A High-Efficiency Fast-Transient Double Hysteretic Control Point-of-Load Converter

As portable devices become increasingly sophisticated, the demands for their power management in terms of high power-efficiency and fast-transients are congruously higher. We present herein a Point-of-Load converter (PoL) with two interesting features. One, compared to state-of-the-art PoLs with comparable transient performance, it features higher power-efficiency across most of the load range. Two, compared to state-of-the-art PoLs with similar power-efficiency, it features faster transients. These attractive features are achieved by our novel proposed Double Hysteretic Control that integrates a Voltage-Mode Hysteretic Controller (VMHC) and a CurrentMode Hysteretic Controller (CMHC). The modus operandi of the VMHC operates its Discontinuous-Conduction-Mode and Continuous-Conduction-Mode without a mode-selection circuit to derive high power-efficiency. The CMHC combines two conventional current-mode controls to prolong on-time and offtime extensions, enabling fast transients. On the basis of measurements on a monolithic prototype, the power-efficiency is >90% across the 2mA-3A load range with a peak-efficiency of 96.1%. The voltage undershoot and overshoot are 70mV and 40mV with recovery times of 3μs and 2μs in response to 2.7A step-up and step-down load current transients (1A/μs slew-rate), respectively. Compared to state-of-the-art designs, our PoL optimizes both power-efficiency and transient response, features the best Figures of Merit and is highly competitive.