Hardware+Design V1.07

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to the ATC manual.
3.4.1 Pin Description
Table 10: Pin description
Audio channel Pin name Pin No. Function
MIC1P 23 MIC positive input
MIC1N 24 MIC negative input
EAR1P 26 Receiver positive output
Normal
EAR1N 25 Receiver negative output
MIC1P 23 MIC positive input
MIC1N 24 MIC negative input
SPK_P 22 Loudspeaker positive output
Hand-free
SPK_N 21 Loudspeaker negative output
Table 11: MIC input characteristics
Parameter Min Typ Max Unit
Working Voltage - 1.8 - V
Working Current 0.07 0.4 1 mA
External Microphone Load Resistance 1.2 2.2 k Ohms
Table 12: Audio output characteristics
Parameter Min Typ Max Unit
Load resistance 27 32 - Ohm Normal
(EAR_P,EAR_N)
Differential
Output power - 50 - mW
Table 13: Speaker output characteristics
Parameter Min Typ Max Unit
Quiescent Current - 2.5 4 mA
Load resistance - 8 - Ohm
Output power(1KHz) - 500 - mW
3.4.2 Design Guide
There are three audio channels in SIM5320，including speaker output , receiver output and microphone
input.
SPEAKER circuit in SIM5320 is a Class-D amplifier, optional EMI filter is shown in the following figure;
these components (two ferrite beads and two capacitors) can reduce electromagnetic interference. If used,
they should be located beside SPK_P and SPK_N pins. Considerable current flows in the channels, so
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