User Manual

GM47/48 Technical description

BA/SEM/MS 02:0004 Rev B

3.6.2 Audio From Mobile Station (AFMS)

AFMS is the analogue audio output from the module. When it is

active, the output is derived from the PCM digital audio by the

decoder part of the CODEC. The PCM data comes from PCMI on the

system connector. It is also used as an ear-piece driver for the Portable

Hands Free accessory.

Parameter Limit

Speaker impedance

64 Ω το 1ΚΩ

AFMS Output Capacitance 2.2 µF ±10%

Levels (THD < 5 %)

Drive capability into 5 kΩ (0.3 -

3.5 kHz)

> 2.4 Vpp [TBC]

Drive capability into 1.5 kΩ (0.3 -

3.5 kHz)

> 2.2 Vpp [TBC]

Drive capability into 150 Ω (at

1kHz)

> 1.3 Vpp [TBC]

3.7 Microphone Signals

Pin Speaker signals Dir Function

53 MICP I Microphone Positive Input

54 MICN I Microphone Negative Input

MICP and MICN are the microphone-input pins. These inputs shall be

compatible with an electret microphone. The microphone contains a

FET buffer with open drain output, which must be supplied at least

+2V relative to ground.

Figure 3.3 Microphone connection to module

CCO is the source voltage that will provide the necessary drive

current for the microphone.