Earphone Interface Configuration; Audio Electronic Characteristics - SIM Tech SIMCom SIM900-DS Hardware Design

4.6.3

Earphone Interface Configuration

4.6.4

Audio Electronic Characteristics

Table 6: Microphone Input Characteristics
Parameter
Working Voltage
Working Current
External Microphone Load Resistance
Internal biasing DC Characteristics
Differential input THD <1% at F=1KHz; pre-amp gain = 20 dB;
voltage PGA gain = 14 dB
THD <5% at F=1KHz;pre-amp gain = 0 dB;
PGA gain = 0 dB
Table 7: Audio Output Characteristics
Parameter Conditions
RL=32Ω,THD=0.1%
Normal RL=32Ω,THD=1%
Output(SPK)
Output swing voltage (single ended)
Output swing voltage (differential)
SIM900-DS_Hardware Design_V1.00
Figure 24: Earphone reference circuit
Smart Machine Smart Decision
Min Typ
1.2 1.5
200
1.2 2.2
15.9
740
Min Typ
- 91
- 96
28
Max Unit
2.0 V
500 uA
kΩ
2.5 V
mVrms
mVrms
Max Unit
- mW
- mW
1.1 Vpp
2.2 Vpp
2013-01-20