Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Minoru Fukui

Takashi Kunimatsu

Yoshiaki Hachiya

Ryutaro Arakawa

Ryutarou Arakawa

The LED driving semiconductor apparatus for driving at least one LED includes an input terminal, an output terminal, a switching element block and a controller. The input terminal is connected to a high voltage side of a rectifying circuit for rectifying an alternating current voltage, and inputs the voltage from the rectifying circuit. The output terminal is provided for supplying a current to the LED. The switching element block is connected between the input terminal and the output terminal, and has a first switching element. The controller includes a regulator for generating a power source voltage for driving and controlling the switching element block, and a drain current detector for detecting a drain current of the switching element block, and performs on/off control of the first switching element to block the drain current of the switching element block when the drain current reaches a predetermined threshold.

Led driving semiconductor apparatus provided with controller including regulator and drain current detector of switching element block

There is provided a light emitting diode drive apparatus which decreases a conducted emission. The light emitting diode drive apparatus includes a light emitting diode to which a voltage is applied from a voltage source, a choke coil connected in series to the light emitting diode, a rectifier diode connected in parallel to the light emitting diode and the choke coil to supply a back electromotive force generated in the choke coil to the light emitting diode, and a switching drive circuit including a switching element and a control circuit block. The switching element determines whether a current is applied or not applied to the light emitting diode. The control circuit block controls on/off timing of the switching element to control the current flowing into the light emitting diode. The choke coil is connected between the light emitting diode and the switching element.

Light emitting diode drive apparatus

A reference supply voltage circuit includes a detecting device for detecting a first reference voltage, a comparator, and a preventing circuit for preventing any false operation during pre-operation indefinite time interval. The comparator outputs a signal which controls an operation circuit whose supply voltage is a second reference voltage equal to or lower than the first reference voltage. The preventing circuit maintains the second reference voltage to a circuit reference potential when the first reference voltage is lower than a first predetermined voltage, sets the second reference voltage to a voltage equal to the first reference voltage when the first reference voltage is equal to or higher than the first predetermined voltage and lower than a second predetermined voltage, and sets the second reference voltage to a voltage proportional to the first reference voltage when the first reference voltage is equal to or higher than the second predetermined voltage.

Reference supply voltage circuit using more than two reference supply voltages

A switching control circuit is provided which can increase the off period of a switching element when the on period of the switching element is equal to the sum of the minimum pulse period (blanking period (a fixed period during which drain current is not detected after the switching element is turned on)) and a detection delay period (a period from when the drain current is equal to or higher than a detection criterion to when the switching element is actually turned off) and PWM control is disabled. An off period adjusting circuit generates, when the on period of the switching element is equal to the minimum pulse period, an adjusting signal OFF_C for increasing the off period of the switching element and supplies the signal to an on/off circuit for controlling the periodic on/off operation of the switching element.

Switching control circuit with off period adjustment

The peak current flowing to the switching device drops in a no-load state with PWM control, but because the number of switching operations is constant regardless of the load, further reducing power consumption is difficult. The switching power supply device has a PWM signal generator for generating a PWM signal, a switching device Qfor switching the first supply voltage VIN based on the PWM signal, converters for outputting the difference between a second supply voltage and a reference voltage as a difference signal, and an intermittent oscillation control circuit for stopping the switching operation of the first switching device when the difference signal is less than a predetermined first threshold value (Vp). The PWM signal generator changes the pulse width based on the difference signal to generate the PWM signal.

Switching power supply device

The semiconductor device of this invention includes a first die pad down-set away from boundary portions between inner lead portions and outer lead portions; a first semiconductor chip mounted on the first die pad; a chip-shaped electronic component with a small thickness mounted on a second die pad formed by increasing the width of at least one of the inner lead portions; metal wires; leads each having an inner lead portion and an outer lead portion; and an encapsulation resin part for encapsulating the die pads, the semiconductor chip, the chip-shaped electronic component, the inner lead portions and the metal wires.

Growing community of inventors

Osaka, Japan

Minoru Fukui