Switch mode power supply with reduced switching losses
First Claim
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1. 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 and connected to said first main connection;
a continuous source region of the second conductance type incorporated into said drift area and connected to said second main connection;
a reverse-biased pn-junction produced by an interaction between said semiconductor body and said continuous drain region and between said semiconductor body 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 voltage applied is 10 V, said switching transistor is characterized by a first product of a switch-on resistance Ron and a gate charge Qgtot, the first product given by;
Ron*Qgtot/10 V≦
2.5 ns; and
when the voltage applied is 400 V, said switching transistor is characterized by a second product of the switch-on resistance Ron and energy Eds stored in a drain-source capacitance, the second product given by Ron*Eds≦
1.6 V2 μ
s.
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Abstract
The invention relates to a switching transistor presenting reduced switching losses. In the switching transistor, output capacitance is very high when drain/source voltages are low. As the drain/source voltage increases, the capacitance falls to such low values that the energy stored in the transistor becomes very low.
87 Citations
5 Claims
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1. A switch mode power supply, comprising:
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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 and connected to said first main connection;
a continuous source region of the second conductance type incorporated into said drift area and connected to said second main connection;
a reverse-biased pn-junction produced by an interaction between said semiconductor body and said continuous drain region and between said semiconductor body 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 voltage applied is 10 V, said switching transistor is characterized by a first product of a switch-on resistance Ron and a gate charge Qgtot, the first product given by;
Ron*Qgtot/10 V≦
2.5 ns; and
when the voltage applied is 400 V, said switching transistor is characterized by a second product of the switch-on resistance Ron and energy Eds stored in a drain-source capacitance, the second product given by Ron*Eds≦
1.6 V2 μ
s.- View Dependent Claims (2, 3, 4, 5)
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Specification