The increasing demand for high-definition audio in mobile platforms is creating the necessity of adequate operation limits for smart amplifiers to safely maximize the power delivered to micro-speakers. The maximum voice-coil temperature (Tmax) is an important parameter for protection algorithms that prevent damage. Standard tests used by micro-speaker suppliers to specify Tmax provide a conservative estimate referred to voice-coil materials. Other tests consider the rated noise power, which is a specification obtained by rigorous lifetime tests. In this work, we contrasted the performance of micro-speakers when using values of Tmax in datasheets with values of voice-coil temperatures obtained when micro-speakers operated at their specified rated power. The evidence found is used to recommend power-based thermal limits that avoid over-protection.
Authors: Congcong Peng (Silicon Integrated Co., Ltd.), Yun Shi (Silicon Integrated Co., Ltd.), Bixiang Yan (Guang Dong OPPO Mobile Telecommunications Corp., Ltd.), Lianjun Wu (Shenzhen Realme Mobile Communication Co., Ltd.), Zhipeng Chen (Silicon Integrated Co., Ltd.), César Salvador (Silicon Integrated Co., Ltd.) and Deheng Liu (Silicon Integrated Co., Ltd.)