SLVSFV6B August 2022 – October 2023 DRV8962
PRODUCTION DATA
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 22.2 °C/W for the DDW package.
Assuming 25°C ambient temperature, the junction temperature for the DDW package is calculated as shown below -
For more accurate calculation, consider the dependency of on-resistance of FETs with device junction temperature shown in the Typical Operating Characteristics section.
For example,
At 101.8 °C junction temperature, the on-resistance will likely increase by a factor of 1.35 compared to the on-resistance at 25 °C.
The initial estimate of conduction loss was 2.65 W.
New estimate of conduction loss will therefore be 2.65 W x 1.35 = 3.58 W.
New estimate of the total power loss will accordingly be 4.388 W.
New estimate of junction temperature for the DDW package will be 122.4 °C.
Further iterations are unlikely to increase the junction temperature estimate by significant amount.
When using the DDV package, if a heat sink with less than 4 °C/W thermal resistance is chosen, the junction to ambient thermal resistance can be lower than 5 °C/W. The initial estimate of the junction temperature with the DDV package in this application will therefore be -
As the DDV package results in low thermal resistance, it can deliver 10 A full-scale current.