Smart LTE Module Series
SC66 Hardware Design
SC66_Hardware_Design 85 / 139
The module offers three audio input channels, including one differential input pair and two
single-ended channels. The three sets of MICs are integrated with internal bias voltage.
The output voltage range of MIC_BIAS is programmable between 1.6V and 2.9V, and the maximum
output current is 3mA.
The earpiece interface uses differential output.
The loudspeaker interface uses differential output as well. The output channel is available with a
Class-D amp
lifier whose maximum output power is 1.5W when the load is 8Ω.
The headphone interface features stereo left and right channel output, and headphone insertion
detection function is supported.
3.22.1. Reference Circuit Design for Microphone Interface
MIC1_P
ECM-
Type
R2
R1
Module
D1
MIC1_N
33pF
0R
0R
R
3
0
R
Figure 30: Reference Circuit Design for Analog ECM-type Microphone
EAR_P
53
AO
Earpiece output (+)
EAR_M
52
AO
Earpiece output (-)
SPK_P
55
AO
Speaker output (+)
SPK_M
54
AO
Speaker output (-)
HPH_R
51
AO
Headphone right channel output
HPH_REF
50
AI
Headphone reference ground
It should be connected
to main GND
HPH_L
49
AO
Headphone left channel output
HS_DET
48
AI
Headset insertion detection
High level by default.
