JAJSP91B October 2023 – May 2024 TPSM86837 , TPSM86838
PRODUCTION DATA
The power module integrates the main power dissipating elements, the power switches and magnetics, all into one package, which enables smaller design size and simplifies the development. Therefore, in addition to the IC losses, the heat generated from the inductor direct current resistance (DCR) and core losses add to the total power dissipated in the package. Under the same operating conditions as the discrete counterparts (which have an external inductor), the module has the challenge of dissipating more heat through a smaller surface area. There is a constraint on the maximum output current that modules can deliver at higher operating ambient temperatures due to limitations in maximum temperature ratings for both the inductor and IC.
The temperature rise of module can be calculated by using efficiency and EVM effective RθJA. Equation 11 calculates the power loss from the data sheet efficiency curves:
Where ƞ is the application conditions efficiency. As an example, Figure 7-2 shows the efficiency curve at 25°C for the 24Vin, 1.8Vout, 800kHz condition. At 8A load, with nearly 81% efficiency, Equation 11 calculates the power loss as 3.378W. Multiplying by the EVM effective RθJA 24 °C/W gives a temperature rise of 81°C.
The maximum temperature rating for TPSM8683x is 150°C. Subtracting this temperature rise from the 150°C maximum temperature results in a maximum ambient temperature of 69°C. Consider operation within this ambient temperature.