How can an outdoor Bluetooth speaker output the same power as a 12V lead-acid battery using two 7.4V lithium batteries?

Lead-acid batteries have always been the main power supply for high-power outdoor speakers. Lead-acid batteries have high voltage and high output current, and can directly supply audio amplifiers with 2×20W power. However, lead-acid battery power supply also has its disadvantages: large size, not environmentally friendly, and low number of cycle charging. With the technological advancement of lithium batteries, advantages such as light weight, small size, high number of cycle charging, and green environmental protection have been widely used. Considering the portable and mobile characteristics of outdoor Bluetooth speakers, based on factors such as volume, weight, service life, and environmental protection, two-series 7.4V lithium batteries are the ideal power supply for outdoor Bluetooth speakers in the future (3-series lithium batteries have to consider balance and charging costs due to differences between batteries, which limits their application). However, the voltage of two 18650 lithium batteries in series is 6V-8.4V. In the case of direct battery supply, each channel can only provide a power output of 7W/4 ohms, and the volume is relatively low.

Shenzhen Yongfukang Technology Co., Ltd. has summarized the pain points of market applications and is now vigorously promoting a two-cell lithium battery 7.4V power supply with built-in boost dual-channel D-class amplifier IC-CS85711, which can be widely used in mid-to-high-end square dance speakers, smart speakers, portable Bluetooth speakers and other product fields. At the same time, it is equipped with a 5V input boost switch type two-stage lithium battery charging management chip CS5090, which can save the adapter. Its high efficiency, high power, simple peripherals and other characteristics have accelerated the realization of lithium batteries replacing lead-acid batteries in the field of pull-bar speakers and other fields to become the mainstream power supply method.

The CS83711 is powered by a 7.4V lithium battery and has a built-in boost voltage of 11.05V, which can provide a peak output power of 2×20W/3 ohms. In addition, the overall efficiency of the CS83711 is as high as 90%, ensuring constant output power, the required playback time of the whole machine, and the temperature rise is within the normal range. Another highlight of the CS83711 is that it can support direct external 12V power supply, which is convenient for the whole machine to reserve an external 12V power cord clip interface. The CS83711 also has other rich functions and performances: two optional anti-breaking sound, spread spectrum mode, overcurrent protection, short circuit protection, overheating protection, etc.; the simple EQA-28 package is also very convenient to produce.

CS83711 Application Features

1. The 7.4V power supply of CS83711 is compared with the 12V direct output power of ordinary audio amplifiers. The actual measured power of CS83711 is 2×20W.

2. CS83711 whole machine efficiency test, the actual measured efficiency is over 90%.

3. CS83711 pinout

4. CS83711 Pin Description

5. Schematic diagram of 2×20W Bluetooth outdoor speaker solution based on CS83711 two-cell lithium battery with built-in boost

6. CS83711 power amplifier schematic

7. 2×20W Bluetooth outdoor speaker solution based on CS83711 two-cell lithium battery built-in boost PCB top-level design diagram DEMO

8. 2×20W Bluetooth outdoor speaker solution based on CS83711 two-cell lithium battery built-in boost PCB bottom design diagram DEMO

9. Based on CS83711 two-cell lithium battery built-in boost 2×20W Bluetooth outdoor speaker solution DEMO patch diagram

10. Based on CS83711 two-cell lithium battery built-in boost 2×20W Bluetooth outdoor speaker solution DEMO board actual picture

11. Overall board DEMO BOM table