Specifications

Cinterion
®
ALAS5V Hardware Interface Description
2.3 GNSS Antenna Interface
67

ALAS5V_HID_v00.030a 2019-03-20
Confidential / Preliminary
Page 57 of 124
Figure 23 shows a sample circuit realizing ESD protection for a passive GNSS antenna. Con-
necting the input ANT_GNSS_DC to GND prevents ESD from coupling into the module.
Figure 23: ESD protection for passive GNSS antenna
2.3.1 GNSS Antenna Diagnostic
GNSS antenna diagnosis does require an external detection circuit. The antenna DC supply
current can be measured via ADC5_IN. The ADC5_IN input voltage (Ug) may be generated by
a sample circuit shown in Figure 22. The circuit allows to check the presence and the connec-
tion status of an active GNSS antenna. Passive GNSS antennas cannot be detected. There-
fore, GNSS antenna detection is only available in active GNSS antenna mode.
Having enabled the active GNSS antenna mode the presence and connection status of an ac-
tive GNSS antenna can be checked. The following table lists sample current ranges for possi-
ble antenna states as well as sample voltage ranges as possible decision thresholds to
distinguish between the antenna connection states.
Table 17: Sample ranges of the GNSS antenna diagnostic measurements and their possible meaning
Antenna connection status Current ranges (I
S
)
1
1. Please note that the mA ranges 1.4mA...2.2mA and 20mA...30mAare tolerance ranges. The decision
threshold should be defined within these ranges.
Voltage ranges (U
G
)
Antenna not connected <1.4mA
Decision threshold 59mV ±20%
Antenna connected 2.2mA...20mA
Decision threshold 825mV ±20%
Antenna short circuited to ground >30mA
GNSS antenna detection is not possible because
GNSS antenna power supply is switched off.
--
GNSS_EN
ANT_GNSS
Passive
GNSS
antenna
10nH
100nF
To GNSS
receiver
Module
SMT interface
ANT_GNSS_DC
(Optional)
ESD
protection
0R
Not used