Inrush protection circuit

A rectifier power supply system in combination with a filtering capacitor, said power supply system comprising inrush current circuitry, including:

• a current-limiting resistor placed in series with the filtering capacitor;
• and
• a MOSFET switching device placed in parallel with said current-limiting resistor to bypass current around the current-limiting resistor during normal steady state circuit operation, said MOSFET being open only during an initial interval of time when said capacitor is being charged, said MOSFET being controlled by a timing network of resistors and capacitors contained in said rectifier power supply system, said MOSFET closing after said initial interval of time and remaining closed until removal of substantially all current from said MOSFET.

A switch-mode supply system in combination with a filtering capacitor, said switch-mode supply system comprising inrush current circuitry, including:

• a current-limiting resistor placed in series with the filtering capacitor;
• and
• a MOSFET switching device placed in parallel with said current-limiting resistor to bypass current around the current-limiting resistor during normal steady state circuit operation, said MOSFET being open only during an initial interval of time when said capacitor is being charged, said MOSFET being controlled by a timing network of resistors and capacitors contained in said switch-mode supply system, said MOSFET closing after said initial interval of time and remaining closed until removal of substantially all current from said MOSFET.

An electronic ballast, used for energizing fluorescent or gas discharge lighting, in combination with a filtering capacitor, said electronic ballast comprising inrush current circuitry, including:

• a current-limiting resistor placed in series with the filtering capacitor;
• and
• a MOSFET switching device placed in parallel with said current-limiting resistor to bypass current around the current-limiting resistor during normal steady state circuit operation, said MOSFET being open only during an initial interval of time when said capacitor is being charged, said MOSFET being controlled by a timing network of resistors and capacitors contained in said electronic ballast, said MOSFET closing after said initial interval of time and remaining closed until removal of substantially all current from said MOSFET.