Query on "Continuous power dissipation" in data sheet

DC-DC Power Converters
#1

Hi Team,

In all MPS DS the Continuous power dissipation @ 25deg C is mentioned in ABSOLUTE MAXIMUM RATINGS (1) column. So what is the mentioned power dissipation? is it only IC’s or IC with all components like Inductor, Capacitor, Resistors etc…? I have tried to calculate IC & all losses i.e Psw, Pcond, Pic, PL and total loss around 40% of mentioned in DS. Kindly guide correctly if I am doing wrong calculations.

Exp: MP1476, Continuous power dissipation (TA = +25°C) is 2.2W
calculations:
PFET 309.9319167 mW (PQ1=(Vo/Vin)(Io^2 + ∆I^2/12)(RDSON1) + PQ2=(1-Vo/Vin)(Io^2 + ∆I^2/12)(RDSON2)
PL 72 mW (PL=Io^2 x RDCR)
PIQ 2.28 mW (PIQ=VinxIq)
Psw 30 mW (Psw=VinxIoxFsw(Qgs2+Qgd)/Ig)
Ptotal = 0.411W only.

#2

The issue is die temperature if it is too hot the reliability is compromised. The temperature of the nearby inductor contributes to the die temp but for the sake of this line I expect the chip was thermally remote from other sources of heat. If you want more dissipation increase the switching frequency, increase the input voltage and increase the load.

If you want the chip to be hotter, then use less thin traces and less than the minimum suggested thermal mitigation efforts.

If you work backwards from the thermal resistance and the maximum die temp you will likely find the maximum dissipation drops out.