Abstract: A controller for supplying a switching signal to a switched mode power supply, includes a sinusoidal-like wave generator, and circuitry for selectively shifting a dc level in the sinusoidal-like wave whereby a duty cycle of the sinusoidal-like wave at a predetermined threshold level, corresponding to a turn-on level of a power switch in the switched mode power supply, is effectively controlled.

Abstract: A high frequency HID ballast includes an inverter for operating the HID lamp at high frequency and an arc instability controller which detects and adjusts the operating frequency of the inverter to avoid acoustic resonance of the discharge arc. The ballast ensures that the power delivered to the lamp remains substantially constant despite variations in the gain of the inverter which occur with changes in the operating frequency. Power control is accomplished by sensing lamp power and controlling a boost converter to vary the bus voltage feeding the inverter. The boost converter is also controlled during lamp ignition, when the load provided by the HID lamp is low, to clamp the bus voltage at a predetermined level. The ballast employs universal techniques suitable for operating HID lamps of different types, wattages and manufacturers despite the occurrence of acoustic resonance/arc instabilities among these lamps over a fairly broad frequency range.

Abstract: A converter for supplying various output voltages for a television receiver includes a multi-resonant circuit, including a resonant inductor, the leakage inductance of a flyback transformer, and a charging capacitor (including the parasitic capacitance of a switching transistor). This arrangement relaxes the slope of the voltages in the converter resulting in reduced radiated EMI. In addition, the values of the inductor and the capacitor are adjusted so that the switching transistor turns on at zero voltage and zero current so that the switching transistor is less stressed and the converter is capable of high frequency operation. Finally, the switching signals applied to the switching transistor are subjected to a filter-delay to lessen the slope of the signals thereby also resulting in a reduction in the EMI radiated from the driving circuit.

Abstract: A forward converter for supplying various output voltages for a television receiver includes a multi-resonant circuit, including a resonant inductor, a charging capacitor, and the output capacitors across each secondary winding of an output transformer. This arrangement relaxes the slopes of the voltages in the converter resulting in reduced radiated EMI. In addition, the values of the inductor and the capacitors are adjusted so that a switching transistor in the forward converter turns on at zero voltage and zero current so that the switching transistor is less stressed and the converter is capable of high frequency operation. The secondary providing high voltage includes the series arrangement of two oppositely conducting diode branches, each branch including the series arrangement of a high voltage diode and a Schottky diode.