Rohm Co., Ltd.

Yoju Imamura

Yuhei Yamaguchi

Tetsuo Tateishi

Yosuke Fukumoto

Genki Tsuruyama

Hiroto Oshita

Daisuke Uchimoto

Naoki Inoue

A pulse control devicecomprises: a switch output unitwhich generates a pulse output voltage Vo from a direct-current input voltage Vi and supplies the pulse output voltage Vo to a load (such as a relay coilof a mechanical relay); a low-pass filter unitwhich receives a feedback input of the pulse output voltage Vo and generates a feedback voltage Vfb; and an output feedback control unitwhich receives an input of the feedback voltage Vfb and controls the switch output unitso that an average value of the pulse output voltage Vo becomes constant. The low-pass filter unitmay be configured without a coil.

Pulse control device

A control IC controls a switching power supply configured to supply a driving voltage Vout to one terminal of an LED string which is driven in an intermittent manner. A sample-and-hold circuit performs sampling of a detection voltage Vs that corresponds to a driving voltage Vout in the on period, and holds the sampled detection voltage Vs in the off period. In the off period, a pulse modulator generates a pulse signal having a duty ratio adjusted such that a hold detection voltage VsH output from the sample-and-hold circuit matches the detection voltage Vs. A driver drives a switching transistor according to the pulse signal.

Control circuit for switching power supply

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Kyoto, Japan

Yoju Imamura