Fuji Electric Co., Ltd.

Fuji Electric Device Technology Co., Ltd.

Fuji Electric Technology Co., Ltd.

Jun Yabuzaki

Jian Chen

Takeshi Yokoyama

Yuta Endo

Tomonori Seki

An integrated circuit for a power supply circuit that generates an output voltage from an input voltage. The power supply circuit includes a transformer, a transistor controlling an inductor current flowing through a primary coil of the transformer, a first capacitor, and a first diode charging the first capacitor. The integrated circuit is configured to control switching of the transistor. The integrated circuit includes a first terminal configured to receive a voltage across the first capacitor; a second terminal configured to receive a feedback voltage corresponding to the output voltage; a driving signal output circuit configured to output a driving signal to increase a switching period of the transistor, in response to a decrease in a load current; a driver circuit configured to drive the transistor in response to the driving signal; and a determination circuit configured to determine whether the power supply voltage drops below a first voltage.

Integrated circuit and power supply circuit

An integrated circuit for a power supply circuit including a transformer having a primary coil, a secondary coil, and an auxiliary coil, and a transistor configured to control a current flowing through the primary coil. The integrated circuit includes a first terminal receiving a power supply voltage corresponding to a voltage from the auxiliary coil; a second terminal receiving a feedback voltage corresponding to an output voltage; a third terminal receiving a voltage corresponding to a current flowing through the transistor when the transistor is on; a determination circuit determining whether a detection circuit configured to detect a voltage generated in the auxiliary coil is coupled between the third terminal and the auxiliary coil; and a switching control circuit controlling switching of the transistor based on the voltages at the second and third terminals and a determination result of the first determination circuit.

Integrated circuit having switching control and power supply circuit including the same

An integrated circuit for a power supply circuit that includes a transformer including a primary coil, a secondary coil, and an auxiliary coil, and a transistor controlling a current flowing through the primary coil. The integrated circuit includes a first determination circuit determining a state of the load; a second determination circuit determining whether a current of the secondary coil is in a continuous mode and a discontinuous mode, in which the current of the secondary coil respectively does not reach, and reaches, zero when the transistor is off; an oscillator circuit outputting an oscillator signal; and a switching control circuit controlling switching of the transistor in response to a determination result of the second determination circuit and the oscillator signal, and in response to the oscillator signal irrespective of the determination result of the second determination circuit, respectively when the state of the load is light and heavy.

Integrated circuit for load-state-based control and power supply circuit containing the same

A dimmer, according to an embodiment, includes a reference voltage circuit configured to output a reference voltage at a constant voltage when a power source voltage is higher than or equal to a predetermined threshold value, and output the reference voltage at a voltage proportional to the power source voltage when the power source voltage is lower than the predetermined threshold value. The dimmer further includes a bias current circuit; a control current circuit; an analog-to-digital converter; an output signal generation circuit; a first constant-current source; and a switch connected to the first constant-current source.

Dimmer and power converter

A signal converter circuit includes a frequency detection circuit configured to determine whether an external control signal is a PWM signal. A PWM frequency converter circuit is configured to detect, when a PWM signal is input, a duty cycle of the PWM signal and to generate a first digital signal. An AD converter is configured to generate a second digital signal based on an input DC voltage or a voltage attributable to a variable resistor to digital data using a maximum AD convertible input voltage as a duty cycle of 100%. An output signal generation circuit is configured to generate, based on the first or second digital signals output from the PWM frequency converter circuit or the AD converter, a PWM signal with a duty cycle based on that first or second digital signals.

Power converter

A switching power supply device having a synchronous rectifier IC on a secondary side, responds to an anomaly on a primary side based on detecting an occurrence of the anomaly on the secondary side. When a secondary side synchronous rectifier IC detects an anomaly, a current is output from the anomaly-time current output terminal of the secondary side synchronous rectifier IC. By the output current flowing through a resistance, a voltage at an output voltage detection point is raised to increase a current through the cathode of a shunt regulator. In so doing, a current flowing through a photodiode of a photocoupler also increases, and the FB terminal voltage of a switching control IC connected to a primary side phototransistor decreases. The primary side switching control IC operates to minimize output power, reduces a secondary side output voltage, or stops an operation of the switching power supply device.

Switching power supply device

An overcurrent protection control circuit detects a low set value of an output voltage from a drop in voltage at a VCC terminal below a reference voltage. The overcurrent protection control circuit switches an overcurrent limit value from a high reference voltage to a low reference voltage and switches a maximum limit value of a switching frequency from a high first maximum switching frequency to a low second maximum switching frequency. By doing so, an overcurrent limit value of a switching element and a maximum limit value of a switching frequency are set to low values and a rise in output current is suppressed.

Switching power supply apparatus

The invention provides a switching power supply device such that the occurrence of noise is reduced by jitter control of a switching frequency. The switching power supply device includes a switching power supply device main body wherein a predetermined output direct current voltage is obtained by switching an input alternating current voltage using a switching element, a switching control unit that controls the switching frequency in accordance with a feedback voltage that indicates the difference between an output set voltage and the output direct current voltage, a jitter control unit that applies jitter to the switching frequency, and a jitter amplitude control unit that changes jitter amplitude caused by the jitter control unit in accordance with the feedback voltage.

In some aspects of the invention, overcurrent protection is carried out by suppressing fluctuations in current flowing through a switching element after overcurrent detection. A peak current reaching time detection circuit detects a peak current reaching time needed until current flowing through a switching element reaches a peak value. A difference voltage detection circuit, including a &#xbd; time detection circuit which detects a time of &#xbd; an ON time of the preceding cycle of the switching element, detects difference voltage between reference voltage used when detecting overcurrent flowing to a load and a signal which has detected current flowing through the switching element for the &#xbd; time. A delay time adjustment circuit, based on at least one of the peak current reaching time and difference voltage, carries out adjustment and control of a delay time occurring until the time when the switching element is turned off after detecting the overcurrent.

Power supply device control circuit

A multiplier multiplies a current signal of an Iy generator and a voltage signal from a Vx generator corresponding to a divided voltage value of an output voltage of a full-wave rectifier. The result of the multiplication is output as a current reference signal to the non-inversion input terminal of a current error amplifier. A current peak waveform generator circuit generates an envelope waveform of peak values of an inductor current. An Iz generator, when the envelope waveform exceeds a first threshold value smaller than a third threshold value set in an overcurrent protection circuit, curbs the inductor current by adjusting the size of a current signal output to the multiplier, and reducing the current reference signal.

Power factor correction type switching power supply unit

A soft-stop overvoltage protection circuit, into which a soft-stop overvoltage detection voltage proportional to a direct current output voltage is input, reduces the output of a multiplier in accordance with the soft-stop overvoltage detection voltage when the soft-stop overvoltage detection voltage exceeds a first threshold value. An overvoltage protection circuit, a second threshold value higher than the first threshold value being set, compulsorily turns off a switching element by outputting an overvoltage detection signal when the soft-stop overvoltage detection voltage exceeds the second threshold value. The soft-stop overvoltage protection circuit compulsorily increases the output of a voltage error amplifier circuit on the output voltage decreasing. When the output of the voltage error amplifier circuit increases suddenly, and the output voltage rises excessively, the soft-stop overvoltage protection circuit decreases the output of the multiplier, thus curbing the rise of the output voltage.

Soft-stop overvoltage protection circuit for power factor correction type switching power supply unit

A power factor correction type switching power supply unit can change reference values of an overcurrent limit at an optimum timing at a time of an overcurrent protection of a step-up type converter, so that no sudden change occurs in an inductor current. A detection level selection circuit selects one of first and second threshold values with a selection signal, and outputs it as an overcurrent detection level to an overcurrent detection circuit. An input voltage monitoring circuit determines the selection signal in such a way that the larger of two threshold values is selected when an alternating current input voltage exceeds a first reference voltage, and the smaller threshold value is selected when the alternating current input voltage does not exceed a second reference voltage, and outputs the selection signal to the detection level selection circuit at a timing at which the alternating current input voltage approaches a zero.

The electrode of a thin-type capacitor is connected to the rear surface of a p-type semiconductor substrate which is brought to a ground potential, by a conductive DAF (Die Attach Film) or by a conductive adhesive, and the electrodes of the front surface of the p-type semiconductor substrate are respectively connected with and stacked on the terminals of a thin-type inductor by bumps, whereby manufacturing costs can be reduced while the occurrence of noise can be suppressed and packaging area can be made small.

Composite semiconductor device

In a switching regulator, an inductor L(in FIG.) and an output capacitor Care connected on the output side of a series circuit consisting of a switching element (MOS transistor P) and a synchronous rectification element (MOS transistor N), and an N-channel MOS transistor Qis connected between an intermediate point of the inductor Land one terminal thereof. In addition, the frequency of oscillatorand the turning ON/OFF of MOS transistor Qare controlled by control unit. When output voltage Vout is to be altered, the switching frequency of MOS transistors Pand Nis increased, and the inductance of inductor Lis reduced, whereby a fast output change is permitted. On the other hand, during ordinary constant output voltage operation, the switching frequency is reduced, and the inductance value is increased, whereby high efficiency is attained.

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Matsumoto, Japan

Jun Yabuzaki