Ublox LEA-6, Руководство по интеграции

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LEA-6 / NEO-6 / MAX-6 - Hardware Integration Manual
UBX-14054794 Production Information Design-in
Page 20 of 85
Check Power Supply Requirements and Schematic:
 Is the power supply within the specified range? (See data sheet.)
 Is the voltage
VDDUSB
within the specified range?
 Compare the peak current consumption of your u-blox 6 module (~70 mA) with the specification of the
power supply.

GPS receivers require a stable power supply, avoid ripple on VCC (<50 mVpp)
 For low power applications using Power Save and backup modes, ensure that the power supply or low ESR
capacitors at the module input can deliver the required current/charge for switching from backup mode to
normal operation. In certain situations charging the internal capacitors in the core domain can result in a
significant instantaneous current draw.
Backup Battery
 For achieving a minimal Time To First Fix (TTFF) in Hotstart or a Warmstart, connect a backup battery to
V_BCKP.
 Time information is a requirement for AssistNow Offline, AssistNow Autonomous and when in Power Save
Mode with update period longer than 10 s.
Antenna
 The total noise figure should be well below 3 dB.

If a patch antenna is the preferred antenna, choose a patch of at least 15x15x4 mm. For smaller antennas
an LNA with a noise figure <2 dB is recommended. To optimize TTFF make use of u-blox’ free A-GPS
services AssistNow Online and AssistNow Offline.
 Make sure the antenna is not placed close to noisy parts of the circuitry. (e.g. micro-controller, display, etc.)
 For active antennas add a 10

resistor in front of V_ANT
6
input for short circuit protection or use the
antenna supervisor circuitry.

To optimize performance in environments with out-band jamming sources, use an additional SAW filter.
For information on ESD protection for patch antennas and removable antennas, see section 3.3.4 and if
you use GPS for design in combination with GSM or other radio, then check sections 3.3.6 to 3.3.8.
For more information dealing with interference issues see the GPS Antenna Application Note [5] .
Schematic
 If required, does your schematic allow using different module variants?

Don’t drive RESET_N high!
 Don’t drive configuration pins high, they already have internal pull-ups.
 Plan the use of 2nd interface (Testpoints on UART, DDC or USB) for firmware updates or as a service
connector.
Layout optimizations ( Section 2.5 )
 Is the GPS module placed according to the recommendation in section 2.5.2?
 Has the Grounding concept been followed? (See section 2.5.3.)
 Has the micro strip been kept as short as possible?
 Add a ground plane underneath the GPS module to reduce interference.

For improved shielding, add as many vias as possible around the micro strip, around the serial
communication lines, underneath the GPS module etc.
 Have appropriate EOS/ESD/EMI protection measures been included? (See section 3.3.) This is especially
important for designs including 2G, 3G modules.
6 Only available with LEA-6 modules