Enhancement of the power conversion efficiency and reduction of switching noise of a power supply circuit are achieved. The power supply circuit includes, on the primary side, a composite resonance type converter formed from a current resonance type converter and a partial voltage resonance circuit in combination, and is configured so as to produce a plurality of secondary side DC output voltages. A particular one of the plural secondary side DC output voltages is controlled to a constant voltag...

An AC power source apparatus to be used in an AC corona generator necessary for a de-electrification/separation process, which is one of electrographic image forming processes, or in a case where a low frequency AC power source is required, has a construction such that a high-frequency pulse, whose time ratio is modulated trapezoidally with time, is applied to switching elements connected in inverse-series across a primary winding of a transformer, an inductance element having a regenerative dio...

A push-pull converter for converting an input voltage to a selectable output voltage is disclosed. The push-pull converter includes a pair of primary switches and a pair of primary windings of a transformer. The voltage stress across the primary switches is regulated by means of a clamp capacitor. The clamp capacitor clamps the voltage of the primary switches during the reset of the primary windings of the transformer. An alternate embodiment is also disclosed in which the voltage stress across ...

A drive device for a push-pull stage includes a microcontroller in the form of a pulse-width modulator which, starting with a selected switching frequency, varies the pulse-duty ratio (modulation) of the pulse-width modulated output signal and which, with chronological delay, controls the push-pull stage. The push-pull stage has at least one upper and one lower power switch, and the microcontroller has three pulse-width modulation outputs. The actual pulse-width modulated output signal is delive...

A DC to DC switching regulator includes a first pulse width modulator (PWM) (26) and two switching transistors (48) and (50) that are coupled to a transformer (18) to generate an output signal that has pulse widths variable in response to the PWM (26). The output of the transformer (18) is rectified to provide a regulated DC output. A second PWM (78) is provided to convert the amplitude of the regulated DC output to a stream of pulses that are input to an isolation transformer (112) by a push-pu...

A switched mode converter is disclosed that includes both voltage mode and current mode control. The switched mode converter also includes mode logic for switching between a voltage mode and a current mode. The converter includes current sensing circuitry for sensing the switcher current on the primary side of the transformer and the load current on the secondary side as well as voltage sensing circuitry for sensing the converter output voltage. When the load current is less than a predetermined...

A DC-DC converter for converting DC power received from a high-voltage DC power supply to a well-regulated output voltage that is significantly lower than the received voltage. The converter includes a regulated voltage-reduction stage which receives high-voltage DC electrical power and supplies DC electrical power at a voltage which is lower than that received. The converter also includes a separately regulated electrically isolated stage, energized by electrical power received from the voltage...

A power converter (10) operating in all four voltage-current quadrants includes an input voltage source (14), an output current independent of an output voltage and a switching arrangement (12, 16, 18, and 20) enabling an output terminal (26) to be in common with an input terminal. The output voltage can be unconstrained by an input voltage from the input voltage source.

A switching regulated power supply, the output voltage of which is regulated according to a pulse width modulation method, is provided with a reference oscillator for generating first and second synchronizing signals, phases of which are complement each other, first and second time constant circuits, to which the first and second synchronizing signals are supplied respectively, each one of the circuits having a resister and a capacity device including a variable capacity diode, charge speed up d...

A current source circuit is contained in an output control IC and amplifies a feedback current produced by a photocoupler by 7 to 10 times. The current amplifier has an adequate current amplification factor and is composed of an IC. A capacitor connected to the oscillator is charged by a current amplified at the current amplifier and a period of the output of the oscillator is controlled by the charging current. A conductive period of the switching device connected to the oscillator through a dr...