10 Application and Hints
10.1 Minimum Configuration
Please refer to chapter “
3.1 Minimum Configuration” for details. As outlined there,
for optimized start-up behavior it is strongly recommended to add a battery back-up
circuit (see chapter “
10.6 Battery Back-up”).
10.2 External Antenna Status Adaptation
This chapter shall give assistance in designing a circuit for detecting if an antenna
is connected to the module. The information about the antenna status can be de-
rived from the ANTSTAT signal generated by this circuit. The examples use values
for components that roughly result in the following ANTSTAT output:
•
Logic low when:
Iant < 9mA
•
Logic high when:
9mA > Iant < 16mA
•
Logic low when:
Iant > 16mA
10.2.1 External Antenna Sensor
The following circuit is a proposal on how you can feed an antenna with 3.3V and
provide an output for the ANTSTAT pin. The value of the components may need an
adaptation in the final application. For example, the input current of the chosen
comparator goes into that equation. The thresholds defined in this circuit are quite
close to the ones described above. Their value is determined by resistors R4, R5,
and R3.
We strongly recommend simulating and testing the GPS receiver integrated in your
product design before implementing the finalized product in the appropriate market
application.
V1.5 – Dec-09
User’s Manual
Page 28 of 37
