Ublox SARA-R5 Series, Руководство по системной интеграции

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SARA-R5 series - System integration manual
UBX-19041356 - R04 Design-in Page 50 of 118
C1-Public
2.2.1.9 Additional guidelines for VCC supply circuit design
To reduce voltage drops, use a low impedance power source. The series resistance of the supply lines
(connected to the modules’ VCC and GND pins) on the application board and battery pack should also
be considered and minimized: cabling and routing must be as short as possible to minimize losses.
Three pins are allocated to VCC supply connection. Several pins are designated for GND connection.
It is recommended to correctly connect all of them to supply the module minimizing series resistance.
To reduce voltage ripple and noise, improving RF performance especially if the application device
integrates an internal antenna, place the following bypass capacitors near the
VCC pins:
• 68 pF capacitor with self-resonant frequency in the 700/800/900 MHz range (e.g. Murata
GRM1555C1H680J), to filter EMI in the low cellular frequency bands
• 15 pF capacitor with self-resonant frequency in the 1700/1800/1900 MHz range (as Murata
GRM1555C1H150J), to filter EMI in the high cellular frequency bands
• 10 nF capacitor (e.g. Murata GRM155R71C103K), to filter digital logic noise from clocks and data
• 100 nF capacitor (e.g. Murata GRM155R61C104K), to filter digital logic noise from clocks and data
An additional capacitor is recommended to avoid undershoot and overshoot at the start and at the
end of RF transmission:
•
10

F capacitor, or greater capacitor, with low ESR (e.g. Murata GRM188R60J106ME47)
An additional series ferrite bead may be provided for additional RF noise filtering, in particular if the
application device integrates an internal antenna:
•
Ferrite bead specifically designed for EMI / noise suppression in the GHz frequency band (e.g. the
Murata BLM18EG221SN1), placed as close as possible to the
VCC input pins of the module,
implementing the circuit described in Figure 28 , to filter out EMI in all the cellular bands
C5
GND plane
VCC line
Capacitor with
SRF ~900 MHz
C1 C3 C4
FB1
Ferrite bead
for GHz noise
C2
C1
GND
C2 C4
SARA-R5 series
52
VCC
53
VCC
51
VCC
3V8
C5
FB1
C3
Capacitor with
SRF ~1900 MHz
SARA
Figure 28: Suggested design to reduce ripple / noise on VCC, in particular suitable when using an integrated antenna
Reference Description Part number - Manufacturer
C1 68 pF capacitor ceramic C0G 0402 5% 50 V GRM1555C1H680JA16 - Murata
C2 15 pF capacitor ceramic C0G 0402 5% 50 V GRM1555C1H150JB01 - Murata
C3 10 nF capacitor ceramic X7R 0402 10% 16 V GRT155R71C103KE01 - Murata
C4 100 nF capacitor ceramic X7R 0402 10% 16 V GCM155R71C104KA55 - Murata
C5
10

F capacitor ceramic X5R 0603 20% 6.3 V
GRM188R60J106ME47 - Murata
FB1 Chip Ferrite bead EMI filter for GHz band noise
220
 at 100 MHz, 260  at 1 GHz, 2000 mA
BLM18EG221SN1 - Murata
Table 15: Suggested components to reduce ripple / noise on VCC
☞
The necessity of each part depends on the specific design, but it may be in particular suitable to
provide all the parts described in
Figure 28 / Table 15 if the application device integrates an internal
antenna.