Abstract: A FET switching regulator has a FET switch which is periodically turned on to couple an unregulated DC input voltage to an output filter which develops a regulated output DC voltage. Regulation of the output DC voltage is determined by the on time or duty cycle of the FET switch. A periodic waveform is developed by a pulse-width modulator. The pulse-width modulator compares the input and output DC voltages to a reference voltage to pulse-width modulate the periodic waveform to determine the duty cycle. When the periodic waveform goes high, it triggers a first regenerative circuit which drives the gate of the FET switch into saturation within 20-30 nanoseconds. When the periodic waveform goes low, a second regenerative circuit is triggered to return the FET switch to an off state within 20-30 nanoseconds. Accordingly, the FET switch may be operated at frequencies approaching 500 kHz without excessive power losses within the FET switch in the transitory states between cutoff and saturation.

Abstract: A start circuit for a DC-DC switching converter power supply is disclosed and includes a relaxation oscillator connected to the DC voltage source for periodically generating a start pulse at a predetermined frequency. The start pulse is coupled to a power switch on the primary side of a power transformer and functions to cause the power switch to close for the duration of each start pulse. The secondary winding of the power transformer is coupled to an energy storage device such as a capacitor which stores the charge coupled across the power transformer each time a start pulse is generated. When sufficient energy has been stored in the capacitor in this manner, a circuit detects this energy level and causes the energy to be coupled to a pulse generator circuit also located on the secondary side of the power transformer.

Abstract: A current driven flyback power supply has a transistor current switch which periodically couples a primary current through the primary winding of a power transformer which is connected between a source of DC and the collector of the current switch. A current transformer has a first winding coupled between the primary winding and the collector of the current switch, and a second winding which develops a drive current proportional to the primary current. The drive current is coupled to the base of the current switch and increases proportionally with the increasing amplitude of the primary current. An electrical switch shorts the drive current to ground to turn off the current switch so that stored energy in the power transformer is coupled out through its secondary winding to an output rectifier circuit which develops the output DC voltage.

Abstract: An electronic ballast-inverter circuit for powering one or more fluorescent lamps or the like includes two identical circuits operating at different DC offsets, each circuit including a tank circuit composed of a primary winding of the power transformer and a capacitor such that each tank circuit resonates at the same frequency, and including a switching transistor connected to each tank circuit. These two transistors are operative on alternate half cycles of the sine wave generated by the inverter, so as to obtain the push-pull operation needed by the inverter. Each circuit includes a base drive current source for each transistor that is controlled by the polarity of an additional primary winding of the power transformer. For improved efficiency, the circuit is designed to be operable from an unsmoothed DC voltage source.

Abstract: An electronic ballast circuit for powering a plurality of fluorescent lamps or the like from an unsmoothed DC voltage source includes a sine wave converter operatively connected to receive said DC voltage, for generating a high frequency alternating voltage of sufficient amplitude to power said lamps. The converter comprises a tank circuit and two push-pull transistors connected thereto and a current source capacitively coupled to said tank circuit for providing base drive alternately to each transistor. A lamp filament heater current cancellation circuit reduces power drain once the lamps have turned on.

Abstract: A free-running flyback DC power supply includes a transformer having at least one primary and one secondary winding, a transistor switch in series with the primary winding for controlling when current from a source of DC power is coupled through said winding, and a rectifier circuit attached to the secondary winding for generating a DC output voltage. A conventional regulator circuit causes the transistor switch to turn off primary winding current as a function of the present value of DC output voltage. A second circuit senses excessive current in the primary winding and causes the transistor switch to turn off independently of said regulator circuit, to protect against damage to the transistor switch or transformer. A third circuit detects when the DC source voltage is below a predetermined minimum and causes the transistor switch to turn off independently of said regulator circuit. Regulation of the output DC voltage is also maintained as a function of the present value of DC source voltage.