
220n
C240
MICN
220n
Microphone circuits
When a call is established, MICBIAS signal goes up to '2.5V' in the MG180c. IOTA(ABB) provides bot
h 2.0V and 2.5V for MICBIAS to circuit designer. VA202, VA203 are employed to enhance ESD
immunity.
R215
1K C231
47p
(1608)
R217
1K
C236
47p
R218
C241 1K
15p
Figure 19. Microphone system
3. H/W Circuit Description
R216
2.4K
C232
4.7u
C235
NA
C237 C238
10p 47p
C242 R220
NA
1K
- 39 -
VA202
OB4-15L42-C33L
C239
2
27p
1
MIC200
VA203