Ricoh Company, Ltd.

Shoichi Nitta

Masahiro Matsuo

Minoru Sugiyama

Ritsuko Nomura

Tomonari Kato

An I/O cell includes a reference output circuit that has a reference output transistor, connected to an output terminal, and has a reference pre-buffer, the reference pre-buffer driving the reference output transistor according to an input signal of the input terminal; adjustment output circuits that have an adjustment output transistor, connected to the output terminal and connected in parallel with the reference output transistor, and have an adjustment pre-buffer, the adjustment pre-buffer driving the adjustment output transistor according to the input signal; and a gate voltage detection control circuit that monitors all of gate voltages applied to the output transistors included in the reference output circuit and the adjustment output circuit. The gate voltage detection control circuit generates a timing when all of the output transistors are turned OFF when switching the H/L level of the output current to the load according to the change of the input signal.

I/O cell

The power circuit includes a switching regulator part, a series regulator part and a control circuit part for controlling operation of the switching regulator and controlling the second predetermined voltage of the series regulator part.

Power circuit and method of rising output voltage of power circuit

A DC-DC converting apparatus including a step-up and step-down circuit stepping up/down an input voltage to generate an output voltage and a PWM control circuit. The PWM control circuit generates an error signal, first to third voltages, a first triangular wave signal varying between the first and second voltages, and a second triangular wave signal varying between the third voltage and a fourth voltage determined based on the first to third voltages. The PWM control circuit compares the error signal with the first and second triangular wave signals and causes the step-up and step-down circuit to step up/down the input voltage based on the comparison. The first to fourth voltages V1 to V4 satisfy V1&#x3c;V4&#x3c;V2&#x3c;V3 and V4=V3&#x2212;(V2&#x2212;V1). At least one of the first to third voltages is variably set to make a time in which voltage ranges of the first and second triangular wave signals overlap longer than a delay time caused by the comparison.

DC-DC converting method and apparatus

A DC-DC converting apparatus including a step-up and step-down circuit stepping up/down an input voltage to generate an output voltage and a PWM control circuit. The PWM control circuit generates an error signal, first to third voltages, a first triangular wave signal varying between the first and second voltages, and a second triangular wave signal varying between the third voltage and a fourth voltage determined based on the first to third voltages. The PWM control circuit compares the error signal with the first and second triangular wave signals and causes the step-up and step-down circuit to step up/down the input voltage based on the comparison. The first to fourth voltages Vto Vsatisfy VVVVand VV(VV). At least one of the first to third voltages is variably set to make a time in which voltage ranges of the first and second triangular wave signals overlap longer than a delay time caused by the comparison.

DC&#x2014;DC converting method and apparatus

A power supply apparatus includes an output voltage generator, a reference voltage generator, a voltage divider, and a voltage control circuit. An input voltage is supplied from a direct current power source. The output voltage generator generates a constant output voltage based on the input voltage. The reference voltage generator generates a reference voltage. The voltage divider divides the constant output voltage into a divided voltage in accordance with a voltage dividing ratio variable in response to an externally-input control signal. The voltage control circuit controls the output voltage generator to regulate the constant output voltage such that the divided voltage from the voltage divider is equalized to the reference voltage.

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Osaka, Japan

Shoichi Nitta