A High-Efficiency Dual-Mode DC–DC Converter With a Low-Cost Seamless Transition Scheme

A low-complexity pulsewidth modulation/ pulse skipping modulation (PWM/PSM) dual-mode buck dc–dc converter is proposed. The converter operates in PWM with a 1.5-MHz switching frequency in heavy load scenarios and switches to PSM with a sliding switching frequency under light load conditions, ensuring a high efficiency over a wide load range. Based on peak current mode control, only one simple voltage detector is required to regulate the converter for different loads, which significantly reduces the circuit complexity for a seamless mode transition. Fabricated in 180-nm BCD technology, the total chip area is less than 0.28 mm² and the quiescent current is lower than 90 μA. The converter achieves the efficiencies up to 93.65% for PWM scheme and more than 80.61% in PSM mode, respectively, with the input voltage of 4.0–5.5 V and the load current up to 1.2 A. Additionally, the presented design achieves a line regulation less than 0.18% and a load regulation lower than 0.98%, and also accomplishes a voltage variation of 3.49%/A for load current transient response and gets an attractive figure of merit.