ZED-F9K-Integration manual
Figure 40: RF ESD precautions
4.6.2 EOS precautions
Electrical overstress (EOS) usually describes situations when the maximum input power exceeds
the maximum specified ratings. EOS failure can happen if RF emitters are close to a GNSS receiver
or its antenna. EOS causes damage to the chip structures. If the RF_IN is damaged by EOS, it is hard
to determine whether the chip structures have been damaged by ESD or EOS.
EOS protection measures as shown in the figure below are recommended for any designs combining
wireless communication transceivers (e.g. GSM, GPRS) and GNSS in the same design or in close
proximity.
Figure 41: Active antenna EOS protection
4.6.3 Safety precautions
The ZED-F9K must be supplied by an external limited power source in compliance with the clause
2.5 of the standard IEC 60950-1. In addition to external limited power source, only Separated or
Safety Extra-Low Voltage (SELV) circuits are to be connected to the module including interfaces and
antennas.
For more information about SELV circuits see section 2.2 in Safety standard IEC 60950-1.
4.7 Electromagnetic interference on I/O lines
Any I/O signal line with a length greater than approximately 3 mm can act as an antenna and may
pick up arbitrary RF signals transferring them as noise into the receiver. This specifically applies to
unshielded lines, in which the corresponding GND layer is remote or missing entirely, and lines close
to the edges of the printed circuit board.
If, for example, a cellular signal radiates into an unshielded high-impedance line, it is possible to
generate noise in the order of volts and not only distort receiver operation but also damage it
UBX-20046189 - R01
4 Design Page 82 of 105
C1-Public Early production information
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