Lithium battery application scheme of portable Bluetooth player
The design of spare power supply for portable Bluetooth player
With the development of modern society, the way of entertainment has begun to turn to the outdoor, and many entertainment facilities have begun to tend to the outdoor type. Portable Bluetooth player is one of the equipment products for outdoor entertainment. Due to its miniaturization, high quality and quantification of speaker effect, and the integration of the special functions of home electric player and Bluetooth transmission, it has become the first choice of outdoor entertainment equipment in modern society. Because of the requirement of portability, providing a safe, efficient, stable, light and sufficient backup power solution for the portable Bluetooth player has become an important guarantee for people to carry out outdoor entertainment for a long time. Due to its unique advantages, the battery backup of portable Bluetooth player has become the first choice of power supply solutions for outdoor entertainment devices.
1、 Design requirements for spare lithium battery of portable Bluetooth player:
The working current of the player is small, but the continuous working time of the battery is required to meet at least 8 hours of continuous operation of the equipment. The battery shall have the over temperature protection function, and the finished battery shall pass the UL2054 certification requirements, and the weight of the battery shall be controlled within 200g. For this reason, our company adopts imported Samsung cell, which has the advantages of high energy ratio, light weight, small volume, high cycle life, high safety, high voltage and good consistency. The lithium battery pack is designed to output over-current protection value of 15a, maximum continuous working current of 2.2A, and charging capacity of 2.2ah, fully meeting the power consumption time demand of the player. The specific design parameters are as follows:
1) Model design requirements of lithium battery pack: 18650-3s1p / 2.2ah/11.1v.
2) Circuit design requirements:
1. Single section overcharge protection voltage: 4.35 ± 0.25V
2. Single section overcharge recovery voltage: 4.15 ± 0.50v
3. Single section over discharge protection voltage: 2.40 ± 0.08v
4. Single overdischarge recovery voltage: 3.00 ± 0.10v
5. Overcurrent protection value of combined battery (10ms): 10 ~ 17A
6. Over temperature protection value of combined battery (recoverable): 70 ± 5 ℃
7. The finished battery has short circuit and reverse charging protection.
3) Design requirements for battery cycle life: 300-500 times (GB charging and discharging standard)
4) Design requirements for external dimensions of battery: refer to the dimensions of finished battery
2、 Design scheme of spare lithium battery for portable Bluetooth player:
1) Protection board (PCM): it is mainly a protection circuit designed for rechargeable lithium battery. Due to the chemical characteristics of lithium battery, it is necessary to provide intelligent power calculation, overcharge, overdischarge, short circuit, overcurrent and other protection functions to avoid combustion, explosion and other hazards.
2) Protection IC (Protection IC): the main protection function chip of the design scheme, which can monitor the overcharge, overdischarge, overcurrent, short circuit and other functions of the electric core on-line at any time, so as to make the electric core work in a safe, stable and efficient range.
3) Temperature switch: mainly designed for temperature protection function. When the temperature of the battery reaches 70 ± 5 ℃ due to other abnormal problems, the temperature switch acts to protect the temperature
4) 18650 lithium ion cell: 18650 / 2200mAh / 3.7V Li ion cell (Samsung).
5) MOSFET: MOSFET, which plays a switching role in the protection circuit. It will never increase or decrease the voltage at both ends of the load, so as to ensure the voltage stability.
6) Battery package: PCV shrink
7) Schematic diagram of standby lithium battery design for portable Bluetooth player:
