Hands-Free Connector; External Voice Output - Logic IO RTCU MX2 turbo Technical Manual

RTCU MX2 turbo Technical Manual V2.04

Hands-free connector

The RTCU unit has a 4-pole 2.5mm jack connector for connecting a hands-free set to the built-in
GSM modem. The speaker output is amplified through the internal Class-D amplifier and is a
differential (balanced) signal. A loudspeaker of 4/8 Ω can be connected directly to the speaker
output. The microphone input is differential in order to minimize GSM (TDMA) noise. An audio
line transformer must be used to convert the signal to a single ended signal, when connected to
external equipment that does not have a differential (balanced) input. Otherwise the GSM noise
will not be suppressed / cancelled and will pass through all the way to the loudspeaker.
The microphone signal is biased internal for active microphones.
4 pin headset connector overview
Pin Name
1 Mic +
2 SPK +
3 Mic -
4 SPK -
Microphone characteristics
Parameter
Working voltage
Working current
Speaker characteristics
Parameter
Working voltage
Output power (THD+N=10%)
Please consult the RTCU IDE documentation for more information on using the Hands- free
interface.

External voice output

A voice audio output is available on X2 connector. Digitized audio can be played through this
output by the application interface. Please consult the RTCU IDE documentation for more
information about enabling the xVoice output and playing digitized voice messages.
The output is at line-out level (3Vpeak-peak), and internally shared with GSM voice line.
Logic IO ApS.
Holmboes Allé 14
8700 Horsens
Denmark
Description
Microphone positive Input
Speaker positive output
Microphone negative input
Speaker negative output
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Min. Typ.
1.65 1.8
20
Min. Typ.
3.5 3.8
0.83
Max. Unit
1.95 V
1000 µA
Max. Unit
4.2 V
2.05 W
Ph: (+45) 7625 0210
Fax: (+45) 7625 0211
Email: support@logicio.com
www.logicio.com