Time domain CCM/DCM boundary detector with zero static power consumption for integrated high-efficiency step-down DC/DC converters

This paper describes a circuit allowing accurate detection of the continuous (CCM) and discontinuous (DCM) conduction mode boundary. It is suitable namely for very low power integrated DC/DC converters such as the buck or boost. The zero power consumption of this critical block enables to greatly improve the light load power efficiency, and minimize the silicon area. Detection uses a time shift of the power-stage output voltage, which depends on the inductor current value and its polarity. Detector circuit is realized with a digital latch comparator containing only a few digital gates. The paper contains description of the method, example of circuit implementation, and post-layout simulation of integrated detector in 0.13μm CMOS technology, allowing to obtain several mA detection accuracy