Ricoh Company, Ltd.

Ricoh Electronic Devices Co., Ltd.

Yohichi Shiwaya

Toshiki Kishioka

Shinya Shimizu

Koichi Hagino

A step up/down switching regulator converts an input voltage of an input terminal into a predetermined setting voltage in a step up/down manner and outputs the setting voltage as an output voltage from an output terminal. The step up/down switching regulator includes a bypass mode in which the input voltage is directly bypassed to the output terminal without performing a step up/down switching, and a step up/down switching mode in which the step up/down switching is performed. The step up/down switching regulator includes a step up/down output unit, a step up/down control unit, and a mode select terminal.

Step up/down switching regulator

A switching regulator including an output switch element; a rectification switch element; an oscillation circuit; an error amplifier circuit; a slope circuit; a first voltage comparison circuit; a second voltage comparison circuit; a one pulse generation circuit; a control circuit; and a backflow detection circuit, and a control method thereof suppress variations to be stabilized with respect to a target value of the load current for switching between a PWM control and a PFM control, and ensure the switching from the PFM control to the PWM control or from the PWM control to the PFM control even if various parameters including external elements such as chips, coils, and capacitors vary.

Switching regulator and control method thereof

A switching power supply unit of a non-insulated, synchronous rectification type converts a voltage input to an input terminal into a predetermined voltage and outputs the voltage. The unit includes an inductor, a plurality of output switching elements, a plurality of rectifying switching elements, a switching element control circuit, a switching regulator integrated circuit, and a plurality of buffer circuits. The output switching elements, the rectifying switching elements, the switching element control circuit and the buffer circuits are integrated on the switching regulator integrated circuit.

Switching power supply unit

A disclosed operation control method of a charge pump circuit for boosting an input voltage to a desired magnitude in the range between the input voltage and twice the input voltage and outputting the boosted voltage. The method includes the steps of (a) during a charging period, charging, with the input voltage, one or more of the capacitors connected in series by selectively turning on one or more of the first switches in accordance with the desired voltage magnitude, turning on the third switch, and selectively turning on the second switch or one of the fourth switches; and (b) during a discharging period, turning off the third switch and the second switch or the fourth switch having been turned on; selectively turning on one or more of the first switches; and turning on one or more fourth and the fifth switches.

Operation control method of charge pump circuit

A power supply circuit includes a charge pump circuit configured to raise a voltage inputted from an input terminal and supply the raised voltage from an output terminal to a given load and a control circuit unit. The charge pump circuit includes a fly-back capacitor configured to store a charge of the voltage inputted from the input terminal and an output transistor connected between one terminal of the fly-back capacitor and the output terminal of the charge pump circuit. The control circuit unit receives a reference voltage and the voltage outputted from the charge pump circuit and is configured to generate a proportional voltage proportional to the voltage outputted from the charge pump circuit and output a voltage to control the output transistor depending on a difference between the proportional voltage and the reference voltage so that the proportional voltage has the same voltage level as the reference voltage.

Power supply circuit and method for controlling the same

A load driving circuit is disclosed that allows a charge pump circuit to operate at an optimum step-up ratio without frequently changing the step-up ratio. The load driving circuit includes a step-up circuit; a current setting circuit that sets a value of an electric current to be supplied to a load; a constant current circuit generating a constant electric current having the set value; a determination circuit; and a control circuit. In response to a load current setting signal, the current setting circuit sets the electric current to be maximum, and decreases the electric current step by step down to a preset value. Each time the electric current is decreased by one step, the control circuit changes the step-up ratio according to the determination results of the determination circuit, until the constant current circuit supplies the set electric current.

Load driving circuit and method of setting load current thereof

A power supply device includes a step-up circuit configured to supply a driving voltage to a load, a comparison circuit configured to compare an output voltage from the load with a reference voltage, and a control circuit configured to control the step-up circuit based on a comparison result generated by the comparison circuit. The step-up circuit includes multiple operation modes each outputting a given voltage not lower than a power source voltage. The control circuit controls the step-up circuit to operate in one of the multiple operation modes. The control circuit maintains a current operation mode of the step-up circuit until the output voltage from the load decrease to below the reference voltage and, when the output voltage from the load is less than the reference voltage, switches the operation mode to another operation mode to output a voltage higher than a voltage output in the current operation mode.

Growing community of inventors

Osaka, Japan

Yohichi Shiwaya