LISA-U1 series - System Integration Manual
3G.G2-HW-10002-3
Preliminary
Features description
Page 116 of 125
3.10.2
Threshold Definitions
When the application of wireless module operates at extreme temperatures with Smart Temperature Supervisor
enabled, the user should note that outside the valid temperature range the device will automatically shut down
as described above.
The input for the algorithm is always the temperature measured within the wireless module (Ti, internal). This
value can be higher than the working ambient temperature (Ta, ambient), since (for example) during
transmission at maximum power a significant fraction of DC input power is dissipated as heat This behavior is
partially compensated by the definition of the upper shutdown threshold (t
+2
) that is slightly higher than the
declared environmental temperature limit.
The temperature thresholds are defined according the Table 41.
Symbol
Parameter
Temperature
Remarks
t
-2
Low temperature shutdown
–40 °C
Equal to the absolute minimum temperature rating for the wireless
module (the lower limit of the extended temperature range)
t
-1
Low temperature warning
–30 °C
10°C above t
-2
t
+1
High temperature warning
+77 °C
20°C below t
+2
. The higher warning area for upper range ensures
that any countermeasures used to limit the thermal heating will
become effective, even considering some thermal inertia of the
complete assembly.
t
+2
High temperature shutdown
+97 °C
Equal to the internal temperature Ti measured in the worst case
operating condition at typical supply voltage when the ambient
temperature Ta in the reference setup (*) equals the absolute
maximum temperature rating (upper limit of the extended
temperature range)
(*) LISA-U1 module mounted on a 90 mm x 70 mm x 1.46 mm 4-Layers PCB with a high coverage of copper within climatic chamber
Table 41: thresholds definition for Smart Temperature Supervisor on the LISA-U1 series modules
The sensor measures board temperature inside the shields, which can differ from ambient temperature.
