Asahi Kasei Microsystems Co., Ltd.

Asahi Kasei Microdevices Corporation

Tamotsu Nagashima

Koji Tomioka

An integrated circuit is provided, including an AD converter; a DC-DC converter converting a received first voltage into a second voltage and providing the second voltage as a power supply voltage of the AD converter; a control part controlling the AD converter and the DC-DC converter. The DC-DC converter includes a first switching element; a second switching element having one end coupled to a reference potential and the other end coupled to one end of the first switching element; a coil coupled to a connection point of the two switching elements; and a current detection part detecting a current flowing to the coil. The control part turns off the first switching element and turns on the second switching element, and after the current detected by the current detection part becomes equal to or smaller than a reference current value, turn off the second switching element to operate the AD converter.

Integrated circuit and motor device

A spread spectrum clock generator is provided which improves the spread spectrum effect with little increasing the circuit cost by modifying the shape of a triangular wave used for frequency modulation by a simple method. The output signal of the modulation waveform generating circuit has such a modulation waveform as indicated by solid lines in FIG.A. The modulation waveform is input to a VCO (voltage-controlled oscillator). In response to the modulation waveform, the oscillation frequency of the VCO is modulated, and the output clock that varies its frequency as illustrated in FIG.B is obtained. The frequency transition of the output clock involves such temporal variations as indicated by solid lines in FIG.C.

Waveform generating circuit and spread spectrum clock generator

A waveform generating circuit is provided which generates a modified triangular wave signal suitable for being input to a frequency modulation circuit such as a voltage-controlled oscillator (VCO). The waveform generating circuit includes a triangular generator, an offset generator for generating first and second offset component signals, a combiner for adding the triangular wave signal generated by the triangular wave generator and the offset component signals, and an output for delivering an output signal resulting from the addition by the combiner.

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Tokyo, Japan

Tamotsu Nagashima