A power-switch thermal limiting technique for current-mode monolithic DC-DC converters

• Published in: International journal of electronics and communications Vol. 111; p. 152797
• Main Authors: Xiao, Zhiming, Wang, Yu, Zhao, Guangshu, Xu, Yitao, Lu, Chao, Hu, Weibo
• Format: Journal Article
• Language: English
• Published: Elsevier GmbH 01.11.2019
• Subjects: Current limit; Current-mode control; DC-DC converters; Thermal limitation; DC-DC converters; Thermal limitation; Current limit; Current-mode control
• ISSN: 1434-8411; 1618-0399
• DOI: 10.1016/j.aeue.2019.06.022

This paper presents a power-switch thermal limiting technique for peak current-mode DC-DC converters to achieve maximized load current deliverability under a fixed thermal constraint. The inductor current limit of the converter is adaptively set based on the sensed switching duty-cycle to maintain a fixed power consumption limit across a wide input voltage range. The proposed current limiting circuit exhibits a fast-transient response and the chances of power-switch overheating is minimized. Since the temperature rise of the converter chip is also a function of the heat-conduction conditions such as the package type, the PCB layout, and the ambient temperature, the proposed architecture allows the power limit to be adjustable through a single off-chip resistor. Compared with a conventional switching converter which sets the inductor current limit to be constant across the entire input voltage range, the proposed approach achieves a higher available load current, especially with a higher input voltage under the same thermal constraint. In the proposed boost converter with an allowable temperature rise of 40°C, the proposed converter achieved 46% more available load current compared with the conventional one at the highest input voltage.