Korea Advanced Institute of Science and Technology

Baek-Min Lim

Jeong-Il Seo

Sang-Gug Lee

Young-Seok Noh

Hyun-Mo Gu

A current mode hysteretic buck converter employing an auto-selectable frequency locking circuit is disclosed. The auto-selectable frequency locking type buck converter include a current mode hysteretic buck converter for converting an input DC voltage into a lower DC voltage, and a frequency locking unit for locking a switching frequency of the current mode hysteretic buck converter wherein the switching frequency is locked through adjusting a locking value of the switching frequency to be a predetermined value according to a size of a load. The buck converter is, based on the current mode hysteretic control, related to a circuit that locks the switching frequency of the converter to reduce the difficulty of designing electromagnetic interference (EMI) filters in the converter. In addition, the buck converter can improve the efficiency at light load by adjusting the switching frequency which is locked according to the load current.

Current mode hysteretic buck converter with auto-selectable frequency locking circuit

A power management device according to example embodiments includes a self-startup circuit including an oscillator and a voltage multiplier to generate a start-up voltage in a first start-up period based on an input voltage, a boost converter to alternately charge the start-up voltage and an output voltage within a start-up voltage range during a second start-up period and to charge only the output voltage during an operation period, a controller to control the self-startup circuit and the boost converter based on a magnitude of the start-up voltage, a voltage charger including a start-up voltage capacitor and an output voltage capacitor, and a shared inductor connected between the input node and a common input node. The shared inductor operates as a part of the oscillator during the first start-up period and a part of the boost converter during the second start-up and operation periods.

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Daejeon, South Korea

Baek-Min Lim