Rohm Co., Ltd.

Satoru Nate

Yoshinori Sato

Isao Yamamoto

Natsuki Yamamoto

Hiroshi Hayashi

Akinobu Sawada

Yifei Tang

Yoichi Tamegai

Akihiro Ono

Yohei Akamatsu

Makoto Hirata

Shingo Matsumaru

Sachito Horiuchi

Shinji Takizawa

Yuta Shiroishi

Hiroaki Sawaoka

A zero-cross detection device includes: an input terminal configured to receive an input voltage via a diode from an application terminal for an alternating-current voltage relative to a reference potential; an input circuit including a resistor between the input terminal and a terminal at the reference potential; a period detection circuit configured to detect the length of the period of the alternating-current voltage based on the interval of the timings at which the input voltage exceeds a threshold voltage; a peak detection circuit configured to detect the peak timing at which the input voltage reaches a peak in each period of the alternating-current voltage; and a zero-cross timing detection circuit configured to detect the zero-cross timing of the alternating-current voltage based on the results of detection by the period detection circuit and the peak detection circuit.

Zero-cross detection device and load driving system

A zero-crossing detection circuit includes a logic unit and an input stop detection unit. The logic unit is configured to estimate a zero cross of an AC signal in accordance with at least one of a first monitoring target signal and a second monitoring target signal, respectively input through diodes from a first node and a second node between which the AC signal is applied, so as to generate a zero-crossing detection signal. The input stop detection unit is configured to compare the first monitoring target signal with the second monitoring target signal after giving an offset to one of them so as to generate an input stop detection signal. The logic unit is configured to fix a logic level of the zero-crossing detection signal in accordance with the input stop detection signal.

Zero-crossing detection circuit

A power control device includes a mode setter configured to effect a change from a normal mode to a low-power mode upon detecting a light load in a burst operation, and a minimum on-period setter configured to, in response to a change to the low-power mode, change the minimum on-period of the switching transistor from a first minimum on-period to a second minimum on-period longer than the first minimum on-period.

Power control device, DC-DC converter, and AC-DC converter

There is provided a power supply controller including: a monitor voltage generation part configured to generate a monitor voltage according to a primary voltage of a transformer that forms an insulated switching power supply; a sample/hold part configured to sample/hold the monitor voltage and output a feedback voltage; and a controller configured to turn on/off a primary current of the transformer by a fixed on-time method according to the feedback voltage, wherein the sample/hold part samples/holds the primary voltage at a plurality of different timings and outputs one of a plurality of hold values as the feedback voltage.

Power supply controller and insulated switching power supply

This power supply IC is a semiconductor integrated circuit device serving as a main part for controlling a switching power supply and is formed by integrating a feedback resistor and an output feedback control unit on a single semiconductor substrate, said feedback resistor generating a feedback voltage by dividing the output voltage of the switching power supply (or the induced voltage appearing across an auxiliary winding provided on the primary side of a transformer included in an insulation-type switching power supply), said output feedback control unit performing output feedback control of the switching power supply in accordance with the feedback voltage. The feedback resistor is a polysilicon resistor having a withstand voltage of 100 V or more. A high-voltage region having higher withstand voltage in the substrate thickness direction than the other region is formed in the semiconductor substrate, and the feedback resistor is formed on the high-voltage region.

Power IC including a feedback resistor, and a switching power supply and electronic appliance including the power IC

The present disclosure provides a power supply control device. The power supply control device includes a feedback voltage generator, an on-timing setting unit and an off-timing setting unit. The feedback voltage generator is configured to generate a feedback voltage by sampling a primary voltage of a transformer that forms an insulated switching power supply. The on-timing setting unit is configured to turn on a primary current of the transformer based on a comparison result between the feedback voltage and a slope-shaped reference voltage. The off-timing setting unit is configured to turn off the primary current after a predetermined on time has elapsed since the primary current was turned on. A sampling timing of the primary voltage is set based on an on timing of the primary current.

Power supply control device and insulated switching power supply

A control device of a power factor correction circuit disposed in a power supply device that generates a direct-current output voltage from an alternating-current voltage applied to a power supply terminal pair, the power factor correction circuit including an inductor that is disposed between a full-wave rectification circuit that generates a full-wave rectified voltage by carrying out full-wave rectification of the alternating-current voltage and an output interconnect line to which a smoothing capacitor is connected and to which the output voltage is applied, and is inserted between the full-wave rectification circuit and the output interconnect line, and a switching element for controlling an inductor current that flows in the inductor. The control device controls a state of the switching element based on a pulsating voltage obtained by rectifying a voltage between the power supply terminal pair and the full-wave rectification circuit and a feedback voltage according to the output voltage.

Control device of power factor correction circuit, power factor correction circuit, power supply device, and semiconductor device

A zero-crossing detection circuit includes a zero-crossing detection unit arranged to compare a first monitoring target signal and a second monitoring target signal respectively input through diodes from a first node and a second node between which an AC signal is applied, so as to generate a first comparison signal, and a logic unit arranged to estimate a zero cross of the AC signal from the first comparison signal so as to generate a zero-crossing detection signal. The zero-crossing detection circuit preferably includes a monitoring unit arranged to adjust the first monitoring target signal and the second monitoring target signal to be suitable for input to the zero-crossing detection unit. The logic unit preferably counts a period of the first comparison signal and estimates a zero cross of the AC signal using a count value thereof.

There is provided a semiconductor device that includes a switch terminal; a ground terminal; an output switch connected between the switch terminal and the ground terminal and configured to be switchable between a first on-resistance value and a second on-resistance value higher than the first on-resistance value; a detection circuit configured to detect a short-circuit abnormality of the switch terminal by monitoring a switch voltage that appears at the switch terminal in a predetermined detection period; and a controller configured to perform a pulse-drive of the output switch by setting the output switch to the second on-resistance value in the detection period, continuously perform the pulse-drive of the output switch by setting the output switch to the first on-resistance value if the short-circuit abnormality of the switch terminal is not detected, and forcibly stop the pulse-drive of the output switch if the short-circuit abnormality of the switch terminal is detected.

Semiconductor device and isolated switching power supply

There is provided an isolated DC/DC converter including a primary side control circuit disposed on the primary side and switching a switching element connected in series with a primary side winding of a power transformer; a secondary side control circuit disposed on the secondary side and generating a control signal including first control information and second control information on the basis of the secondary side voltage; and an insulated transmission circuit transmitting, in an insulated manner, each piece of control information included in the control signal to the primary side control circuit. The primary side control circuit controls a switching frequency of the switching element on the basis of the first control information indicating the frequency of the control signal, and controls a peak value of a primary side current on the basis of the second control information indicating the pulse width of the control signal.

Isolated DC/DC converter and AC/DC converter

A non-isolated buck converter generates an output voltage by stepping down an input voltage obtained by subjecting an alternating-current voltage to full-wave rectification and smoothing, by using a step-down circuit including a switching element, an inductor, and a freewheeling diode. The switching element is disposed between a first terminal and a second terminal. A semiconductor device in charge of switching control operates with a potential at the second terminal as a reference. A control circuit provided in the semiconductor device includes a protecting circuit capable of referring to an evaluation voltage corresponding to a voltage between the first terminal and the second terminal at a sampling timing at which a predetermined period of time has passed from turning off of the switching element, and performing a protecting operation that fixes the switching element to an off state on the basis of the evaluation voltage.

Semiconductor device for non-isolated buck converter, non-isolated buck converter, and power supply device

A semiconductor device disposed on a primary side of a system generating a secondary side voltage in an insulated form from a primary side voltage includes: a signal generation circuit configured to generate a voltage information signal for transmitting voltage information based on the primary side voltage to a secondary side of the system in the insulated form.

Semiconductor device and load control system

A drive circuit includes: a current capability switch configured to switch a current capability of driving an output transistor of a switching power supply according to whether a switch current flowing through the output transistor is in a continuous mode or in a discontinuous mode.

Drive circuit

A current limiter 200 (corresponding to an example of a current detection circuit) has a comparator 210 and a variable delay unit 220. The comparator 210 switches a comparison signal OCP from a low level to a high level when the current to be monitored, which flows through an output switch, reaches a predetermined threshold value (in the present figure, when a sense voltage Vcs reaches an overcurrent detection voltage Vocp). The variable delay unit 220 measures a first time Tfrom when the output switch turns on by SET=H until when the comparison signal OCP switches to the high level and delays the comparison signal OCP by a second time T(=K&#xb7;T) proportional to the square of the first time Tto generate an overcurrent detection signal Sc. The variable delay unit 220 includes a first timer 223 for measuring the first time Tand a second timer 224 for generating the overcurrent detection signal Sc by delaying the comparison signal OCP by the second time T

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Kyoto, Japan

Satoru Nate