A Single Li-Ion Battery Powered Buck Converter With >90% Efficiency Over 10-μA to 500-mA Loading Range by Utilizing Compensator-Based Built-In Mode Tracking Technology

An ultralow quiescent current dual-mode dc – dc buck converter is presented in this article to achieve high efficiency over a wide load range for Internet of Thing (IoT) applications. In medium and heavy load conditions, the valley-current mode (VCM) with adaptive on-time (AOT) is employed to guarantee loop stability and seamless transition between pulsewidth modulation (PWM) and pulse-frequency modulation (PFM). A hiccup mode (HM) is proposed to minimize the power consumption of control circuits in light load conditions. Based on the compensator in the VCM, a built-in mode tracking technology is proposed to achieve the predictable and seamless mode transition without load current sensing circuits. Implemented in a 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 BCD technology, the proposed converter has an efficiency higher than 90% over 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> A to 500-mA loading range within the supply range of a single lithium-ion battery. Under a 2.4–5.5-V input voltage and 0–1-A loading current range, the output ripple is less than 20 mV. When the load current steps from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.4~{\mu }$ </tex-math></inline-formula> A to 200 mA within 10 ns, the output undershoot is 152 mV.