Reference Circuit Design For Microphone Interfaces - Quectel SC262R Series Hardware Design

MIC_BIAS2 155
MIC3_P 148
MIC_BIAS1 147
EAR_P 8
EAR_N 9
SPK_P 10
SPK_N 11
HPH_R 136
HPH_REF 137
HPH_L 138
HS_DET 139
⚫
The module offers three audio input channels, including three single-ended channels.
⚫
The output voltage range of the two MIC_BIAS is programmable between 1.6 V and 2.85 V, and the
maximum output current is 3 mA.
⚫
The earpiece interface uses differential output.
⚫
The loudspeaker interface uses differential output as well. The output channel is available with a
Class-D amplifier whose output power is 1362 mW when the load is 8 Ω.
⚫
The headphone interface features stereo left and right channel output, and supports headphone
insertion detect.

3.22.1. Reference Circuit Design for Microphone Interfaces

Module
Figure 24: Reference Circuit Design for ECM Microphone Interface
SC262R_Series_Hardware_Design
AO Bias voltage output for microphone 2
AI Microphone input for channel 2 (+)
AO Bias voltage output for microphone 1
AO Earpiece output (+)
AO Earpiece output (-)
AO Speaker output (+)
AO Speaker output (-)
AO Headphone right channel output
AO Headphone reference ground
AO Headphone left channel output
AI Headset hot-plug detect
MIC1_P
MIC_GND
D1
R1
0R
R2
R3
0R
C1
33 pF
0R
Smart Module Series
V = 1.6–2.85 V
O
V = 1.6–2.85 V
O
High level by default.
ECM MIC
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