Bias power source energized by tertiary winding including hysteresis characteristic for disabling the power switch when a minimum base drive signal can no longer be maintained

摘要

A converter circuit that derives its bias power from voltage supplied by a tertiary winding including a tertiary winding voltage level responsive circuit with a hysteretic characteristic to selectively enable and disable the drive circuitry controlling the converter's power switching transistor. Should the bias voltage drop due to an output fault, the converter is operated at a subfrequency of its normal operating frequency in order to prevent operating the power switching transistor in its active region during high current conduction.