A Battery-Input Three-Mode Buck–Boost Hybrid DC–DC Converter With 97.6% Peak Efficiency
Shuangxing Zhao, Chenchang Zhan, Yan Lü
Abstract
This article presents a three-mode non-inverting buck–boost hybrid converter (3M-BBHC) suitable for mobile devices powered by lithium-ion (Li-ion) batteries. The proposed 3M-BBHC can work in buck, boost, or buck–boost mode, and it can switch the operation mode smoothly with a small ripple as the input voltage changes. Compared with the conventional non-inverting buck–boost converter (CBBC), the proposed 3M-BBHC still has only four power switches with a flying capacitor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C_{{F}}$</tex-math> </inline-formula> ) added. The number of switches conducting current in series with the inductor is reduced from 2 (in CBBC) to 1 (in 3M-BBHC) to decrease the conduction and switching losses. The inductor connects to the input terminal, which means the 3M-BBHC has a continuous input current and thus low electromagnetic interference (EMI). Besides, in buck mode, the inductor current is always smaller than the output current, which decreases the inductor dc resistance (DCR) conduction loss. The 3M-BBHC was fabricated in a standard 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m CMOS process, using only 3.3-V devices to further reduce the losses. A 97.6% peak efficiency is measured by using a 2.2- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> H inductor with 110-m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega$</tex-math> </inline-formula> DCR, a 10- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> F <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C_{{F}}$</tex-math> </inline-formula> , a 10- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> F output capacitor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C_{{O}}$</tex-math> </inline-formula> ), and a 2-MHz switching frequency. Its input voltage ranges from 2.7 to 4.2 V, and it can deliver an output current of 100–800 mA at 3.3-V regulated output voltage.