Panasonic Corporation

Matsushita Electric Industrial Co., Ltd.

Mikio Motomori

Takuya Ishii

Takashi Ryu

Hirohisa Tanabe

Tomoya Shigemi

Makoto Ishimaru

Kazuhito Kimura

Hiroki Akashi

Satoshi Wada

Tamotsu Yamamoto

Masato Yoshida

Junichi Morita

Richard Oswald

Masayasu Ito

Takanori Namba

Satoshi Kikuchi

Yoshihisa Minami

Daijiro Arisawa

Masaaki Koto

Jun-ichiro Hara

Katsuyuki Tabata

Yoichi Deguchi

Rumi Nakai

A semiconductor light source lighting circuit includes a voltage step-down unit configured to generate a drive voltage lower than an input voltage by turning on or off a first switching element in a voltage step-down mode, a voltage step-up unit configured to generate the drive voltage higher than the input voltage by turning on or off a second switching element in a voltage step-up mode, and a controller. The controller includes a charge pump unit configured to repeat charging from the drive voltage to a second capacitor and discharging from the charged second capacitor to the first capacitor in the voltage step-up mode, and a switch drive unit configured to apply a voltage higher than the voltage at the other end of the first switching element to the control terminal of the first switching element by using a voltage of the charged first capacitor.

Semiconductor light source lighting circuit and vehicular lamp

A current limiting circuit for a boost converter includes a voltage divider circuit between a main switch which flows a current to an inductor and a comparator included in a current detecting circuit. The voltage divider circuit includes two transistors of the same type as that of the main switch, which are connected in series. One of the two transistors is a sub-switch which is connected between a voltage division point and a drain terminal of the main switch, and is turned on/off in synchronization with the main switch in accordance with an output signal of a control circuit. The other transistor is a detection resistance transistor which is connected between the voltage division point and a source terminal of the main switch, and whose gate terminal is connected to a bias voltage so that the detection resistance transistor is always on.

Current limiting circuit

To securely detect the short-circuited state of a rectifier without detecting current and to protect a switching device in a DC-DC converter, in a state in which the potential at the connection point of the rectifier and the switching device is detected and a drive signal turns ON the switching device, the protection circuit of the DC-DC converter is configured to securely turn OFF the switching device when the potential at the connection point is a predetermined potential or more.

DC-DC converter

A power supply device includes an inductor controlled by switching to be charged or discharged such that a DC input voltage is boosted and a capacitor which smoothes the boosted voltage to generate a DC output voltage. Specifically, the power supply device further includes a transistor connected between the inductor and the capacitor to carry out a rectification function; an output voltage determination circuit which refers to the DC input voltage and the DC output voltage to determine the level of these voltages; and a current control circuit which controls a current flowing through the transistor such that the current has a predetermined value when the output voltage determination circuit determines that the DC output voltage is lower than the DC input voltage.

Power supply device

The present invention provides a current-mode control step-up converter capable of reducing the minimum duty ratio to a sufficiently small value and facilitating the setting of the maximum duty ratio. The step-up converter comprises a current detectorfor generating a current detection signal Vc corresponding to the current of a rectifier; an error amplifierfor generating an error signal Ve corresponding to an output DC voltage Vo; and a control circuitfor turning ON/OFF the main switchon the basis of the current detection signal Vc and the error signal Ve. The control circuitcomprises a comparatorand a timer circuit. With this configuration, the ON time of the main switchis set at a predetermined value, and the valley value of an inductor current changing in a triangular waveform is controlled. Hence, the OFF time of the main switch is adjusted to stabilize the output. Since the ON time of the main switchcan be set as desired, the minimum duty ratio can be reduced to zero or a sufficiently small value.

Step-up converter

The present invention provides an efficient multi-output power supply apparatus that enables a reduction in the on voltage of a main switch in a step-down power supply circuit or the like over a wide input range from a low input to a high input. The power supply apparatus includes a first power supply circuit that increases an input voltage from an input power source to output a first output voltage Vo, and a second power supply circuit that outputs a second output voltage Voobtained from the input voltage via a main switch circuit connected to the input power source. The main switch circuit having a first switch element that is a PMOS transistor and a second switch element that is an NMOS transistor connected to each other in parallel. The first output voltage Vois applied to a gate of the second switch element.

Multi-output power supply apparatus

A step-up power supply device includes: a step-up converter; a startup circuit which controls the on/off operation of a switch element of the step-up converter when an output voltage of the device is smaller than a reference voltage; and a control circuit which operates in substitution for the startup circuit when the output voltage is higher than the reference voltage to control the on/off operation of the switch element such that the output voltage reaches a target value. The startup circuit includes an oscillation circuit for generating a pulse signal which has a predetermined on/off ratio, a current comparison circuit for comparing a current of the switch element with a predetermined restriction value, and a drive circuit for generating a drive signal based on which the switch element is turned on/off, the drive signal being generated from the pulse signal to turn on the switch element, and the drive signal being generated from the output of the current comparison circuit or the pulse signal to turn off the switch element.

Step-up power supply device

A drive circuit drives a switch element having a first terminal, a second terminal, and a control terminal. A direct-current voltage is applied to the first terminal. The drive circuit includes a capacitor which is charged when the switch element is in the OFF state, and applies a charged voltage between the control terminal and the first terminal of the switch element or between the control terminal and the second terminal of the switch element when the switch element is in the ON state.

Drive circuit and switching regulator comprising the same

A step-up converter includes an inductor which receives input voltage Vi at one end, a first FET of the first conduction type which functions as a switch for determining whether or not energy is accumulated in the inductor, a second FET of the second conduction type which rectifies a current output from the other end of the inductor, an output capacitor having an end connected to the source of the second FET, a current detection circuit, and a feedback control circuit. The current detection circuit detects a current flowing through the first N-channel FET to output current detection signal Vc. The feedback control circuit controls the operations of the first N-channel FET and a P-channel FET based on current detection signal Vc.

A current detection circuit of the present invention has a switching devicean auxiliary switching devicean offset voltage source comprising an offset resistor deviceand a current source circuita compensation circuit, comprising a differential amplifierand a compensation transistorfor adjusting the output current of the auxiliary switching deviceso that the potential obtained by subtracting the voltage drop across the offset resistor devicefrom the output potential of the switching deviceis equal to the output potential of the auxiliary switching devicebeing configured that the detection level of the current flowing in the switching deviceis shifted by an offset amount.

Current detection circuit and switching power supply

In a DC-DC converter conforming to the current mode control system, in which the valley value of an inductor current is controlled for output control, a current detection circuitis configured to detect the current flowing from a low-side FETto an inductorusing an FET, an NPN transistor, an NPN transistor, a PNP transistor, a PNP transistorand a resistor, to detect the current flowing from the inductorto the low-side FETusing an FET, a differential amplifier, an FETand the resistor, and to output a current detection signal Vc.

The switching regulator comprises a main switch, a rectifier switch, an RS-flipflop, a judging unit, an edge pulse generator, a second prohibiting unit, and a reference voltage source. When a voltage drop caused due to an on-resistance of the main switch exceeds a predetermined value, the judging unit sets a set signal of the RS-flipflop at a high level, and thereby an overcurrent is cut off. The edge pulse generator monitors a gate voltage of the rectifier switch, and sets a prohibition signal at a high level for a predetermined time period from the trailing edge. Then, the second prohibiting unit sets the set signal at a low level, and prohibits cutting the overcurrent off. Herewith, the likelihood that the main switch will be destroyed by the overcurrent can be reduced.

Overcurrent protection device

A current detection circuit of the present invention has a switching device; an auxiliary switching device; an offset voltage source comprising an offset resistor deviceand a current source circuit; a compensation circuit, comprising a differential amplifierand a compensation transistor, for adjusting the output current of the auxiliary switching deviceso that the potential obtained by subtracting the voltage drop across the offset resistor devicefrom the output potential of the switching deviceis equal to the output potential of the auxiliary switching device, being configured that the detection level of the current flowing in the switching deviceis shifted by an offset amount.

Current detection circuit and switching power supply using the same

An output detection feedback section () for controlling the power supply output voltage of a converter unit () in response to an error signal Ve has an error amplifier () for outputting the error signal Ve, a phase compensation circuit (), a state detection circuit (), and a response compensation circuit () for setting the voltage of a capacitor () of the phase compensation circuit () to a predetermined value. When output voltage is switched, the output voltage is fixed at the predetermined value in a DC manner while a transitional response of the error signal (Ve) is accelerated, so that the output voltage is changed at a high speed to a desired value and the overshoot and undershoot are suppressed around the desired value.

Power supply

A method of regulating an output voltage by utilizing a switching regulator, where the switching regulator includes a high side switch, a low side switch having an active diode, a controller coupled to the high side switch and the low side switch, and a current measuring circuit coupled to the high side switch. The method includes the steps of: measuring the output voltage and if the output voltage is below a desired level, activating the high side switch so as to provide current to a load capacitor via a load inductor, if the voltage is above the desired level, activating the low side switch so as to sink current from the load capacitor via the load inductor; and utilizing the current measuring circuit to measure the current flowing through the high side switch in either a positive direction or a negative direction, where the controller is operable for controlling the current measuring circuit and disabling active components contained in the current measuring circuit and the active diode when the active components are not utilized during operation of the switching regulator so as to reduce operational power requirements of the switching regulator.

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Osaka, Japan

Mikio Motomori