Industry Articles Paving the way for the next generation audio codec for True Wireless Stereo (TWS) applications - PART 2 : Increasing play time By Hai YU, Clément MOULIN (Dolphin Design) In this second part of Paving the way for the next generation audio codec for True Wireless Stereo (TWS) applications whitepaper, energy efficiency will be discussed and several means to achieve extra-long playtime will be exposed. Figure 1 highlights the functions under discussion amongst the main functionalities embedded in earbuds. Fig.1: Functional blocks of a typical TWS earbud chip 1- About power consumption When thinking about TWS audio systems in daily use, there are several ways to enhance the customer experience and provide a hassle-free user interface integration. One of the critical issues TWS system designers are facing is playtime, because battery space is usually very limited in TWS earbuds. In a TWS system, the tiny battery constrains the power and energy available for the entire system, which comes at an extreme premium in TWS earbuds, where only the tiniest battery fits. For example, the Apple Airpod earbud has a 93 mW-hr battery, which is roughly only 1% of the battery capacity of an iPhone 7. Light and handy is the most important design goal of TWS headsets. Limited by the small space of the charging cradle and the headset, the battery capacity used in these two parts cannot be increased. The capacity of the charging cradle is generally less than 1000 mAh (commonly in the 200-700mAh range), and the capacity of the headset is smaller, mostly less than 100 mAh. Therefore, whether it is a charging cradle, an earbud or a headset, attention should be paid to the low-power design of the system to ensure that the TWS product has a longer battery lifetime.