Table 1: Measured values to calculate power dissipation.

Drain current ID (rms) (A)On-state resistance RDS (on)     (Ω)First power dissipation PDA     (W)Ambient temperature tA (°C)Heatsink temperature tS (°C)Drain source voltage VDS (V)Second power dissipation PDB (W)Percentage difference (%)

Changing ambient temperature
1.000.400.4025.425.80.400.400%
2.000.652.6029.331.91.372.74−5%
3.000.887.9036.544.42.798.386%
4.001.2720.3046.867.15.5122.038%

Constant ambient temperature
1.001.341.3424.625.90.400.40−234%
2.001.837.3024.631.91.372.74167%
3.002.1619.4124.644.02.798.38132%
4.002.6241.8924.666.55.5122.0390%