User's Guide

LE920A4 HW User Guide Hardware Interfaces
Doc#: 1VV0301261 Audio Interface
Rev. 4.7.1 Page 82 of 124 2019-11-21
PAD Signal I/O Function Type Comment
E2 EAR2_MT+ AO Earphone Signal Output 2, phase + Analog
D1 EAR2_MT- AO Earphone Signal Output 2, phase - Analog
C2 MIC2_MT+ AI Mic Signal Input 2, phase + Analog
B1 MIC2_MT- AI Mic Signal Input 2, phase - Analog
For more details, refer to Ref 5: Digital Voice Interface_Application_Note.
WARNING:
The analog audio implementation uses an internal CODEC (inside the
module). The internal codec uses the same signals as the external digital
audio interface.
Therefore, applications that use analog audio (that is, the codec inside the
module) must make sure that the digital audio interface is either not
connected, set to Hi-Z, or set to ‘input’ to Host application.
8.6.2. Analog Audio Characteristics
The tables below list the analog audio characteristics of the audio codec included in the
module.
8.6.2.1. Analog Inputs Characteristics
Table 34: Microphone Input Characteristics (Valid for both MIC1 and MIC2)
Parameter Conditions Min Typ Max
Input
impedance
30 kΩ 50 kΩ
Max
microphone
input
Mic Digital Gain = 0dB
Mic Analog Gain = 1dBf = 1 kHz
Differential mode
450mV
P-P
THD + N Mic Gain = 0dB
f = 1 kHz
Mic Input = 1V
P-P,
Differential
mode
-80 dB