Design care must be taken to make sure that the thermal ratings of the DRV835x are not violated during normal operation of the device. The is especially critical in higher voltage and higher ambient operation applications where power dissipation or the device ambient temperature are increased.
To determine the temperature of the device in dual supply operation, first the internal power dissipation must be calculated. The internal power dissipation has four primary components:
The value of PVM can be calculated by referring to the datasheet parameter for IVM current and Equation 47.
The value of PBUCK can be calculated with the buck output voltage (VVCC), buck output current (IVCC), and by referring to the typical characteristic curve for efficiency (η) in the LM5008A data sheet.
The total power dissipation is then calculated by summing the four components as shown in Equation 50.
Note that the information in the Thermal Information is based off of a standardized test metric for package and PCB thermal dissipation. The actual values may vary based on the actual PCB design used in the application.