TWS Bluetooth headset charging box is a headphone accessory, but its role is very important, because the earphone box design is more refined, smaller size, resulting in low battery capacity, long-distance logistics, silent suspension, so ultra-low self-discharge is a Hard indicator. In addition, the high integration, security, and cost performance of the headphone box power chip are also important directions for engineers.
The TWS True Wireless Bluetooth Headset consists of two headsets that are not cabled, independent of each other, and a headset charging box that charges them. In today's technology, the charging method of the TWS true wireless Bluetooth headset is basically charged by the earphone charging box, on the one hand, because the small inside of the earphone cannot accommodate a larger battery, and on the other hand, more space of the charging socket and other components are occupied.
1. Power PCBA
The power supply PCBA inside the TWS earphone charging box has two main purposes. It is responsible for charging the internal battery of the charging box, and also needs to charge the internal battery boost output of the charging box to charge the earphone. In addition, it also protects against the built-in lithium battery overcharge, over discharge, short circuit, over current and other protection functions.
First, control the external power supply to charge the TWS headset battery case and charge the external charger into the lithium-ion battery. The external charger here is mainly a 5V charger, such as a common mobile phone adapter, the interface is Micro USB or USB-C, and then the buck is converted to the 4.2V voltage required for the lithium ion battery to charge, in addition to 4.3V or 4.35 V multiple specifications. The charging chip is divided into two types: linear and switch. Among them, the charging efficiency of the switch is high and the heat is low, which is the current mainstream charging method.
Secondly, the TWS headset battery box power supply PCBA also needs to supply power to the TWS Bluetooth headset. At this time, the lithium-ion battery is boosted to 5V, and then output to the earphone. The earphone charges the built-in battery through the internal charging circuit. In this way, when the TWS headset needs to be powered, it can be put back into the charging box to automatically replenish the battery.
The charging box boost chip is also divided into synchronous and non-synchronous. Among them, the synchronous architecture has high efficiency, low heat generation, and low asynchronous rectification efficiency, which is the same as the mobile power supply.
There are two main types of batteries commonly used in TWS Bluetooth headset charging boxes, polymer batteries and cylindrical batteries.
The most common ones are lithium-ion polymer batteries, which are also known in the industry as soft-pack batteries, which are used in the same way as on mobile phones. The common form is square, because the battery size can be flexibly customized, suitable for designing a compact, lightweight battery case.
In addition, the 18650 battery is also widely used in the charging box. This type of battery has a diameter of 18mm and a length of 65mm. It looks like a cylinder, so it is also called a cylindrical battery in the industry. The 18650 battery is a common standard in the industry and is suitable for mass production in large quantities, so it is widely used in many industries, including the famous Tesla electric car.
The 18650 battery has a single unit capacity from 2000mAh to 3500mAh. The optional capacity section is abundant. The TWS Bluetooth headset charging box can provide more battery life for the headset. However, its volume is relatively large, and it is slightly thicker for designing the TWS Bluetooth headset.
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