Patent ID: RE40352

Claim:
A switch mode power supply, comprising: a switching transistor having a load path formed by a first main connection and a second main connection, said first main connection and said second main connection for receiving a voltage applied thereto, said switching transistor including a semiconductor body with a semiconductor layer of a first conductance type forming a drift area ; a load connected in series with said load path of said switching transistor; a continuous drain region of a second conductance type incorporated into said drift area semiconductor layer and connected to said first main connection; a continuous source region of the second conductance type incorporated into said drift area semiconductor layer and connected to said second main connection; a reverse-biased pn-junction produced by an interaction between said semiconductor body layer and said continuous drain region and between said semiconductor body layer and said continuous source region; said reverse-biased pn-junction having a large inner voltage-dependent surface area that is variable as a function of the voltage applied to said first main connection and said second main connection; when the gate to source voltage applied is 10 V, said switching transistor is characterized by a first product of a switch-on resistance R on and a gate charge Q gtot , the first product given by: R on *Q gtot /10 V≦2.5 ns; and when the drain to source voltage applied is 400 V, said switching transistor is characterized by a second product of the switch-on resistance R on and energy E ds stored in a drain-source capacitance, the second product given by R on *E ds ≦1.6 V 2 μs.