Integration Manual

LISA-U2 series - System Integration Manual
UBX-13001118 - R25 Features description Page 154 of 182
3.16 Smart Temperature Management
Cellular modules – independent of 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 the operating temperature, e.g. if
the device is located near a heating/cooling source, if there is/isn’t 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.
3.16.1 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 [2] for more details.
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 cellular 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 72: Temperature range and limits
The entire temperature range is divided into sub-regions by limits (see Figure 72) 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 approaches 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.
☞ For security reasons, the shutdown is suspended in case an emergency call in progress. In this
case, the device will switch off at call termination.
☞ The user can decide at any time to enable/disable the Smart Temperature Supervisor feature. If
the feature is disabled, there is no embedded protection against disallowed temperature
conditions.