An IAOT controlled current-mode buck converter with RC-based inductor current sensor

Abstract

An improved adaptive-on-time (IAOT) controlled current mode buck converter with RC-based current-sensing circuit and internal softstart property is presented in this paper. First, the inductor current is sensed by a resistor-capacitor (RC) network, which can fully sense the trend of inductor current with high accuracy. Second, an IAOT control circuit is used to realize the on-time of the power switch adaptively changing with the operation conditions. In addition, the overshoot (undershoot) voltages are reduced by making T ON adaptively shorter (longer) during the unloading (loading) transient due to the IAOT control. Third, soft start operation protects the circuit from large in-rush current during startup of the converter. Fourth, the proposed buck converter was implemented with standard 0.18-µm CMOS process. Simulation outcomes have shown an input voltage of 5 V, when the output voltage is ranging from 1.2 V to 3.6 V, with a maximum conversion efficiency of 98% (heavy loads) and 94% (light loads), making the buck converter quite useful in power management ICs.

A wide input voltage range DC-DC Buck converter with dynamically modified ZCD circuit

“…Fig. 1 is the circuit of the synchronous buck circuit [20,21,22,23,24]. From the above analysis, it can be known that the circuit will operate in the DCM mode under light load operating conditions.…”