Sony Ericsson GR64 - Manual (Page 52)

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5.9.2 Auxiliary Audio from Mobile Station (AUXO)
AUXO is a single-ended auxiliary analogue audio output from the wireless modem
and may be used to drive a speaker or an earpiece. The interface has an internal
100nF coupling capacitor; a load of 10kohm will provide a near full-scale output
capability between 300 to 4300 Hz.
The table below shows the audio signal levels for AUXO.
Parameter Conditions Min Typ Max Unit
Output voltage full scale RL =10kΩ 670 750 840 mVrms
Frequency response -3dB cut-off (RL =10kΩ) 225 Hz
5.9.3 Microphone Signals (MICIP, MICIN)
MICP and MICN are balanced differential microphone input pins. These inputs are
compatible with an electret microphone. The microphone contains a FET buffer with
an open drain output, which is supplied with at 2.4V ±10% relative to ground by the
wireless modem as shown below.
Figure 5.9-1 Microphone connections to the wireless modem
The input low-noise amplifier stage is constructed out of standard low-noise op
amps. External resistors set the gain of this stage.
The input gain is scaled by the input resistors to be around 18, which provides
optimal performance for many standard types of electret microphones. The module
provides a microphone bias at 2.4V, and can supply at least 1mA of current.