LAUSR

A mixed-ripple adaptive on-time controlled non-inverting buck-boost dc-dc converter with novel adaptive-window-based mode selector is proposed, and no compensator is required in the control circuits. For achieving high conversion efficiency, the non-inverting buck-boost dc-dc converter only works in the buck or boost modes, not the buck-boost mode. Moreover, with the proposed mode selector, smooth transition between buck mode and boost mode can be achieved. Besides, it makes the efficiency reach its maximum when the input voltage approaches the output voltage. The proposed chip was implemented by using a $0.35~\mu \text{m}$ CMOS 2P4M 3.3V/5V mixed-signal polycide process. The input voltage may range from 2.5 to 5.0 V, and the output voltage is regulated at 3.3V. According to the measured results, the maximal conversion efficiency is 97.8%.