Fujitsu Corporation

Fujitsu Semiconductor Limited

Spansion LLC.

Mayo Kitano

Masatoshi Kokubun

Takashi Matsumoto

Tsuyoshi Moribe

Masayuki Yonekawa

Yasuhiro Korogouchi

Hideki Sumi

A charging circuit includes a monitoring part configured to monitor a battery voltage applied to a battery and configured to output an overvoltage signal when the battery is in an overvoltage condition a protection part configured to electrically disconnect the battery from an adaptor when receiving the overvoltage signal, and a switch which, when the battery is electrically disconnected from the adaptor, switches a monitoring node for an adaptor voltage outputted from the adaptor, from a supply node of the battery voltage to a supply node of a system voltage, which is applied to a system electrically connected with the battery and the adaptor, based on the overvoltage signal to cause a control command for controlling the adaptor voltage based on the system voltage to be outputted.

Charging circuit, charging apparatus, electronic equipment and charging method

A voltage control method includes producing an error signal based on a difference between a reference signal and an adaptor voltage and an adaptor current corresponding to the adaptor voltage, regulating, based on the error signal, the adaptor voltage, comparing a reference voltage to a voltage proportional to a potential corresponding to an identifying voltage corresponding to the adaptor voltage, detecting, based on the comparison result, whether or not a couplable external power source is suitable, and setting based, on the detection result, a potential corresponding to the identifying voltage.

Electronic device, detection circuit and voltage control method

A voltage control oscillation (VCO) circuit and an adjusting method for the same, which enables an adjustment for suppressing the dispersion of the output characteristic in spite of the manufacture-related dispersion of element characteristics, using a simple circuit configuration, are provided. A low-pass filterand a high-pass filterare composed of the elements that have the same structure as elements composing the VCO circuit, and a prescribed correlation is established between both elements. A corrective elementis connected in parallel to a main element, in which an oscillation frequency control signal VT is input, in the VCO circuit. Respective frequency-gain characteristic lines of the low-pass/high-pass filtersandhave gradients reverse to each other and cross at a target gain TG. When the capacitance value lowers in dispersion, the level of an output signal SLbecomes higher than that of an output signal SHat a reference frequency fREF to form an output level difference LD. In response, an adjusting signal VCNTis output in correspondence to the output level difference LDto lower an oscillation frequency fVCO.

Voltage control oscillation circuit and adjusting method for the same

An analog filter circuit in which filter characteristic deviation can be adjusted with simple circuitry and its adjustment method can be provided. The analog filter circuit includes a low pass filter and a high pass filter and output signals of both filters are input to a comparison and adjustment section from which an adjustment signal is fed back to the low pass and high pass filters and also input to a predetermined-band pass filter having predetermined correlation to the low pass and high pass filters. The low pass and high pass filters are tuned so that the frequency-gain characteristic line in an attenuation band of the low pass filter linearly falls, while that line of the high pass filter linearly rises, both the lines crossing at a reference frequency. When filter characteristic deviation occurs, it is adjusted to compensate gain difference between the output signals produced by filtering the reference signal with a reference frequency and, accordingly, the predetermined-band pass filter is adjusted to its desired filter characteristic.

Analog filter circuit and adjustment method thereof

Oscillators have capacitors, respectively, whose capacitances change according to an external force and generate first oscillating signals according to the capacitances. Each of the capacitors is disposed, for example, between a substrate and a mass body that is movably disposed to face the substrate and oscillates in a direction perpendicular to the substrate. A detecting unit detects a relative difference between the capacitances of the capacitors as a difference between frequencies of the first oscillating signals. An angular speed or acceleration applied in a horizontal direction of the substrate is calculated according to the frequency change detected by the detecting unit. Therefore, a capacitance difference detecting circuit and a MEMS sensor that detect a minute change in the capacitances of the two capacitors caused by the external force are formed.

Growing community of inventors

Kasugai, Japan

Mayo Kitano