Design care must be taken to make sure that the thermal ratings of the DRV8353M 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 single supply operation, first the power internal power dissipation must be calculated. The internal power dissipation has four primary components:

• VCP charge pump power dissipation (P_VCP)
• VGLS low-side regulator power dissipation (P_VGLS)
• VM device nominal power dissipation (P_VM)
• VIN buck regulator power dissipation (P_BUCK)

The values of P_VCP and P_VGLS can be approximated by referring to Section 14.2.1.2.1 to first determine I_VCP and I_VGLS and then referring to Equation 20 and Equation 21.

The value of P_VM can be calculated by referring to the data sheet parameter for I_VM current and Equation 22.

where

• P_O = V_VCC × I_VCC

The value of P_BUCK can be calculated with the buck output voltage (V_VCC), buck output current (I_VCC), 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 24.

Lastly, the device junction temperature can be estimate by referring to Section 10 and Equation 25.

The information in Section 10 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.