Rohm Co., Ltd.

Takuya Ishida

Seiji Takenaka

Minehisa Yamamoto

In a charge pump circuit, the slew rate at which a clock signal is fed to charge transfer transistors is changed according to the output voltage. This configuration helps alleviate rush currents at start-up without unduly lowering efficiency.

Charge pump circuit and electric appliance therewith

A floppy disk apparatus improves power efficiency and quietness by commencing rotation of a stepping motor in a smooth fashion. The floppy disk apparatus includes an interface control circuit that outputs, in accordance with an instruction from a host apparatus, a first step pulse signal, step pulse period signals that indicate the period of the first step pulse signal and that are output before the first step pulse signal and a direction signal, and a floppy disk control circuit that generates a second step pulse signal delayed by a predetermined time from the first step pulse signal in accordance with the step pulse period signal, that generates a first signal that toggles in synchronization with the first step pulse signal and a second signal that toggles in synchronization with the second step pulse signal, and that outputs the first and second signals as control signals in accordance with the direction signal.

Floppy disk apparatus

In a motor driver furnished with a function of controlling the driving of a motor through negative feedback control of the current supplied to the coil of the motor, the motor driver permits the setting of a target value of the current that is negatively fed back, and sets the target value in such a way that the target value at a time point when the current starts being supplied to the coil of the motor is smaller than the target value after the current starts being supplied to the coil of the motor. This permits the current flowing through the coil to increase more gradually than in conventional circuit configurations in which the target value is fixed at the maximum value thereof before the current starts being supplied to the coil of the motor. Thus, it is possible to suppress overshooting and oscillation in the current flowing through the coil and oscillation in the voltage across the coil, and thereby reduce noise.

Motor driver

A semiconductor integrated circuit device has a data reproduction circuit for reproducing data read by a head from a magnetic disk during a read operation, a data output circuit for outputting reproduced data obtained as an output of the data reproduction circuit to an external circuit, and an erase current control circuit for controlling an erase current supplied to the head during an erase operation. During an erase operation, the data reproduction circuit is kept deactivated. During transition from an erase operation to a read operation, the data reproduction circuit is activated after the erase current is turned off, and thereafter the data output circuit is activated.

Semiconductor integrated circuit device for use in a magnetic disk drive with reduced recovery time between operations

In a semiconductor integrated circuit device, after electric power starts being supplied thereto, when a control circuit 2 is turned on, a test signal is fed in via a clock output terminal 6. At this time, an on/off control signal is at a low level, which causes a controller 14 to feed a low-level signal through a buffer 17 to the gate terminal G of a latch circuit 15, and thus the test signal fed through a buffer 9 to the input terminal D of the latch circuit 15 is fed from the output terminal Q thereof to the controller 14. Having received the test signal, the controller 14 recognizes establishment of a test mode and turns the on/off control signal to a high level. This causes the latch circuit 15 to stop operating, and thus the controller 14 feeds a clock through an AND circuit 16 and a buffer 8 to a clock output terminal 6 for external output.

Magnetic recording/reproducing apparatus and semiconductor integrated

A semiconductor integrated circuit device for use in a disk drive apparatus has a stepping motor driver for feeding an electric current to a stepping motor, a temperature monitoring circuit for monitoring the temperature due to the heat generated by the stepping motor driver, a signal processing circuit for processing an analog signal communicated to write or read data to or from a magnetic data recording medium, and a controller for controlling the stepping motor driver and the signal processing circuit. The signal processing circuit is arranged between the stepping motor driver and the temperature monitoring circuit. This minimizes the variation of the ground level of the temperature monitoring circuit that occurs every time the stepping motor driver is turned on or off and thereby makes accurate monitoring of the temperature possible.

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Kyoto, Japan

Takuya Ishida