SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R26
System description
Page 86 of 217
1.13.10
Smart temperature management
Not supported by SARA-G300 and SARA-G310 modules.
Cellular modules – independently from the specific model – always have a well-defined operating temperature
range. This range should be respected to guarantee full device functionality and long life span.
Nevertheless there are environmental conditions that can affect operating temperature, e.g. if the device is
located near a heating/cooling source, if there is/is not air circulating, etc.
The module itself can also influence the environmental conditions; such as when it is transmitting at full power.
In this case its temperature increases very quickly and can raise the temperature nearby.
The best solution is always to properly design the system where the module is integrated. Nevertheless an extra
check/security mechanism embedded into the module is a good solution to prevent operation of the device
outside of the specified range.
Smart Temperature Supervisor (STS)
The Smart Temperature Supervisor is activated and configured by a dedicated AT+USTS command. See the
u-blox AT Commands Manual
[3] for more details. An URC indication is provided once the feature is enabled
and at the module power on.
The cellular module measures the internal temperature (Ti) and its value is compared with predefined thresholds
to identify the actual working temperature range.
Temperature measurement is done inside the module: the measured value could be different from the
environmental temperature (Ta).
Warning
area
t
-1
t
+1
t
+2
t
-2
Valid temperature range
Safe
area
Dangerous
area
Dangerous
area
Warning
area
Figure 35: Temperature range and limits
The entire temperature range is divided into sub-regions by limits (see Figure 35) named t
-2
, t
-1
, t
+1
and t
+2
.
Within the first limit, (t
-1
< Ti < t
+1
), the cellular module is in the normal working range, the Safe Area
In the Warning Area, (t
-2
< Ti < t
.1
) or (t
+1
< Ti < t
+2
), the cellular module is still inside the valid temperature
range, but the measured temperature is approaching the limit (upper or lower). The module sends a
warning to the user (through the active AT communication interface), which can take, if possible, the
necessary actions to return to a safer temperature range or simply ignore the indication. The module is still in
a valid and good working condition
Outside the valid temperature range, (Ti < t
-2
) or (Ti > t
+2
), the device is working outside the specified range
and represents a dangerous working condition. This condition is indicated and the device shuts down to
avoid damage
On SARA-G340 and SARA-G350 modules, for security reasons the shutdown is suspended in case an
emergency call is in progress. In this case the device switches off at call termination.
On SARA-U2 series modules, in case an emergency call is in progress, the shutdown occurs 3 seconds
after the "dangerous working condition" URC has been issued.
The user can decide at anytime to enable/disable the Smart Temperature Supervisor feature. If the feature
is disabled there is no embedded protection against disallowed temperature conditions.
