SLOSE70 December 2020 DRV8434S
For an ambient temperature of TA and total power dissipation (PTOT), the junction temperature (TJ) is calculated as -
TJ = TA + (PTOT x RθJA)
Considering a JEDEC standard 4-layer PCB, the junction-to-ambient thermal resistance (RθJA) is 29.7 °C/W for the HTSSOP package and 39 °C/W for the VQFN package.
Assuming 25°C ambient temperature, the junction temperature for the HTSSOP package is calculated as shown below -
The junction temperature for the VQFN package is calculated as shown below -