Sferalabs Iono Pi Max Series User Manual page 60

Thermal considerations for Iono Pi
The Raspberry Pi Compute Module draws power and generates heat proportionally to
CPU and GPU load.
The Iono Pi Max main regulator, battery charger and VSO regulator also generate a
substantial heat proportionally to the total amount of current that has to be supplied to the
Pi and, if present, external devices.
The thermal behaviour of Iono Pi Max is dynamic and affected by operating conditions and
the external environment temperature.
The Raspberry Pi CPU has the ability to throttle down its clock speed once a certain core
temperature is reached. This prevents CPU overheating, also limiting the temperature
inside the enclosure, when the CPU load is high for a significant amount of time.
A small internal fan, directly overhead the voltage regulators area of the main circuit board,
plays an important role keeping the temperature inside the enclosure to reasonable levels,
even under heavy electrical load conditions. The fan starts only when temperature or
power draw exceeds preset levels. See the "Internal fan and temperature sensors" chapter
above for additional details.
The following charts show the thermal behaviour of Iono Pi Max in different conditions, in a
typical installation with the device under test installed in a standard, not ventilated DIN
cabinet:
• 30C and 45C ambient temperature (the ambient temperature is measured inside the DIN
cabinet, so it is the actual air temperature surrounding the Iono Pi Max enclosure)
• Raspberry Pi 3 Compute Module 3 B+
• Low electrical load versus high electrical load conditions.
60 Iono Pi Max User Guide