Panasonic Corporation

Matsushita Electric Industrial Co., Ltd.

Makoto Ishimaru

Takuya Ishii

Hiroki Akashi

Takashi Ryu

Mikio Motomori

Hirohisa Tanabe

Tomoya Shigemi

Yoshiyuki Konishi

Kazuhito Kimura

Junichi Morita

Masaaki Koto

Satoshi Wada

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 is intended to provide a DC-DC converter, in which the relationship between the duty ratio of a drive signal and the output DC voltage is nonlinear, being characterized in that the relationship between an error signal and the output DC voltage is linear, and that the design of stabilizing the feedback system is facilitated. The DC-DC converter comprises an error-amplifier circuit for generating the error signal that is obtained by amplifying the error between the output and a target value, an oscillating circuit for generating a triangular wave signal having an amplitude corresponding to the error signal, and a comparison circuit for comparing the triangular wave signal with a reference signal having a predetermined value and for generating the drive signal to turn ON/OFF a switching device.

DC-DC converter and control circuit thereof

For downsizing a charge pump circuit which selects a voltage multiple ratio, converts its input voltage and outputs the converted voltage, the number of switching devices of the charge pump circuit is reduced. The control circuit of the charge pump circuit is configured to carry out switching control for multiple switching devices and charge/discharge at least a first capacitor and a second capacitor so as to have at least a 2Vi mode for alternately repeating a first state and a second state, and a 1.5Vi mode for alternately repeating a third state and a fourth state, thereby carrying out boosting depending on the detected input voltage.

Charge pump circuit

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.

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.

DC-DC converter

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 DC-DC converter has switching means which generates a continuous switching voltage having a specified period from an input voltage and outputs the generated switching voltage, output voltage generating means which receives the switching voltage at an inductor and generates an output voltage obtained by rectifying and smoothing a voltage generated in the inductor, lamp signal generating means which generates a lamp signal and outputs the generated lamp signal, and control means which performs an arithmetic operation using a current signal relative to a current flowing in the inductor, an error signal relative to the output voltage, and the lamp signal to generate a control signal for controlling the operation of the switching means and outputs the generated control signal to the switching means. The lamp signal generating means includes first signal generating means for generating a first output signal based on a frequency divided signal having first and second periods obtained by dividing the time of a clock signal having the specified period and second signal generating means for generating a second output signal having a phase 180 degrees different from the phase of the first output signal based on the frequency divided signal, generates the lamp signal which rises after being held at a constant value for a specified time period in each of the first and second periods, and outputs the generated lamp signal.

Growing community of inventors

Osaka, Japan

Makoto Ishimaru