XT55 AVL User’s
Guide
Confidential/Released
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XT55_avl_ug_V03
Page 37 of 37
28.06.2004
Figure 13 shows a typical example of a portable AVL application set.
Power will be supplied from an integrated Li-Ion battery pack. The charging control is
integrated in the GSM part of the XT55 module and can be used for the entire module, see
[2] for details. The headset jack is assigned to audio interface 1 of the XT55 module. The
MICP2 and MICN2 lines are intended for feeding a microphone.
Switch on /off procedure
The GSM part of the XT55 module can be powered on by pressing the ON/OFF key. The
ignition line (IGT) goes low level via the pnp transistor. During the start-up procedure the
VDD line output goes active high and the low drop regulator will be switched on. This causes
the GPS part of the XT55 module to start-up.
When pressing the ON/OFF key during operation the XT55 module will be switched off safely
using the internally activated AT^SMSO command.
NOTE: No warranty can be given for the example above because the functionality and the
compliance with regional regulations are depending in a great amount on the used electronic
components and the application layout.
Power supply ratings can be found in Table 3. For further details refer to [2]
Table 3: Average supply current without antenna
Parameter
Description
Conditions
Typ
Unit
I
GPS_VCC
Average supply
current
Continuous mode (without
antenna feeding on
GPS_VCC_RF)
80
mA
Please note that the stated current values are depending on the used mode of the module
