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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 kΩ
Internal biasing DC Characteristics 2.5 V
THD <1% at F=1KHz;
pre-amp gain = 20 dB;
PGA gain = 14 dB
15.9 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=32Ω, THD=0.1% - - 91 mW
RL=32Ω, THD=1% - - 96 mW
Output swing Voltage
(single ended)
1.1 Vpp
Normal Output
(SPK)
Output swing Voltage
(differential)
2.2 Vpp
SIM900R_Hardware Design_V1.00 27 2012-07-20