SIM Tech SIMCom SIM900-DS, Проектирование аппаратного обеспечения

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