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 that depends on the voice-coil materials. Other tests consider the rated noise power, a specification obtained by rigorous lifetime tests. This paper investigates the thermal limits when micro-speakers operate at their specified rated power. These power-based thermal limits are contrasted with values of Tmax specified in datasheets. The evidence found is used to recommend procedures to measure power-based thermal limits that avoid over-protection.

Authors: Peng, Congcong; Shi, Yun; Yan, Bixiang; Wu, Lianjun; Chen, Zhipeng; Salvador, César; Liu, Deheng
Affiliations: Silicon Integrated Co., Ltd.; Silicon Integrated Co., Ltd.; Guang Dong OPPO Mobile Telecommunications Corp., Ltd.; Shenzhen Realme Mobile Communication Co., Ltd.; Silicon Integrated Co., Ltd.; Silicon Integrated Co., Ltd.; Silicon Integrated Co., Ltd.(See document for exact affiliation information.)
AES Convention: 148 (May 2020) eBrief:594
Publication Date: May 28, 2020
Subject: Loudspeakers & Microphones

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