Preface

Since iPhone7 canceled the 3.5mm jack，the bluebooth headset market has developed rapidly，the birth of Apple Airpods also brought a new technological change to the bluebooth headset market：TWS（True Wireless Stereo）.
TWS ture wireless bluetooth headset consists of two independent headsets without cables and a headset charging box for charging them.Compared with the ordinary bluetooth headsets, TWS true wireless bluetooth headsets have the following advantages：
1.True wireless structure, completely abandon wired troubles,and move more freely；
2.It can be used in a variety of ways, both for exclusive use and sharing, and one machine can be used as two machines.

 

Both the charging box and the two independent headsets need to use a lithium battery charging chip，especially the charging chip in the headset has high requirements for the accuracy of the charging current. In this regard, our company has developed a linear lithium battery charging chip ET9562 suitable for smart wearable devices.
 

ET9562 Introduction

ET9562 is a linear lithium battery charging chip with power path management. The charger uses constant current/constant voltage mode to charge the lithium battery. The maximum withstand voltage of the input can reach 24V，at the same time, when the input voltage is higher than 6V, the circuit will enter the overvoltage protection state and stop charging. In the charging mode, the charger has the functions of trickle charging,constant

current charging, constant voltage charging, charging cut-off and charging status display.

Built-in power path management system, which can balance the power supply to the system and the battery. At yhe same time, ET9562 integrates dynamic power management system，when the system load is too high，in order to ensure the stability of the input current and voltage, the charging current will be automatically reduced.

ET9562 provides overcurrent protection from input to system and battery to system, thus avoiding damage to lithium battery caused by excessive current. At the same time, when the battery enters the low-voltage protection state, the battery power supply to the system will be shutdown. ET9562 can set some key parameters through the I2C interface，such as battery constant-voltage charging, constant-current charging current, trickle charging threshold voltage, battery low-voltage protection threshold voltage,input limit current, input limit voltage, system power supply voltage and other parameters.

ET9562 Power Path Management Structure

ET9562 Typical  Application  Circuit

ET9562 Measured Charging Process Curve

ET9562 Features

（1）V_IN  Max Withstand Voltage：24V

（2）Built In 6V Overvoltage Protection

（3）Automatic Power Path Management

（4）Charging Voltage Accuracy:±0.5（5）Set Parameters Through I2C Interface

（6）Provide External Thermal Protection Through The NTC Port

（7）Use WCSP-9 Package