u-blox SARA-G3 Series, System Integration Manual

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SARA-G3 series - System Integration Manual
UBX-13000995 - R06 Objective Specification Design-in
Page 111 of 218
Reference Description Remarks
C1 100 nF Capacitor Ceramic X7R 0402 10% 16
V GRM155R61A104KA01 - Murata
U1 Low Power Clock Oscillator 32.768 kHz OV-7604-C7 - Micro Crystal or SG-3040LC - EPSON
TOYOCOM
Table 21: Example of components for the EXT32K application circuit
The two different solutions described in
Figure 35Figure 35 and Figure 36Figure 36 are alternative and
mutually exclusive: only one of the two proposed solutions must be implemented according to the required
current consumption figures for the idle-mode (for the detailed characteristics refer to the
SARA-G3 series
Data Sheet [1]).
As additional solution, alternative and mutually exclusive to the two described in
Figure 35Figure 35 and
Figure 36Figure 36 , a proper 32 kHz signal can be provided to the EXT32K input by the used
application processor, if capable.
The
EXT32K input and the 32K_OUT output are not available on SARA-G350 modules since the internal
oscillator generates the 32 kHz RTC reference clock.
ESD sensitivity rating of the EXT32K input pin and the 32K_OUT output pin is 1 kV (Human Body
Model according to JESD22-A114). Higher protection level can be required if the line is externally
accessible on the application board. Higher protection level can be achieved by mounting an ESD
protection (e.g. EPCOS CA05P4S14THSG varistor array) close to accessible point.
If the customer application does not require the low power idle-mode and the RTC functions, the
EXT32K input pin and the 32K_OUT output pin can be left not connected.
2.2.3.2 Guidelines for EXT32K and 32K_OUT layout design
The EXT32K input pin and the 32K_OUT output pin require accurate layout design: avoid injecting noise
on these pins as it may affect the stability of the RTC timing reference.