Switched mode power supply
First Claim
1. In a switched mode power supply having a pair of supply voltage terminals, a pair of transistors having their emitter-collector paths connected in series to said terminals, first and second capacitors connected in series between said terminals, a series circuit of a load circuit and an inductor connected between the junction of said first and second capacitors and the junction of said emitter-collector paths, and a source of control pulses connected to the basis of said transistors;
- the improvement wherein said source of control pulses is connected to render said transistors conductive on alternate pulses, and further comprising a third capacitor connected in parallel with said load circuit and forming a series resonant circuit in combination with said inductor at a frequency substantially equal to the pulse repetition frequency of said control pulses of said source of pulses, whereby back e.m.f. of said inductor at the time of switching off of each of said transistors reduces the emitter-collector voltage of the other transistor at the switch on time of said other transistor.
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Accused Products
Abstract
A switched mode power supply includes a pair of capacitors serially connected across a supply input and a pair of switching transistors serially connected across the supply input. The output load circuit is connected between the junction of the capacitors and the junction of the transistors by way of a series conductor. A capacitor is connected in parallel with the load and a further capacitor, which may consitute stray capacitance, is also connected between the junctions of the transistors and the junctions of the capacitors.
96 Citations
6 Claims
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1. In a switched mode power supply having a pair of supply voltage terminals, a pair of transistors having their emitter-collector paths connected in series to said terminals, first and second capacitors connected in series between said terminals, a series circuit of a load circuit and an inductor connected between the junction of said first and second capacitors and the junction of said emitter-collector paths, and a source of control pulses connected to the basis of said transistors;
- the improvement wherein said source of control pulses is connected to render said transistors conductive on alternate pulses, and further comprising a third capacitor connected in parallel with said load circuit and forming a series resonant circuit in combination with said inductor at a frequency substantially equal to the pulse repetition frequency of said control pulses of said source of pulses, whereby back e.m.f. of said inductor at the time of switching off of each of said transistors reduces the emitter-collector voltage of the other transistor at the switch on time of said other transistor.
- View Dependent Claims (2, 3, 4, 5, 6)
Specification