SARA-N2 / N3 series - System integration manual
UBX-17005143 - R13
Design-in
Page 38 of 95
C1-Public
2.2.1.6
Additional guidelines for VCC supply circuit design
To reduce voltage drops, use a low impedance power source. The resistance of the power supply lines
(connected to the
VCC
and
GND
pins of the module) on the application board and battery pack should
also be considered and minimized: cabling and routing must be as short as possible to minimize power
losses.
Three pins are allocated for
VCC
supply. Another twenty pins are designated for
GND
connection. It is
highly recommended to properly connect all the
VCC
pins and all the
GND
pins to supply the module,
to minimize series resistance losses.
To reduce voltage noise, especially if the application device integrates an internal antenna, place the
following bypass capacitors near the
VCC
pins:
•
56 pF 0402 capacitor with self-resonant frequency in 700/800/900 MHz range (e.g. Murata
GRM1555C1E560J) to filter transmission EMI in the NB-IoT bands 28 / 20 / 5 / 8
•
15 pF 0402 capacitor with self-resonant frequency in 1800/1900 MHz range (e.g. Murata
GRM1555C1E150J) to filter transmission EMI in the NB-IoT band 3
•
10 nF capacitor (e.g. Murata GRM155R71C103K) to filter noise from clocks and data sources
•
100 nF capacitor (e.g. Murata GRM155R61C104K) to filter noise from clocks and data sources
•
100
µ
F low ESR capacitor (e.g. Kemet T520B107M006ATE015) to avoid voltage undershoot and
overshoot at the start and end of a RF transmit burst, stabilizing the voltage profile at max Tx
power, recommended in particular for noise sensitive applications
For devices integrating an internal antenna, it is recommended to provide space to allocate all the
components shown in
C1
GND
C2
SARA-N2/N3
52
VCC
53
VCC
51
VCC
3V6
C5
VCC line
Capacitor with
SRF ~900 MHz
C4
C2
C3
C1
C5
SARA
C4
C3
Capacitor with
SRF ~1800 MHz
+
Figure 18: Suggested schematic and layout design for the VCC line, highly recommended when using an integrated antenna
Reference
Description
Part number - Manufacturer
C1
56 pF capacitor ceramic C0G 0402
GRT1555C1E560JA02 - Murata
C2
15 pF capacitor ceramic C0G 0402
GJM1555C1H150JB01 - Murata
C3
10 nF capacitor ceramic X7R 0402
GRT155R71C103KE01 - Murata
C4
100 nF capacitor ceramic X7R 0402
GCM155R71C104KA55 - Murata
C5
100
µ
F capacitor tantalum 15m
T520B107M006ATE015 - Kemet
Table 13: Suggested components to reduce noise on VCC
☞
ESD sensitivity rating of
VCC
pins is 1 kV (HBM according to JESD22-A114). Higher protection level
can be required if the line is externally accessible on the application board, e.g. if accessible battery
connector is directly connected to
VCC
pins. Higher protection level can be achieved by mounting
an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) close to accessible point.
