Simple Low-Cost Hysteretic Controller for Single-Phase Synchronous Buck Converters

TLDR: In this article, a simple low-cost control architecture for low-voltage hysteretic regulators supplying loads with low-to-medium current consumption is presented, where the closed-loop output impedance can be designed to be resistive and the switching frequency can be adjusted to be independent of the output impedance requirement so that the load transient response and the efficiency can be optimized separately.

Abstract: This paper presents a simple low-cost control architecture for low-voltage hysteretic regulators supplying loads with low-to-medium current consumption. Only two sensed voltages, a passive filter network and a hysteretic comparator are required to implement the main control functions: the output voltage regulation and the adaptive voltage positioning. This paper also shows that other previously reported low-cost control solutions have an important design tradeoff between load transient response and efficiency. In the proposed controller, the closed-loop output impedance can be designed to be resistive and the switching frequency can be adjusted to be independent of the output impedance requirement so that the load transient response and the efficiency can be optimized separately. Experimental results validate the performance of the proposed controller (i.e., a load transient response with insignificant output voltage overshoot and selectable switching frequency independent of the output impedance requirement).