Battery-powered audio system designers seek to achieve two goals: extending playback time and reducing cost. Older, conventional Class-D amplifiers, while reliable, have been part of this challenge because they consume too much power for portable systems.
Digital-input Class-D amplifiers have delivered audio in television sets for a decade. The problem with amplifiers designed for TVs is that they are not designed to save power. They are designed to be 85% efficient at full power, which is typically around 24 V. Most portable systems and smart speakers operate at half that voltage, reducing operational efficiency to around 60%. This means that 40% of the voltage sent from the battery to the amplifier never makes a sound. Put another way, the amplifier wastes nearly 20% to 40% of the battery as heat.
If you have a line-powered smart speaker, an inefficient amplifier could significantly increase the ambient internal temperature, even when idle. Excessive heat can make cases warm to the touch, which could shorten the life of other components, leading to premature system failures and returned products – both of which can damage the manufacturer’s reputation with their customers.
The core issue of efficiently converting chemical energy stored in the battery to acoustic energy from the speakers centers on managing the voltage demand of the output signal. Fix that, and battery life improves. Many designers of battery-powered audio systems want multiple, affordable ways to better manage the energy demand from the amplifier. At TI, we’ve learned that no single approach addresses all battery-powered systems, so our new audio amplifiers have three different ways to reduce power consumption:
Figure 1: Class-H boost battery life comparison
Figure 2: Higher efficiency at low power levels and in standby mode
Figure 3: External Class-H hybrid-pro boost control
Battery-powered systems and smart speakers have unique power requirements, but both need better efficiency than what conventional Class-D amplifiers can provide. TI’s portfolio of digital-input amplifiers can help you improve playback time and control cost while maintaining premium sound.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.