SIM Tech SIMCom SIM800C User Manual

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SIM800C_Hardware_Design_V1.00 31 2014-10-30
Figure 28: UART1_RI behaviour as a caller
4.7. Audio Interfaces
SIM800C provides an analog input (MICP; MICN), which could be used for electret microphone. The module
also provides an analog output (SPKP; SPKN).
Table 12: Audio interface definition
SPKP/SPKN output can directly drive 32Ω receiver, SIM800C internal has class-AB audio amplifier, the
following table is class-AB performance:
Table 13: Performance of audio amplifier
Conditions
Class-AB AMP
4.2V 8Ω THD+N=1%
0.87W
3.4V 8Ω THD+N=1%
0.53W
4.2V 8Ω THD+N=10%
1.08W
3.4V 8Ω THD+N=10%
0.65W
SPKP/SPKN output can directly drive 8Ω speaker.
AT command “AT+CMIC” is used to adjust the input gain level of microphone. AT command “AT+SIDET”
is used to set the side-tone level. In addition, AT command “AT+CLVL” is used to adjust the output gain level.
For more details, please refer to document [1].
In order to improve audio performance, the following reference circuits are recommended. The audio signals
have to be layout according to differential signal layout rules as shown in following figures.
4.7.1. Speaker Interfaces Configuration
Pin name
Pin number
Function
MICP
9
Audio input positive
MICN
10
Audio input negative
SPKP
11
Audio output positive
SPKN
12
Audio output negative

SIM Tech SIMCom SIM800C Specifications

General

Brand	SIM Tech
Model	SIMCom SIM800C
Category	Control Unit
Language	English