The present invention relates to a DC-DC converter, and aims at preventing a flywheel switch from being destroyed. A PWM control circuit outputs an oscillation signal in order to alternately switch between a main switch and a rectification switch, and a flywheel switch. A state detecting unit generates a control instruction signal for a controlling unit, if the DC-DC converter is powered down or if it is overloaded. The controlling unit turns off the flywheel switch by controlling a driving circ...

A power converter nearly losslessly delivers energy and recovers energy from capacitors associated with controlled rectifiers in a secondary winding circuit, each controlled rectifier having a parallel uncontrolled rectifier. First and second primary switches in series with first and second primary windings, respectively, are turned on for a fixed duty cycle, each for approximately one half of the switching cycle. Switched transition times are short relative to the on-state and off-state times o...

A switching power supply unit includes: a switch circuit equipped with a first transistor, the switch circuit converting a DC input into an AC; a transformer for transforming the AC; an output rectifier equipped with a second transistor serially connected to the transformer and a third transistor connected in parallel to the transformer, the output rectifier rectifying the output of the transformer; and a control circuit for controlling ON/OFF of the first to third transistors. The control circu...

There is provided a synchronous rectifier circuit that makes it possible to secure sufficient driving voltage for the rectifier switch regardless of the voltage of the secondary winding. In this synchronous rectifier circuit, the primary winding is insulated from the secondary winding and a rectifier switch is provided on the secondary side. An auxiliary switch, a diode, and an auxiliary winding are also provided on the secondary side. The emitter of the auxiliary switch and the cathode of the d...

A forward converter circuit that includes synchronous rectifiers as the forward and freewheeling rectifying elements in the output stage. The forward converter also includes a drive circuit for the synchronous rectifiers. The drive circuit includes an auxiliary secondary winding on the power transformer which is used to generate the gate control signal for the forward synchronous rectifier and an auxiliary winding on the output inductor which is used to generate the gate control signal for the f...

The present invention discloses a self-excitation synchronous rectification driver, which comprises a self-excitation coil, a self-excitation driver, a synchronous-signal source, a pulse transformer, a positive/negative edge detector, and a latch unit. The synchronous-signal source generates a synchronous signal to attain an external synchronous function. When the frequency is abnormal, the first and second rectifier switches of the rectification unit of the power supply are forced to turn on or...

Phase compensation of a voltage appearing on physical terminals of a synchronous rectifier switching element such as a MOSFET is used to substantially eliminate effects of package inductance of the synchronous rectifier and thus approximate the actual voltage across the circuit element providing synchronous rectification in, for example, a switching power converter. By doing so and using the phase compensated signal to control the synchronous rectifier, switching time may be more suitably contro...

A power converter nearly losslessly delivers energy and recovers energy from capacitors associated with controlled rectifiers in a secondary winding circuit, each controlled rectifier having a parallel uncontrolled rectifier. First and second primary switches in series with first and second primary windings, respectively, are turned on for a fixed duty cycle, each for approximately one half of the switching cycle. Switched transition times are short relative to the on-state and off-state times o...

A power converter nearly losslessly delivers energy and recovers energy from capacitors associated with controlled rectifiers in a secondary winding circuit, each controlled rectifier having a parallel uncontrolled rectifier. First and second primary switches in series with first and second primary windings, respectively, are turned on for a fixed duty cycle, each for approximately one half of the switching cycle. Switched transition times are short relative to the on-state and off-state times o...

A DC-DC power converter is presented. According to one embodiment, the converter includes first and second transformers, and a double-ended input circuit, including first and second primary switches, for generating an alternating voltage across the primary windings of the first and second transformers. The converter also includes a control circuit (such as, for example, a PWM control circuit) for controlling the primary switches such that the primary switches are simultaneously OFF for a first t...