Sanken Electric Co., Ltd.

Yukinari Fukumoto

Hiroshi Usui

Kengo Kimura

Koichi Morita

Ryuichi Furukoshi

Syohei Osaka

Toshirou Takeuchi

Yasuhiro Rikiishi

Syouhei Osaka

A discharge-lamp lighting apparatus includes series circuits connected to each end of a DC power source, a transformer, FETs Qp, Qn, Qp, and Qn, and a drive circuit. The drive circuit includes transistors Qand Qto discharge gate-source capacitances of the Qpand Qp, resistance elements to determine gate potentials of the transistors Qand Qwhen the transistors Qand Qare turned on, transistors Qand Qto charge the gate-source capacitances of the Qpand Qp, constant current circuits, and switches connected in series with the series circuits of the constant current circuits and resistance elements, respectively, to turn on/off the constant current circuits.

Discharge-lamp lighting apparatus

A switching power source device of resonance type is provided which comprises an output voltage detectorfor detecting output voltage on a loadto produce a detection signal; and a control circuitfor applying on-off signals V, Vto each control terminal of first and second MOS-FETsin response to the detection signal from the output voltage detectorControl circuitcomprises a frequency control circuitfor controlling the on-off operation of first and second MOS-FETsin response to the level of detection signal from output voltage detectorto decide the switching frequency of first and second MOS-FETsFrequency control circuitis provided with an on-time control circuitwhich more reduces the on-span of one of first and second MOS-FETsduring the light load period in response to the level of detection signal from output voltage detectorthan during the non-light load period to control power consumption, reduce switching loss and noise, and improve switching efficiency in electronics.

Switching power source device of resonance type capable of controlling switching loss and noise

A synchronous commutation DC-DC converter comprises a current detection transformer () for detecting currents (I, I) flowing through the primary circuit, first and second DC bias power sources () generating bias voltages (V, V) larger than the voltage corresponding to the exciting current of a transformer (), and first and second comparators () for driving first and second commutation MOS-FETs () when the detection voltage (V) of a current detection resistor () exceeds the bias voltages (V, V) of the first and second DC bias power sources (). Since each commutation MOS-FET () in the secondary circuit is driven in synchronism with the currents (I, I) of the primary circuit from which the exciting current component of the transformer () is removed, it is possible to minimize switching loss of each commutation MOS-FET () in the secondary circuit and enhance conversion efficiency of the synchronous commutation DC-DC converter.

Synchronous commutation DC-DC converter

A DC power source device comprises a MOS-FETwhich performs the intermittent switching operation for converting DC input from a DC power supplyinto high frequency electric power; a control circuitfor turning MOS-FETon and off; and a rectifying smootherfor converting the high frequency electric power through MOS-FETinto a DC power output supplied to a loadControl circuit 9 comprises an output current controllerfor controlling the on-off term of MOS-FETto make DC output current Ithrough loadsettle toward a rated value I; a shunt regulatorfor receiving a drive current Isupplied from rectifying smootherand producing a reference voltage Vto regulate the rated value Iof output current controllerand a constant current sourcefor keeping drive current Ion a substantially constant level under the rated output current value condition and reduced output voltage condition. Constant current sourcefunctions to supply shunt regulatorwith minimum drive current Ito maintain reference voltage Von a constant level under the reduced output voltage, and also to control drive current Ito shunt regulatorto a necessary but minimum level under the rated value of DC output current.

DC power supply apparatus

A converter is provided in which the cost and size of which are reduced by a decrease in current consumption with no need of large elements or radiation fins. The converter has a switching element (Q) being connected to a DC power source through a primary winding (P) of a transformer (T), a control circuit () for turning on/off the switching element (Q), a diode (D) and a capacitor (C) for rectifying/smoothing the voltage induced in the secondary winding (S) of the transformer (T) to extract DC output, and a starting circuit () for starting the control circuit (). The starting circuit () operates as a constant current circuit (Q, R, R, ZD, D) while starting the control circuit (), and as a constant voltage circuit (Q, R, R, ZD, D) after starting the control circuits ().

Converter with start-up circuit

A transformer has a primary winding connected to a pair of DC input terminals via an active switch, and a secondary winding connected to a pair of DC output terminals via a first rectifying and smoothing circuit. The active switch is driven constantly under normal load, and at intervals under light load, under the direction of a switch control circuit. This switch control circuit is powered with a control voltage fed from a second rectifying and smoothing circuit which is connected to a tertiary winding of the transformer. In order to preclude malfunctioning or nonoperation in the event of an abnormal drop of the control voltage during operation in light load mode, the switch control circuit is equipped to drive the active switch at shorter intervals in control voltage recovery mode when the control voltage falls below a predefined limit than the normal intervals of the light load mode.

Dual-mode switching DC-to-DC converter

A boost quantity detecting section () detects a boost quantity of an inductor (L). An operational amplifier () of a control section () compares the boost quantity detected by the boost quantity detecting section () with a reference voltage (ES). When a supply voltage supplied from an AC power source () reduces and an output voltage is unchanged, the boost quantity detected by the boost quantity detecting section () increases. When a signal level of a boost quantity detection signal is higher than the reference voltage (ES), a control section () reduces a target level of a switching current. The target level of the switching current decreases, so that the output voltage decreases and energy loss due to boosting reduces.

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Niiza, Japan

Yukinari Fukumoto