u-blox LEA-5T User Manual

LEA-5, NEO-5, TIM-5H - Hardware Integration Manual
GPS.G5-MS5-09027-A2 Released Design-in
Page 43 of 68
Firmware supports an active antenna supervisor circuit, which is connected to the pin AADET_N. An example of
an open circuit detection circuit is shown in Figure 36 and Figure 37. High on AADET_N means that an external
antenna is not connected.
Short Circuit Detection (SCD)
A short circuit in the active antenna pulls V_ANT to ground. This is detected inside the u-blox 5 module and the
antenna supply voltage will be immediately shut down.
Antenna short detection (SCD) and control is enabled by default.
Open Circuit Detection (OCD)
R1 R2
R3
u-blox 5 Module
GND
RF_IN
GND
V_ANT
VCC_RF
AADET_N
u1
Figure 36: Schematic of open circuit detection variant A (for exact pin orientation see data sheet)
References
Value
Tolerance
Description
Remarks
R1
10
5%
Resistor, min 0.063 W
R2
560
5%
Resistor
R3
100 k
5%
Resistor
u1
LT6000
Rail to Rail Op Amp
Table 9: Active antenna supervisor, bill of material
RFVcc
R
RR
R
I _
1
32
2
Equation 1: Calculation of threshold current for open circuit detection
If the antenna supply voltage is not derived from Vcc_RF, do not exceed the maximum voltage rating of
AADET_N.

u-blox LEA-5T Specifications

General

Brand	u-blox
Model	LEA-5T
Category	GPS
Language	English