Patent ID: 6037754
Filing Date: 2000-03-14
Classification: H02M

Abstract:
A power supply circuit for producing a direct current output voltage from an input direct current voltage comprising:first and second power input terminals for receiving the input voltage thereacross;an inductor having a first terminal coupled to the first power input terminal and having an output terminal;a power switch having a first terminal coupled to the second power input terminal and having an output terminal coupled to the inductor output terminal, the power switch being responsive to a closing switching signal for coupling the inductor output terminal to the second power input terminal thereby causing the magnitude of a current through the inductor to increase, the power switch being further responsive to a opening switching signal for uncoupling the inductor output terminal from the second power input terminal thereby causing the magnitude of a current through the inductor to decrease;energy storage means having a first terminal and having an output terminal, the first terminal being coupled to the first inductor terminal, the output terminal being coupled to the inductor output terminal for receiving and storing energy transmitted from the inductor to the energy storage means; anda support circuit coupled to the power switch, the support circuit capable of producing switching signals in such a way that they are applied to the power switch, the support circuit including inductor current sensing means for sensing a magnitude of the inductor current and a durations ratio, the durations ratio equaling a fall time duration of a recent decrease of the inductor current divided by a rise time duration of a recent increase of the inductor current, the support circuit including means for computing a maximum inductor current from at least the durations ratio, the support circuit including current comparing means for comparing the inductor current magnitude to reference currents and for producing a closing switching signal when the inductor current magnitude becomes not greater than a zero reference current that approximately equals a zero current and an opening switching signal when the inductor current magnitude becomes not less than a maximum reference current that approximately equals the maximum inductor current;thereby a direct current output voltage being formed across the terminals of the energy storage means.