Current-Slope-Controlled Adaptive-On-Time DC-DC Converter with Fixed Frequency and Fast Transient Response

An integrated fixed frequency adaptive-on-time DC-DC converter with fast transient response is presented. To achieve fixed frequency, the slope information of the inductor current is employed to adjust the on-time and keep the switching frequency constant at 1MHz to within 10% variation across the whole input/output and loading ranges. An integrated boost converter with an input voltage of 1.8V to 2.4V and a regulated output voltage between 3.0V and 3.6V was implemented with a 0.35 mu m CMOS process. Simulation results show that the switching frequency variation has similar to 40% and similar to 30% improvement over the traditional input/output voltage controlled adaptive-on-time technique when the load current changes from 0.1A to 0.8A and the inductor ESR changes from 0 Omega to 0.2 Omega, respectively. The load transient response time is about 20 mu s when the load current changes from 200mA to 800mA