Rohm Co., Ltd.

Yujiro Okamoto

Masashi Nagasato

Shingo Hokuto

A multi-output power supply device () comprises a first power supply () for outputting a first output voltage (VDCO); a second power supply () for outputting a second output voltage (VDCO); and a reset circuit () for detecting an abnormality of the first output voltage (VDCO) and for outputting a first reset signal (XRESET) to forcibly stop the output operation of the second power supply ().

Multi-output power supply device and electric apparatus using same

A magnetic recording and reproducing device is a hard disk device which writes information onto a magnetic disk (not shown), or reads information therefrom, and includes: a reproducing head; a recording head; and a magnetic head driving circuit. The magnetic head driving circuit is a circuit, by which driving of the reproducing head and the recording head is controlled, and onto which the reproducing head, a recording head driving circuit, a control unit, and a variable impedance element are integrated. This magnetic head driving circuit is switched on a time division base to a read mode during reproducing operation, and to a write mode during recording operation. The control unit reduces the impedance of the variable impedance element during the write mode.

Magnetic head driving circuit with protection function

Conventionally, in an electrical device having an output transistor for limiting an input current to produce an output current and a bypass capacitor connected to the output side of the output transistor, the waveform of the current that charges the bypass capacitor cannot be adjusted without varying the capacitance of the bypass capacitor. In an electrical device embodying the invention, the waveform of the current that charges the bypass capacitor can be adjusted by varying the limit value of the output current without varying the capacitance of the bypass capacitor.

Current limiting device and electrical device incorporating the same

A magnetic recording apparatus has a magnetic head for writing data to a magnetic disk, a writing circuit for feeding a current to the magnetic head, a controller for controlling the operation of the writing circuit, and a temporary shutoff circuit for shutting off the current temporarily while the operation of the controller is in a transient period. The writing circuit has a first transistor, which is connected to the magnetic head. The temporary shutoff circuit has a second transistor so as to temporarily deactivate and thereafter activate the first transistor when electric power starts being supplied by pulling into the second transistor the transient current resulting from variation in the base voltage of the second transistor as a result of the parasitic capacitor present at the base of the second transistor being charged when electric power starts being supplied.

Magnetic recording apparatus with a magnetic head for writing data to a magnetic disc

A magnetic reproducing apparatus uses a magnetic head to read data recorded on a magnetic recording medium. The signal reproduced by the magnetic head is, in a reading circuit, amplified by an amplifier circuit. A compensation circuit compares the bias voltage across the magnetic head with a reference voltage to detect variation in the bias voltage and compensates for the variation in accordance with the detection result. In the magnetic reproducing apparatus, the amplification factor of the amplifier circuit is set by a control signal fed in via a single switching terminal, and the reference voltage is set in a manner interlocked therewith.

Magnetic reproducing apparatus that limits distortion of an output signal with increased amplification

A terminating circuit including a pair of diodes connected to have polarities opposite to each other is provided across a magnetic head. When the potential difference across the magnetic head is drastically changed to be equal to or higher than the breakdown voltage of the diodes at the time of switching of a writing current, either one of the diodes breaks down, so that a part of the writing current flows out through the terminating circuit. As a result, ringing due to the drastic change is removed. When the potential difference across the magnetic head is lower than the breakdown voltage of the diodes, since either one of the diodes is reversely biased, the resistance of the terminating circuit is maintained high. Consequently, within this range, the writing current flowing to the magnetic head never flows out to the terminating circuit. As a result, the deterioration of the reading and writing characteristics is prevented.

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Kyoto, Japan

Yujiro Okamoto