Zero-voltage switched FM-PWM converter

DETAILED DESCRIPTION A variable-frequency pulse-width-modulated boost converter is provided which allows for operation at very high frequencies with minimal transient turn-on losses.
A frequency control scheme is utilized where the controller for the converter causes switching to occur when the voltage at the drain of the MOSFET is near zero volts.
In addition to reducing transient turn-on losses, zero-voltage switching reduces noise generation in the circuit and simplifies the gate drive requirements.
Other optimal characteristics for D-C to D-C converters are met in addition to turning the switch on under a zero drain-to-source potential.
Maximum peak voltage across the switch is limited to the output voltage level.
In addition, peak and average currents through the switch are proportional to output power requirements.
According to a first embodiment of the invention, a D-C to D-C converter circuit comprises a first inductive means coupled to receive input power from an input line.
A switching means is coupled to the first inductive means for controlling the transfer of power from the first inductive means to an output line.
A current sensing means is coupled to the first inductive means for providing an output signal indicative of the voltage across the first inductive means to reset (trigger) a controller circuit which controls the switching means.
According to a second embodiment of the invention, a D-C to D-C converter circuit comprises a first inductive means coupled to receive input power from an input line.
A switching means is coupled to the first inductive means for controlling the transfer of power from the first inductive means to an output line.
A voltage sensing means is coupled to the switching means for providing an output signal indicative of the voltage across the switching means to reset a controller circuit which controls the switching means.
According to a third embodiment of the invention, a D-C to D-C converter circuit comprises a transformer having a primary winding and a secondary winding, the primary winding coupled to receive input power from an input line and the secondary winding coupled to the output line