u-blox LEA-5 Series Hardware Manual page 44

The open circuit detection circuit uses the current flow to detect an open circuit in the antenna. The threshold
current can be calculated using Equation 1.
Antenna
R2
Supply in
R1
C1
T1
PNP
R3
Figure 37: Schematic of open circuit detection variant B (for exact pin orientation see data sheet)
References Value
C1 2.2 µF
C2 100 nF
FB1 600
R1
15
R2
10
R3, R4
10 k
R5
33 k
T1, T2
Table 10: Active antenna supervisor, bill of material
Status reporting
At startup and on every change of the antenna supervisor configuration the u-blox 5 GPS/GALILEO module will
output a NMEA ($GPTXT) or UBX (INF-NOTICE) message with the internal status of the antenna supervisor
(disabled, short detection only, enabled).
None, one or several of the strings below are part of this message to inform about the status of the active
antenna supervisor circuitry (e.g. "ANTSUPERV= AC SD OD PdoS").
12 Transistors from other suppliers with comparable electrical characteristics may be used.
GPS.G5-MS5-09027-A2
Active Antenna
FB1
V_ANT
C2
T2
PNP
R4 R5
ADDET_N
Analog GND
Tolerance Description
Capacitor, X7R, min 10 V
10%
Capacitor, X7R, min 10 V
10%
Ferrite Bead
Resistor, min 0.063 W
10%
Resistor, min 0.250 W
10%
Resistor, min 0.063 W
10%
Resistor, min 0.063 W
10%
PNP Transistor BC856B
LEA-5, NEO-5, TIM-5H - Hardware Integration Manual
GND
RF_IN
GND
V_ANT
VCC_RF
AADET_N
u-blox 5 module
Released
Remarks
e.g. Murata BLM18HD601SN1
e.g. Philips Semiconductors 12
Design-in
Page 44 of 68