Ricoh Company, Ltd.

Tomonari Katoh

Masahiro Matsuo

Katsuhiko Manabe

Minoru Sugiyama

Makoto Matsushima

Tadayoshi Ueda

Shohichi Nitta

Kohichi Hagino

A DC converter with a halt mode setting is disclosed for preventing the occurrence of over-current while alleviating the increase in the size of circuits, along with a method for setting up such a halt mode. The DC converter includes a semiconductor switch, a clock generator for outputting a clock signal to a gate of the semiconductor switch to be utilized for controlling an on/off time of the semiconductor switch such that a predetermined power is output from the generator, and a drive circuit for switching the semiconductor switch to the continuous-on state according to a halt mode setting requirement regardless of the clock signal, when the semiconductor switch, normally repeating on/off operations responsive to the clock signal, is in its off-state.

DC converter with halt mode setting means

A switching regulator including two switching elements and a control switching part. The two switching elements perform a switching operation according to a control signal to control an output voltage. One of the two switching elements is larger in ON-resistance and smaller in control electrode capacitance than the other. The control switching part performs PFM control over the one of the two switching elements to output a first predetermined voltage in a first operation mode, performs PWM control over the two switching elements to output a second predetermined voltage higher than the first predetermined voltage in a second operation mode, and switches the first operation mode to the second operation mode by performing the PFM control, changing the first predetermined voltage to the second predetermined voltage, and switching the PFM control to the PWM control after a first predetermined time elapses since start of increase in the output voltage.

Switching regulator and method for changing output voltages thereof

A switching regulator converts an input voltage to a predetermined voltage and outputs the predetermined voltage to a load through an output terminal. The switching regulator includes a first switching element, a second switching element, a control switching circuit part, and a smoothing circuit. When a first operating mode in which a PFM control is performed and a voltage from the output terminal becomes a first voltage is shifted to a second operating mode in which a PWM control is performed and the voltage from the output terminal becomes a second voltage larger than the first voltage, the control switching circuit part increases the voltage from the output terminal stepwise progressively from the first voltage to the second voltage while performing the PWM control.

Switching regulator and method for switching output voltage thereof

A DC power supply capable of obviating undue resetting and malfunction of CPU, immediately after starting the operation of a switching regulator, by inputting sleep signals input asynchronously during a switching cycle of the switching regulator. In the DC power supply adapted to apply a DC voltage to an output terminal by selectively switching between a first voltage from a switching regulator and a second voltage, the switching regulator includes a first switching element and a inductor serially connected between an input terminal for receiving an input voltage and an output terminal, and a second switching element for use in synchronous rectification between the first switching element and the ground, together with a first drive circuit for driving the first switching element, a second drive circuit for driving the second switching element, and a control circuit for controlling the first and second drive circuits. The control circuit is configured to control signals to the first and second drive circuits such that the second switching element is kept turned off until the first switching element is turned on when the operation of the switching regulator is initiated.

DC power supply and integrated circuit device

A DC-DC converter is disclosed that includes a constant voltage circuit outputting a first voltage, a charge pump circuit outputting a second voltage, a current detection circuit converting the output current of the constant voltage circuit into a third voltage and outputting the third voltage, a first detection circuit detecting the first voltage and outputting a first detection voltage proportional thereto, a first overcurrent protection circuit comparing the third voltage and the first detection voltage and reducing the output first voltage and current of the constant voltage circuit when the third voltage exceeds the first detection voltage, a second detection circuit detecting the second voltage and outputting a second detection voltage proportional thereto, and a second overcurrent protection circuit comparing the third voltage and the second detection voltage and reducing the output first voltage and current of the constant voltage circuit when the third voltage exceeds the second detection voltage.

DC-DC converter

A switching regulator includes a first switching element to perform a switching operation in accordance with a first control signal input thereto to control an output voltage based on an input voltage, a second switching element having a size smaller than the first switching element to perform a switching operation in accordance with one of the first control signal and a second control signal input thereto to control an output voltage based on the input voltage, and a control circuit to control the first and second switching elements to perform the switching operations in one of a normal operation mode and a light load operation mode in which a current consumed by a load connected to the switching regulator is smaller than a current consumed in the normal operation mode, and control the first switching element to be turned off in the light load operation mode.

Method and apparatus for power supply controlling capable of effectively controlling switching operations

A DC&#x2014;DC converter is disclosed that includes a constant voltage circuit outputting a first voltage, a charge pump circuit outputting a second voltage, a current detection circuit converting the output current of the constant voltage circuit into a third voltage and outputting the third voltage, a first detection circuit detecting the first voltage and outputting a first detection voltage proportional thereto, a first overcurrent protection circuit comparing the third voltage and the first detection voltage and reducing the output first voltage and current of the constant voltage circuit when the third voltage exceeds the first detection voltage, a second detection circuit detecting the second voltage and outputting a second detection voltage proportonal thereto, and a second overcurrent protection circuit comparing the third voltage and the second detection voltage and reducing the output first voltage and current of the constant voltage circuit when the third voltage exceeds the second detection voltage.

DC&#x2014;DC converter

An overcurrent limitation circuit for use in a direct current stabilization electric power supply circuit controls and drives an output transistor to output a constant voltage in accordance with a difference between a reference voltage and a voltage proportional to the output voltage. The overcurrent limitation circuit includes a proportional output current generating device for generating a current proportional to a current flowing through the output transistor, a current/voltage-converting device for converting an output current flowing from the proportional output current generating device into a voltage, and a switching device configured to supply the current/voltage converting device with the output current from the proportional output current generating device when the output voltage is higher than a prescribed level, and interrupts the supplying when the output voltage is lower than the prescribed level. A control device is provided so as to control the output transistor to output a current in accordance with an output voltage at a current supplying point of the proportional output current generating device.

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Osaka-fu, Japan

Tomonari Katoh