Author(s)

Yanqiu Duan, Jian Fang, Rongxing Lai, Xing Tong, Bo Zhang

Corresponding Author

Jian Fang

ABSTRACT

A control method named average current-detection and hysteresis turn-off (ACHT) with enhanced adaptive off-time (EAOT) in non-isolated buck LED driver is proposed in this paper to achieve accurate constant current. The proposed control method is implemented by the ACHT loop which is utilized to control on-time and the EAOT loop which is utilized to generate an adaptive off-time (AOT). Five conventional control methods are thoroughly analyzed and compared. Analysis and results prove that the proposed ACHT with EAOT can detect valley current based on low-side sensing method, work stably, output average current with high precision, and avoid the current spike without introducing leading-edge blanking (LEB). The design was implemented with TSMC’ 1μm 700V BCD process.

KEYWORDS

Constant Current Control Method, Valley Current Detection by Side Sensing Method, Accurate Constant Current