Integration Manual
Table Of Contents
- Document information
- Contents
- 1 System description
- 1.1 Overview
- 1.2 Architecture
- 1.3 Pin-out
- 1.4 Operating modes
- 1.5 Supply interfaces
- 1.5.1 Module supply input (VCC)
- 1.5.1.1 VCC supply requirements
- 1.5.1.2 VCC current consumption in LTE connected mode
- 1.5.1.3 VCC current consumption in 2G connected mode
- 1.5.1.4 VCC current consumption in ultra low power deep sleep mode
- 1.5.1.5 VCC current consumption in low power idle mode
- 1.5.1.6 VCC current consumption in active mode (PSM / low power disabled)
- 1.5.2 Generic digital interfaces supply output (V_INT)
- 1.5.1 Module supply input (VCC)
- 1.6 System function interfaces
- 1.7 Antenna interfaces
- 1.8 SIM interface
- 1.9 Data communication interfaces
- 1.10 Audio
- 1.11 General Purpose Input/Output
- 1.12 GNSS peripheral input output
- 1.13 Reserved pins (RSVD)
- 2 Design-in
- 2.1 Overview
- 2.2 Supply interfaces
- 2.2.1 Module supply (VCC)
- 2.2.1.1 General guidelines for VCC supply circuit selection and design
- 2.2.1.2 Guidelines for VCC supply circuit design using a switching regulator
- 2.2.1.3 Guidelines for VCC supply circuit design using LDO linear regulator
- 2.2.1.4 Guidelines for VCC supply circuit design using a rechargeable battery
- 2.2.1.5 Guidelines for VCC supply circuit design using a primary battery
- 2.2.1.6 Guidelines for external battery charging circuit
- 2.2.1.7 Guidelines for external charging and power path management circuit
- 2.2.1.8 Guidelines for particular VCC supply circuit design for SARA-R4x2
- 2.2.1.9 Guidelines for removing VCC supply
- 2.2.1.10 Additional guidelines for VCC supply circuit design
- 2.2.1.11 Guidelines for VCC supply layout design
- 2.2.1.12 Guidelines for grounding layout design
- 2.2.2 Generic digital interfaces supply output (V_INT)
- 2.2.1 Module supply (VCC)
- 2.3 System functions interfaces
- 2.4 Antenna interfaces
- 2.5 SIM interface
- 2.6 Data communication interfaces
- 2.7 Audio
- 2.8 General Purpose Input/Output
- 2.9 GNSS peripheral input output
- 2.10 Reserved pins (RSVD)
- 2.11 Module placement
- 2.12 Module footprint and paste mask
- 2.13 Thermal guidelines
- 2.14 Schematic for SARA-R4 series module integration
- 2.15 Design-in checklist
- 3 Handling and soldering
- 4 Approvals
- 4.1 Product certification approval overview
- 4.2 US Federal Communications Commission notice
- 4.3 Innovation, Science, Economic Development Canada notice
- 4.4 European Conformance CE mark
- 4.5 National Communication Commission Taiwan
- 4.6 ANATEL Brazil
- 4.7 Australian Conformance
- 4.8 GITEKI Japan
- 4.9 KC South Korea
- 5 Product testing
- Appendix
- A Migration between SARA modules
- B Glossary
- Related documentation
- Revision history
- Contact
SARA-R4 series - System integration manual
UBX-16029218 - R20 Design-in Page 69 of 129
C1-Public
2.4.3 GNSS antenna RF interface (ANT_GNSS)
☞ The GNSS antenna RF interface is supported by SARA-R422M8S modules only.
☞ For additional information and guidelines regarding the GNSS design, see the u-blox SARA-R4 /
SARA-R5 positioning implementation application note [20].
The antenna and its placement are critical system factors for accurate GNSS reception. Use of a
ground plane will minimize the effects of ground reflections and enhance the antenna efficiency. A
good allowance for ground plane size is typically in the area of 50 x 50 to 70 x 70 mm
2
. The smaller the
electrical size of the plane, the narrower the reachable bandwidth and the lower the radiation
efficiency. Exercise care with rover vehicles that emit RF energy from motors etc. as interference may
extend into the GNSS band and couple into the GNSS antenna suppressing the wanted signal. For
more details about GNSS antennas, see also the u-blox GNSS antennas application note [21].
Since SARA-R422M8S modules already include an internal SAW filter followed by an additional LNA
before the u-blox M8 GNSS chipset (as illustrated in Figure 4), they are optimized to work with passive
or active antennas without requiring additional external circuitry.
2.4.3.1 Guidelines for applications with a passive antenna
If a GNSS passive antenna with high gain and good sky view is used, together with a short 50 line
between antenna and receiver, and no jamming sources affect the GNSS passive antenna, the circuit
illustrated in Figure 40 can be used. This provides the minimum BoM cost and minimum board space.
SARA-R422M8S
31
ANT_GNSS
GND
Figure 40: Minimum circuit with GNSS passive antenna
If the connection between the module and antenna incurs additional losses (e.g. antenna placed far
away from the module, small ground plane for a patch antenna) or improved jamming immunity is
needed due to strong out-of-band jammers close to the GNSS antenna (e.g. the cellular antenna is
close to the GNSS antenna), consider adding an external SAW filter (see Table 26 for possible suitable
examples) close to the GNSS passive antenna, followed by an external LNA (see Table 27 for possible
suitable examples), as illustrated in Figure 41, provided that SARA-R422M8S modules already include
dedicated internal SAW filter followed by an LNA before the u-blox M8 GNSS chipset (as illustrated in
Figure 4), so that additional external SAW and LNA are not required for most of the applications (see
section 2.4.4 for further details and design-in guidelines regarding Cellular / GNSS RF coexistence).
☞ An external LNA with related external SAW filter are only required if the GNSS antenna is far away
(more than 10 cm) from the GNSS RF input of the module. In that case, the SAW and the LNA
must be placed close to the passive antenna.