UMTS/HSPA Module Series
UC20 EVB User Guide
UC20_EVB_User_Guide Confidential / Released 16 / 30
PCM_IN
PCM_OUT
PCM_SYNC
PCM_CLK
I2C_SCL
I2C_SDA
CODEC
NAU8814
UMTS Module
1.8V
4
.7
K
4
.7
K
BCLK
MCLK
FS
DACIN
ADCOUT
SCLK
SDIN
M
IC
_
B
IA
S
MIC_BIAS
MIC+
MIC-
SPKOUT-
UC20 EVB
R
C
Figure 8: Audio Codec Circuit
3.3.1. Loud Speaker (J402)
Figure 9 shows the loud speaker circuit with external audio Class-D amplifier. And the name of the J402
pins has been marked on the EVB.
SPKOUT-
Differential layout
Amplifier
circuit
1nF
1nF
75pF
75pF
Close to speaker
GND
GND
ESD
ESD
Codec
75pF
FB
FB
C1
C2
J402
U401
NAU8814
Figure 9: Loud Speaker Circuit
3.3.2. Earphone (J404)
An earphone can be used in audio interface J404. Figure 10 shows the circuit of audio interface J404 for
earphone:
Quectel
Condidential
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