Originally Posted by

**Luca**
Rdson normalized means that the value of the axis Y which is the multiplier to apply to the Rdson dependently from X-axis, the temperature.

For IRFP460 MOSFET this means that at about 23°C, the multiplier is 1 (y-axis), so that the final Rdson will be (1 x nominal value), which means 1 x 0.27 = 0.27 ohms.

For example, at about 70°C, the multiplier is 1.5, then Rdson will be 1.5 x 0.27 = 0.4 ohms.

An important thing to notice is that the nominal value of 0.27 ohms are declared with the same Vgs voltage of 10V, and this is not always true in a mosfet datasheet ...

Tipically 23°C can be assumed like "room temperature" and, last but not least, the graph is about *Tj = T Junction* of the power FET, this means inside the mosfet...

I hope this can help with the concept of Rdson, regards

Luca