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→Estimating CPU junction temperature (Tj)
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==Introduction=Using the current/power monitor ===Obtaining an accurate measurement of power consumption for the CPU (required for this kind of assessment) is not easy. However, as a first estimate, you can use the current/power monitor INA226A mounted on the NaonEVB-Mid carrier board, which allows for measurement of the CPU module global absorption (we consider negligible the part due to the electronics external to the CPU). Please refer to [[NELK_Power_Management#Measurements_script]] for details on how to perform the measurement. Once you've collected the data, you can compare it with the ones that has been reported on [[Power consumption (Naon)]]. === Using a spreadsheet ===Another method for estimating the Tj is using the appropriate spreadsheet provided by TI: http://processors.wiki.ti.com/index.php/DM814x_AM387x_Power_Estimation. == Other useful tools and information == === Using the TSC2003 ===Naon module mounts the TSC2003 touch screen controller. This component allows for measurement of its case temperature, accessing its register via the I2C bus. This measurement is a value closely related to the CPU temperature. For further details, please refer to the component datasheet. === Using the PMIC ===The PMIC TPS659113 mounted on Naon provides Thermal shutdown protection and hot-die detection functions. These functions refer to the PMIC junction temperature and not to the CPU Tj, but they can be used to implement some protection/detection strategies.===Using a contactless sensor on carrier board===Another option for measuring the CPU's case temperature is the use of a contactless sensor that can be mounted on carrier board. See for example: http://www.ti.com/product/tmp006. == Analisys suggestions == * Determine the maximum reachable Tj, taking into account all your application requirements and the worst operating environment conditions* Consider the opportunity of using the OPP modes (see [[NELK Power Management]]) for CPU power consumption optimization, making sure that enough power is available for computing requirements.* Consider the opportunity of using the extended temperature range component (that has Tj_max=105°C) rather than the commercial temperature range model (Tj_max=90°C)* According to the estimated consumption, the system requirements and the maximum reachable Tj, consider using a heat sinking/cooling system.