Rev 3.0 Aug.19
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2: General Rules for Design
This section provides rules to obtain the best performance when using the GNSS
module.
Circuit Design
Power Supply
A clean and stable power supply is required for the GNSS modules to perform
optimally. An unstable power source will significantly impact GNSS performance. To
achieve high-quality performance, the VCC ripple must be controlled under 50mVpp.
Additional considerations to stabilize power supply include:
1.
Adding a ferrite bead, power choke, or low pass filter for power noise reduction.
2.
Adding a linear regulator (LDO) is rather than a switched DC/DC power supplier
in the ripple.
3.
Using enough decoupling capacitors with the VCC for stable voltage.
Figure 2-1: Power Design for the GNSS Module
VBACKUP Backup Battery
The GNSS module has a built-in charging circuit which charges the rechargeable coin
battery.
It’s recommended that the module be provided with backup power (e.g. Li-Ion
rechargeable coin battery, super capacitor). See
for a reference design.
For information on the super capacitor reference design, please refer to
Backup power is needed to maintain RTC operation and retain Ephemeris data in
flash memory which helps the module get quicker TTFF and acquire PVT (Position,
Velocity, Time) information.