Rohm Co., Ltd.

Joji Noie

Tomofumi Mishima

Masahiro Nakamura

Yuki Gohara

Yuji Saegusa

A bridge circuit includes a high-side transistor connected between a power supply terminal and an output terminal, and a low-side transistor connected between the output terminal and a ground terminal. A high-side pre-driver and a low-side pre-driver drive the high-side transistor and the low-side transistor. A first transistor is connected between the output terminal and the ground terminal in a manner to form the regenerative path parallel to the low-side transistor. In a regenerative state in which a current sinks from the output terminal, a regenerative control circuit controls the voltage of a control terminal of the first transistor in a manner that an output voltage of the output terminal approaches a target voltage higher than the power supply voltage of the power supply terminal by a first voltage width.

Drive circuit of three-phase DC motor and electronic device using thereof

The present invention relates to a fan motor driving circuit, a driving method, and a cooling device and an electronic machine using the same. The present invention provides a motor driving circuit capable of suppressing strain on coil current and/or reducing noise. A control circuit a control circuit switches an output phase of an H-bridge circuit based on a Hall signal, and in a soft switching duration (Tss) that starts before and ends after the output-phase switching, slowly varies a duty ratio (DUTY) of an output voltage (V) of one leg of the H-bridge circuit over time, and meanwhile, varies a duty ratio (DUTY) of an output voltage (V) of another leg of the H-bridge circuit in an opposite direction with respect to the duty ratio (DUTY) of the output voltage (V) of the one leg.

Fan motor driving circuit, driving method, and cooling device and electronic machine using the same

A TH terminal receives an analog control voltage Vwhich indicates a rotational speed. With a first platform, a capacitor and a discharging resistor are connected in parallel between an OSC terminal and the ground. A charging resistor and a first switch are arranged in series between the OSC terminal and a reference voltage line via which a stabilized voltage is supplied. When an oscillator voltage Vthat occurs at the OSC terminal reaches an upper-side threshold V, a switching circuit turns off the first switch. When the oscillator voltage Vfalls to a lower-side threshold value V, the switching circuit turns on the first switch. The oscillator voltage Vis compared with the voltage at the TH terminal, so as to generate a pulse-modulated control pulse S

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Kyoto, Japan

Joji Noie