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HUAWEI MG323 GSM M2M Module
Hardware Guide
Description of the Application Interfaces
Issue 04 (2011-08-22)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
25
Figure 3-12 External circuit for 32 Ω handsets/16 Ω headsets
Table 3-7 Required speaker power for 32 Ω handsets/16 Ω headsets
Speaker Load
Total Harmonic Distortion
Power (Typical)
32 Ω (handset)
THD < 0.1%
91 mW
32 Ω (handset)
THD < 1%
96 mW
16 Ω (headset)
THD < 0.1%
127 mW
16 Ω (headset)
THD < 1%
144 mW
The specifications listed in Table 3-7 are based on the specified working temperature
of the module.
3.8.3 Microphone Interface
A microphone with an equivalent load of 2.2 kΩ is recommended, because both the
pull-up resistor and the pull-down resistor of the two types of differential signal lines
for the microphone are 1 kΩ. It is recommended that ESD components and 33 pF
capacitors be added to the interface to reduce radio frequency interference.