D.c.-to-d.c. converter having an improved surge suppressor

Year	Description
2000	Invention patented by Akihiro Uchida on December 10th, 2000. Abstract: A d.c.-to-d.c. converter of the kind having a step-up or step-down transformer with a primary to be connected to a d.c. power supply via an electronic switch, and a secondary to be connected to a load via a smoothing and rectifying circuit. The voltage being applied to the load is detected and fed back to a switch control circuit whereby the switch is controlled to keep constant the converter output voltage. Connected in parallel with the transformer primary, a surge suppressor circuit has a serial connection of a surge-absorbing capacitor and a rectifying diode and a resistor for absorbing a surge developing across the transformer primary winding each time the switch is turned off. In order to attenuate the high-frequency ringing of the voltage across the switch due to the leakage inductance and stray capacitance of the transformer primary and to the stray capacitance of the switch, the reverse recovery time of the diode of the surge suppressor circuit is made longer than half the cycle of the ringing voltage and shorter than the expected minimum non-conducting period of the switch.
Source: selected by the editor from original sources.

Invention: D.c.-to-d.c. converter having an improved surge suppressor