GPS receiver A1080-A
10 Applications and Hints
10.1 Minimum Configuration
Please refer to chapter 3.1 Minimum Configuration for details. In addition, for opti-
mized start-up behavior it is strongly recommended to add a battery back-up circuit
(see chapter 3.4)!
10.2 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 Antennas with Different Current Draw
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
comperator 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 your realized version before using
it. In any case, it is the responsibility of the designer to test and verify the implemen-
tation.
Page 22 of 31
User’s Manual
V2.3 - 07/07
