User Guide

GE9
GE9GE9
GE910 Hardware User Guide
10 Hardware User Guide10 Hardware User Guide
10 Hardware User Guide
1vv0300962 Rev.4 2012-06-25
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 51 of 73
Mod. 0805 2011-07 Rev.2
10.4.2. Output Lines
EAR/Line-out Output
Differential line coupling
Direct connection (V
DC
=1.3÷1.6V)
Single-ended line coupling
One EAR terminal connected via a
DC-block capacitor, the other one left
open
output load resistance ≥ 8 Ω
internal output resistance 4 Ω (typ.)
signal bandwidth 250÷3400Hz
(@ -3dB with default filter)
max. differential output voltage 1120mV
pp
@3.14dBm0 (*)
differential output voltage 550mV
rms
@0dBm0 (*)
volume increment 2dB per step
volume steps 0..10
(*) in default condition: AT+CLVL=10, AT#HFRECG=0
WARNING: When in Single Ended configuration, the unused output line must be left open: if
this constraint is not respected, the output stage will be damaged.
TIP : We suggest driving the load differentially; this kills all the common mode noises (click
and pop, for example), the output swing will double (+6dB) and the big output coupling
capacitor will be avoided.
However if particular OEM application needs, also a Single Ended (S.E) circuitry can be
implemented. The OEM circuitry shall be designed to reduce the common mode noise typically
generated by the return path of the big currents.
In order to get the maximum power output from the device, the resistance of the tracks has to be
negligible in comparison to the load.