Rohm Co., Ltd.

Takatsugu Wachi

Yosuke Fukumoto

Masashi Nagasato

Akira Nakamura

Yoshio Higashida

Shidong Guan

Hiroto Oshita

Takehiro Yoshida

Yuki Iwata

George G Tan, Jr

A power supply semiconductor device includes: first and second external terminals connected to positive and negative electrodes of input capacitor via first and second external current paths, respectively; third and fourth external terminals connected to the positive and negative electrodes of the input capacitor via third and fourth external current paths, respectively; first and second transistors provided between the first and second external terminals; third and fourth transistors provided between the third external terminal and the fourth external terminal; switch terminal commonly connected to connection node between the first and second transistors and connection node between the third and fourth transistors; and drive control circuit performing switching control to alternately turn on and off a set of the first and third transistors and a set of the second and fourth transistors, thereby generating a switching voltage at the switch terminal based on voltage across the input capacitor.

Power supply semiconductor device and DC/DC converter

A switching power supply circuit includes: a switching circuit switching an input voltage; a first amplifier generating a first voltage; a first phase compensation circuit including a first capacitor and compensating for a phase of the first voltage; a second amplifier generating a second voltage; a second phase compensation circuit including a second capacitor and compensating for a phase of the second voltage; and a drive control circuit executing a switching operation according to the second voltage, wherein the switching power supply circuit operates in a first or second mode, the drive control circuit performs, in the first mode, the switching operation, and stops, in the second mode, the switching operation, and when returning from the second mode to the first mode, a specific voltage corresponding to an output voltage is supplied to the second capacitor and a predetermined voltage is supplied to the first capacitor.

Switching power supply circuit and switching power supply device

An output transistor is made to perform switching operation synchronous with a clock signal in a current mode based on an error voltage, which is commensurate with the difference between a feedback voltage commensurate with an output voltage and a reference voltage, and a slope voltage, which is commensurate with a current that passes through the output transistor. Based on the result of comparison of the error voltage with a skip threshold voltage, a skip signal is generated. When the skip signal turns to high level in response to a light load, the switching operation is stopped. Thereafter, when the skip signal turns back to low level, the output transistor is turned on asynchronously with the clock signal.

Circuit for a switching power supply

A DC/DC converter has: a soft-start circuit, a variable output current generator, a constant current source, an oscillator, a slope circuit, a PWM comparator, and a control circuit operable to turn ON and OFF first and second transistors alternately based on a pulse width modulation signal. Through the switching operation of the first and second transistors, an input voltage is converted into a output voltage.

DC/DC converter and switching power supply having overcurrent protection

The step-up DC/DC converter () of the present invention has a synchronous rectifier transistor (M); an output transistor (M); a first back-gate control transistor (M) connected between an external terminal (T) and a back gate of the synchronous rectifier transistor (M); a discharge transistor (M) connected between the external terminal (T) and a ground terminal; and a control unit (X) for controlling the on/off state of the components described above. The control unit (X) switches off the first back-gate control transistor (M) and switches on the discharge transistor (M) when stopping the switching operation of the output transistor (M) and the synchronous rectifier transistor (M).

Step-up switching power supply device with current-limiting transistor

A power supply device is provided with an output transistor for outputting a switch voltage having a rectangular waveform, based on an input signal by being switching-controlled by a pulse width modulation signal; a reference voltage generating circuit for generating a prescribed reference voltage; an error amplifier wherein a feedback voltage depending on the switch voltage and the reference voltage are inputted, an error voltage is generated by amplifying a difference between the voltages, and changes a gain of itself, in accordance with a current signal generated inside based on the feedback voltage and the reference voltage; an oscillator for generating an oscillation signal; and a comparator wherein the oscillation signal and the error voltages are inputted and the pulse width modulation signal is outputted by comparing the voltages.

Power supply device with gain changing error amplifier

A temperature sensor including two transistors having different emitter current densities and performing temperature detection based on the fact that the difference in voltage between base and emitter changes with temperature. The temperature sensor is provided with a feedback circuit for controlling respective collector voltages and emitter currents such that the collector voltages of both transistors vary according to similar temperature characteristics.

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Kyoto, Japan

Takatsugu Wachi