Motorola AT Commands G24-L Informações Técnicas descarregar pdf (Página 54)

Audio Interface

28 G24-L Module Hardware Description November 15, 2008

Figure 2-16 shows the microphone circuit and Table 2-7 gives the microphone specifications.

Figure 2-16: Headset Microphone Circuit

Important: The headset microphone circuit design depends on the type of microphone device.

A series capacitor is required in case a passive microphone is used, or the

application provides a separate bias voltage to an active microphone circuit.

The internal G24-L biasing circuit may also be used with an active microphone,

which corresponds to the headset microphone port specifications.

Speaker Port

The analog speaker port is the G24-L power-up default active output for voice calls and DTMF

tones. It is located at pins 67 and 69 on the G24-L interface connector, named SPKR_N and

SPKR_P respectively.

It is designed as a differential output with 32Ω impedance, but may also be used as a single-ended

output referenced to the G24-L analog ground.

The speaker output is used for both the handset and the headset audio paths.

Table 2-7:

Headset Microphone Port Specifications

Parameter Conditions Min Typ Max Unit

Input Voltage No load 2.0 V

Gain Programmable by

+MMICG

031dB

AC Input

Impedance

Freq=1Khz 1 kΩ

Bias voltage R

BIAS

= 2.0 kΩ

BIAS

< 1 mA

2.0 V

Bias Current 1 mA

1 2 ... 49 50 51 52 53 54 55 56 57 58 59 ... 105 106

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Motorola AT Commands G24-L Informações Técnicas Página 54