Sanyo Electric Co., Ltd.

Sanyo Semiconductor Co., Ltd.

Semiconductor Components Industries, LLC

Yasunari Noguchi

Hiroyasu Ishida

Eio Onodera

Keiji Kobayashi

Yoshio Fujimura

Channel regions continuous with transistor cells are disposed also below a gate pad electrode. The channel region below the gate pad electrode is fixed to a source potential. Thus, a predetermined reverse breakdown voltage between a drain and a source is secured without forming a p+ type impurity region below the entire lower surface of the gate pad electrode. Furthermore, a protection diode is formed in a conductive layer disposed at the outer periphery of an operation region.

Insulated-gate semiconductor device with protection diode

Insulated-gate semiconductor device and PN junction diodes

Channel regions continuous with transistor cells are disposed also below a gate pad electrode. The channel region below the gate pad electrode is fixed to a source potential. Thus, a predetermined reverse breakdown voltage between a drain and a source is secured without forming a p+ type impurity region below the entire lower surface of the gate pad electrode. Furthermore, a protection diode is formed in polysilicon with a stripe shape below the gate pad electrode.

Insulated-gate semiconductor device

Channel regions and gate electrodes are also disposed continuously with transistor cells below a gate pad electrode. The transistor cells are formed in a stripe pattern and allowed to contact a source electrode. In this way, the channel regions and the gate electrodes, which are positioned below the gate pad electrode, are kept at a predetermined potential. Thus, a predetermined drain-source reverse breakdown voltage can be secured without providing a p+ type impurity region on the entire surface below the gate pad electrode.

Insulated gate semiconductor device

A quasi resonant type switching power supplying unit includes an overcurrent limiting circuit and an oscillation level comparison circuit. The overcurrent limiting circuit (i.e., a level determining circuit and a reference voltage generating circuit) receives a reverse electromotive voltage generated from an auxiliary winding which is electromagnetically connected with a primary winding when a MOSFET is in an OFF state, and produces a reference voltage stepwise based on the reverse electromotive voltage. The oscillation level comparison circuit receives a feedback voltage corresponding to electric power supplied to a load, and produces a control signal that switches the MOSFET into an OFF state when the feedback voltage exceeds the reference voltage.

Quasi resonant type switching power supply apparatus with overcurrent limiting

A switching power supply unit, for switching a rectified voltage supplied to a pulse transformer to supply a specified load voltage to a load connected to the secondary winding of the pulse transformer, wherein at the time of normal operation, a rectified voltage is supplied via a first resistor to a power supply terminal of a control circuit, together with supply of a voltage generated at a drive winding of the pulse transformer to the power supply terminal via a diode, and at the time of standby operation, a standby signal from outside indicating that the switching power supply unit has been put into standby mode is received, and it is possible to completely cut-off supply of power to a control section of the switching power supply unit constituting a main power supply when in standby mode, by supplying a voltage that is lower than a power supply threshold voltage capable of operating a control circuit to the power supply terminal.

Switching power supply

A storing circuit for storing control data for a varactor diode, a frequency divided data generating circuit for generating frequency divided data to set the local oscillating frequency of a local oscillating circuit, a determining circuit for computing a receiving frequency from the frequency divided data and determining whether or not the receiving frequency is within a designated frequency range and an arithmetic circuit for executing computation in compliance with data indicating the receiving frequency and control data stored in the storing circuit are provided, and the capacitance of the variable capacitance element is controlled by analog-conversion of an output signal from the arithmetic circuit, thus tracking errors caused by variation in tuning elements are prevented and an RF tuning circuit control interval is reduced.

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Gunma, Japan

Yasunari Noguchi