SAM-M8Q - Hardware Integration Manual
UBX-16018358 - R05 Production Information Product handling
Page 18 of 23
GNSS positioning modules are sensitive to Electrostatic Discharge (ESD). Special precautions
are required when handling.
Electrical overstress (EOS)
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 EOS damages the RF_IN, it is hard to determine whether the chip structures
have been damaged by ESD or EOS.
EOS protection measures
For designs with GNSS positioning modules and wireless (e.g. GSM/GPRS) transceivers in close proximity,
ensure sufficient isolation between the wireless and GNSS antennas. If wireless power output causes the
specified maximum power input at the GNSS RF_IN to be exceeded, employ EOS protection measures to
prevent overstress damage.
3.3.1 Electromagnetic interference (EMI)
Electromagnetic interference (EMI) is the addition or coupling of energy originating from any RF emitting device.
This can cause a spontaneous reset of the GNSS receiver or result in unstable performance. Any unshielded
line or segment (>3 mm) connected to the GNSS receiver can effectively act as antenna and lead to EMI
disturbances or damage.
The following elements are critical regarding EMI:
Unshielded connectors (e.g. pin rows etc.)
Weakly shielded lines on PCB (e.g. on top or bottom layer and especially at the border of a PCB)
Weak GND concept (e.g. small and/or long ground line connections)
EMI protection measures are recommended when RF emitting devices are near the GNSS receiver. To minimize
the effect of EMI a robust grounding concept is essential. To achieve electromagnetic robustness follow the
standard EMI suppression techniques.
http://www.murata.com/products/emc/knowhow/index.html
http://www.murata.com/products/emc/knowhow/pdf/4to5e.pdf
Improved EMI protection can be achieved by inserting a resistor (e.g. R > 20 ), or better yet a ferrite bead
(BLM15HD102SN1) or an inductor (LQG15HS47NJ02), into any unshielded PCB lines connected to the GNSS
receiver. Place the resistor as close as possible to the GNSS receiver pin.
Alternatively, feed-thru capacitors with good GND connection can be used to protect against EMI. A selection of
feed-thru capacitors are listed in Table 4.
Intended use
In order to mitigate any performance degradation of a radio equipment under EMC disturbance, system
integration shall adopt appropriate EMC design practice and not contain cables over three meters on
signal and supply ports.
To Next Page
Loading...
Need help?
General
