Abstract—Class-D amplifier has been a popular device because of its high power efficiency. However, its ability of high power delivery also brings about over-temperature problem caused by consuming large power-loss over a long time. This paper therefore presents a control method to dynamically reduce the total power-loss of multilevel class-D amplifier according to the value of integrated temperature sensor. The driving (static) power-loss is reduced by limiting the driving current which can be achieved by reducing the output levels of the amplifier. In addition, the switching (dynamic) power-loss is diminished by segmenting the power transistors and gate drivers and selectively enabling parts of them according to the power demand. Therefore, the total power-loss of the amplifier is well controlled and reduced in order to prevent over-heating itself. Under the protection scheme, experimental results show that the total power-loss (excessive heat) and corresponding temperature difference on package can be reduced to only 15% of maximum value which demonstrates the effectiveness of proposed scheme.

Index Terms—Over-temperature protection, power-loss control, multilevel technique, class-D amplifier, PWM.

B. S. Hsieh is with the Graduate School of Engineering Science and Technology, National Yunlin University of Science & Technology (NYUST), Yunlin 640, Taiwan, R.O.C. (e-mail: g9610810@yuntech.edu.tw).
C. W. Lin is with the Department of Electronic Engineering, National Yunlin University of Science & Technology (NYUST), Yunlin 640, Taiwan, R.O.C. (e-mail: linwei@yuntech.edu.tw).