User's Manual

SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R18 Advance Information Design-in
Page 110 of 206
The two different solutions described in Figure 53 and Figure 54 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 see the SARA-G3 series Data Sheet [1]).
As additional solution, alternative and mutually exclusive to the two described in Figure 53 and Figure 54, 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-G340 and 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.
2.3.3.2 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.