Apalis/Colibri T30 Temperature Monitoring
The Colibri/Apalis T30 modules come with an LM95245 temperature monitoring chip. The LM95245 monitors two temperatures
- Local: temperature of the temperature sensor chip
- Remote: temperature of the T30 silicon
Beside the i2c bus, the LM95245 features two outputs which get active if any temperature rises above a programmable threshold:
- nOS: This is a simple digital IO which can be monitored by the operating system. The reaction on this signal is depending on the software.
- nT_CRIT: This output is hard wired to the power supply and turns off the CPU power rails if it becomes active.
After power-up, all temperature thresholds are at their default values:
| LM95245 output | Remote (T30) | Local (LM9245) | Unit |
|---|---|---|---|
| nT_CRIT | 110 | 85 | °C |
| nOS | 85 | 85 | °C |
These threshold temperatures are adjusted while booting the operating system. The default values remain active until the operating system has booted. At very high temperatures, the thermal monitor may shut down the power supplies, before the OS is able to increase the nT_CRIT temperature threshold.
General Consideration Regarding the Thermal Behavior
- The power consumption and therefore the generated heat is heavily dependent on the currently running software. Therefore it is not possible to provide a generic guideline which cooling solution is required at which ambient temperature.
- If you need the full CPU/graphics performance over a long period of time we recommend adding a cooling solution.
- If you only use the peak performance for a short time period heat dissipation is less of a problem because the advanced power management reduces power consumption when full performance is not required.
- The SoC silicon temperature has a significant impact on the power consumption, which amplifies the effect of any cooling solution. In general the more effective the thermal solution is at dissipating heat the more performance you can get out of the Colibri/Apalis T30 Module.
Linux
The Linux Operating System changes the default temperature thresholds as follows in order to pass regular consumer temperature range testing:
| LM95245 output | Remote (T30) | Local (LM9245) | Unit |
|---|---|---|---|
| nT_CRIT | 115 | 95 | °C |
| nOS | 85 | 95 | °C |
When powering off the module, the nT_CRIT stored value will be deleted and the default value will be used, which would prevent a module turning on if the LM95245 detects it has a higher temperature than 85°C. You can prevent this with a proper cooling solution or by simply leaving the module cool to a temperature lower than 85°C.
Dynamic Voltage and Frequency Switching
The Colibri/Apalis T30 software incorporates DVFS (Dynamic Voltage and Frequency Switching) and Thermal Throttling which enables the system to continuously adjust operating frequency and voltage in response to changes in workload and temperature. This allows the Colibri/Apalis T30 to deliver higher performance at lower average power consumption compared to other solutions.
Commercial Operating Temperature Range
The full commercial temperature range of 0°C up to 70°C is supported.
Industrial Operating Temperature Range
NVIDIA officially only supports a fixed 900MHz operation point for the IT graded T30 SoCs at a CPU voltage level of 1.007V for slow parts and 0.916V for fast parts (meaning silicon process variation called speedo setting by NVIDIA) and a core voltage level of 1.25V. The GPU is to be run at 484Mhz and the DDR RAM at 625Mhz. Alternatively the regular cores can be shut down completely and the shadow core can operate at a fixed 450Mhz frequency.
Windows CE
Eboot changes the default temperature thresholds as follows in order to pass regular consumer temperature range testing:
| LM95245 output | Remote (T30) | Local (LM9245) | Unit |
|---|---|---|---|
| nT_CRIT | 115 | 120 | °C |
| nOS | 85 | 120 | °C |
When powering off the module, the nT_CRIT stored value will be deleted and the default value will be used, which would prevent a module turning on if the LM95245 detects it has a higher temperature than 85°C. You can prevent this with a proper cooling solution or by simply leaving the module cool to a temperature lower than 85°C.
There is an API to read the actual local and remote temperatures from a user application. You can check an example at SoC Temperature Readout (WinCE).
Dynamic Voltage and Frequency Switching
The Colibri/Apalis T30 software incorporates DVFS (Dynamic Voltage and Frequency Switching) which enables the system to continuously adjust operating frequency and voltage in response to changes in workload. This allows the Colibri/Apalis T30 to deliver higher performance at lower average power consumption compared to other solutions.
Commercial Operating Temperature Range
The full commercial temperature range of 0°C up to 70°C is supported.
Industrial Operating Temperature Range
NVIDIA officially only supports a fixed 900MHz operation point for the IT graded T30 SoCs at a CPU voltage level of 1.007V for slow parts and 0.916V for fast parts (meaning silicon process variation called speedo setting by NVIDIA) and a core voltage level of 1.25V. The GPU is to be run at 484Mhz and the DDR RAM at 625Mhz. Alternatively the regular cores can be shut down completely and the shadow core can operate at a fixed 450Mhz frequency. However, under Windows CE we use a similar DVFS throttling as for the commercial temperature range modules, in order to minimize the power dissipation.