Matsushita Electric Industrial Co., Ltd.

Omron Corporation

Satoru Takahashi

Seiki Yamaguchi

Kouji Takada

Yoshihiro Mori

Yoshiaki Hachiya

Masaki Sugihara

Ryuma Hirano

Yuji Yamanishi

Yasuhiro Takebayashi

Yuji Ueno

Seiji Sogo

Yoshikazu Hirai

Yukiko Yonezawa

Schunkichi Sasaki

Overload protecting operation is performed by controlling the current peak value of a switching devicethrough the use of a comparator, a NAND circuit, and so on according to variations in feedback current being input to a feedback signal control circuit, internally setting the overcurrent protection of switching devicethrough the use of a clamp circuit, charging a capacitorwhen having fallen below a specified current smaller than current required for the overcurrent protection for a fixed time period, and detecting rise in voltage VOL at the capacitorto a constant voltage to stop switching operation. By achieving the overload protection under normal load and the overcurrent protection against peak load in a single switching power supply unit, problems such as the complexity of the unit and an increase in the element count of the control circuit are solved.

Switching power supply unit and semiconductor device for switching power supply

It is an object to control the peak of drain current and control overload in a same switching device in a switching power supply which has a load of a transformer and so on, and to prevent a complicated circuit and an increase in the number of terminals of a control circuit. Overload protection is performed as follows: according to a change in a feedback current which is an input to a feedback signal control circuit, the peak value of the current of a switching element, a switching operation is performed intermittently to reduce power consumption when the feedback current decreases at a light load, and an increase in the voltage of an FB terminal is detected and the switching operation is stopped in an overload state where overload protection is performed on the switching element.

Switching power supply

A switch driving portion includes a lever link mechanism which as a pair of lever members respectively rocking about a rocking fulcrum by interlocking with a push button portion when the push button portion is pushed and arranged so as to be faced each other and in which the both lever members are connected each other at their faced ends by joint members so that they can be folded and slid and a switch operating member for opening or closing a built-in switch when the lever link mechanism is rocked by pushing in the push button portion.

Push-button switch

In a semiconductor switch, a voltage detection circuit is provided so as to be in parallel with a first switching element for turning on/off a power supply to a load, in which a voltage detection portion for detecting a drain voltage of the first switching element by dividing a voltage upon a resistance ratio or the like and a second switching element are connected in series to each other. The second switching element is turned on/off in accordance with ON/OFF of the first switching element. Accordingly, detection of a drain voltage is performed normally when the first switching element is in an ON state. When the first switching element is in an OFF state, a leakage current can be reduced by the second switching element.

Semiconductor switch having a voltage detection function

A load driving device capable of preventing thermal destruction even when a load short-circuit or an overcurrent occurs, thereby having improved reliability, is provided. A load driving device, in which a power switch element for driving a load and a circuit for controlling the power switch element according to a signal V supplied from the outside are formed on one chip, is provided with an OFF-time delaying circuit for delaying an OFF-time transition of a level of an input signal at which the power switch element makes the transition from an ON state to an OFF state, according to a result of detection of a current flowing through the load and the level of the input signal to the power switch element.

Load driving device

The semiconductor device of the present invention includes: a semiconductor layer of a first conductivity type; source and drain regions of a second conductivity type, which are formed within the semiconductor layer; a channel region provided between the source and drain regions; and a gate electrode formed over the channel region. The device further includes: a buried region of the first conductivity type, at least part of the buried region being included in the drain region; and a heavily doped region of the second conductivity type. The heavily doped region is provided at least between a surface of the semiconductor layer and the buried region. The concentration of a dopant of the second conductivity type in the heavily doped region is higher than that of the dopant of the second conductivity type in the drain region.

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Kyoto, Japan

Satoru Takahashi