Abstract: A DC-DC converter according to the present invention includes a monitoring circuit which monitors an output signal of a mode comparator and which outputs a mode change detection signal when the output of the mode comparator has output a light load mode signal, and a clamp circuit which is connected between power supply and ground and which changes a voltage at a first end of a filter circuit toward a preset prescribed voltage according to the mode change detection signal.

Abstract: A DC-DC converter according to the present invention includes a monitoring circuit which monitors an output signal of a mode comparator and which outputs a mode change detection signal when the output of the mode comparator has output a light load mode signal, and a clamp circuit which is connected between power supply and ground and which changes a voltage at a first end of a filter circuit toward a preset prescribed voltage according to the mode change detection signal.

Abstract: A barcode scanner comprising a laser driving circuit to drive a laser by a pulse signal generated by an oscillator, a preamplifier to amplify a voltage of a barcode signal from a photodetector corresponding to a reflected light from a barcode scanned by a light output of the laser driven by the pulse signal, a high-pass filter to remove a direct current component contained in an output signal of the preamplifier, a variable gain amplifier which controls an amplification gain of an output signal of the high-pass filter and performs automatic gain control to set an output level almost constant, a synchronous detector to detect a pulse signal contained in an output signal of the variable gain amplifier in synchronization with the output pulse of the oscillator, and a binarization circuit to binarize an output signal of the synchronous detector.

Abstract: Disclosed is a barcode scanner comprising a laser driving circuit to drive a laser by a pulse signal generated by an oscillator, a preamplifier to amplify a voltage of a barcode signal from a photodetector corresponding to a reflected light from a barcode scanned by a light output of the laser driven by the pulse signal, a high-pass filter to remove a direct current component contained in an output signal of the preamplifier, a variable gain amplifier which controls an amplification gain of an output signal of the high-pass filter and performs automatic gain control to set an output level almost constant, a synchronous detector to detect a pulse signal contained in an output signal of the variable gain amplifier in synchronization with the output pulse of the oscillator, and a binarization circuit to binarize an output signal of the synchronous detector.

Abstract: A delay-time variable filter delays an input signal by a desired time according to a control signal from a control input node and outputs the delayed input signal, and a positive feedback loop circuit changes the output signal (sinusoidal wave signal) from this filter, and provides a positive feedback of the binary pulse signal to the input side of the filter at a desired level for carrying out an oscillation. This positive feedback loop circuit includes a circuit for changing the signal into a binary signal and providing a positive feedback of the binary signal to the input of the filter by limiting the signal at a desired amplitude. As the delay-time variable filter, a quartic Butterworth low-pass filter is used, for example. As the positive feedback loop circuit, there is used a voltage comparator circuit that changes an input signal into a binary signal and outputs a pulse signal of a desired amplitude.

Abstract: In this filter circuit, the emitter of a transistor Q1 is connected to the collector of a transistor Q2, and the base of the transistor Q2 is connected to the emitter of a transistor Q3 and the collector of a transistor Q4. The base of the transistor Q4 is connected to the collector of the transistor Q2. A capacitor C1 is connected between the emitters of the transistors Q2 and Q4, and a capacitor C2 is connected between the collectors of the transistors Q2 and Q4. With this arrangement, the filter circuit consumes a small power, is hardly influenced by the parasitic capacitance, can operate at high frequencies, and has a wide dynamic range.

Abstract: A circuit and method for detecting an abnormality in a recording head, wherein a voltage detection circuit detects a counter electromotive voltage generated across the two terminals of a recording head to which a recording current is supplied from a recording circuit; a processing circuit generates the maximum, minimum, and mean voltages from the counter electromotive voltage; a discrimination circuit using these voltages determines whether an abnormality occurs in the recording head. An output circuit outputs the result. With this operation, an abnormality in the recording head having two terminals in an MR head can be detected with a high precision.

Abstract: A magnetic disk drive system for writing data into a disk-shaped magnetic medium and reading data stored therein, comprises a first terminal, a second terminal, and at least one third terminal, a composite head unit including an inductive write head and at least one magnetoresistive read head which are connected in series between the first and second terminals, and at least one common connection node connected to the at least one third terminal, and a driving circuit connected to the first through third terminals.