A Novel Buck Converter with Constant Frequency Controlled Technique

Hsiao-Hsing Chou,Hsin-Liang Chen

doi:10.3390/en14185911

Hsiao-Hsing Chou, Hsin-Liang Chen

Open Access

https://doi.org/10.3390/en14185911

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Abstract

This paper presents a buck converter with a novel constant frequency controlled technique, which employs the proposed frequency detector and adaptive on-time control (AOT) logic to lock the switching frequency. The control scheme, design concept, and circuit realization are presented. In contrast to a complex phase lock loop (PLL), the proposed scheme is easy to implement. With this novel technique, a buck converter is designed to produce an output voltage of 1.0–2.5 V at the input voltage of 3.0–3.6 V and the maximum load current of 500 mA. The proposed scheme was verified using SIMPLIS and MathCAD. The simulation results show that the switching frequency variation is less than 1% at an output voltage of 1.0–2.5 V. Furthermore, the recovery time is less than 2 μs for a step-up and step-down load transient. The circuit will be fabricated using UMC 0.18 μm 1P6M CMOS processes. The control scheme, design concept and circuit realization are presented in this paper.

Highlights

Power converter brings convenience to human life [1,2,3] and plays an indispensable role in various portable devices
The main modulation methods can be divided into two categories: pulse width modulation (PWM) and pulse frequency modulation (PFM) [4,5]
Based on the above reasons, this paper proposes a novel constant frequency control scheme to maintain the switching frequency constant, instead of phase lock loop (PLL)

Summary

Introduction

Power converter brings convenience to human life [1,2,3] and plays an indispensable role in various portable devices. Their applications include smartphones, tablet computers, the internet of things (IoT) and other electronic products. The power source of these products is the battery. In order to extend the battery life, the products will enter a standby mode when they are not operating. High power efficiency is a critical issue in a wide load range. The main modulation methods can be divided into two categories: pulse width modulation (PWM) and pulse frequency modulation (PFM) [4,5]

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