Lithium battery Bluetooth headset charging parameters

The Bluetooth headset charges the lithium battery circuit. The core of the Bluetooth headset is radio frequency and baseband processing. In order to adapt to the integration of functions and the refinement of planning, companies such as CSR and Broadcom integrate radio frequency and baseband processing functions. 6 mm. The power consumption management plan of the entire headset requires fewer peripheral components and higher integration, which meets the requirements of the Bluetooth chip for load response and noise suppression. Most Bluetooth headsets are powered by lithium batteries with voltages ranging from 2.7v to 4.2v. The battery capacity is 90 mA to 170 mA. In order to meet the needs of long-term calls and music playback, the battery capacity is gradually increasing. In addition, according to the Bluetooth chip of the ARM or DSP core, two power supplies (1.8v and 2.7v) separate the core and the I/O power supply. In short, the microphone also needs a clean bias voltage. In the picture, the 500mA synchronous DC/DC converter integrates p-channel and n-channel MOSFETs, and the switching frequency of 2MHz is selected, and the conversion power reaches more than 92%. High switching frequency and PWM/PFM active switching technology enable engineers to choose surface adapter inductors and ceramic capacitors as low as 2.2h to meet the ripple requirements of filters and Bluetooth chips. The integrated LDO in TC1303 can supply 300mA of output current with a voltage difference of only 137mV. In order to further reduce the impact of DC/DC switching noise on circuit planning, during chip planning, separate the LDO power supply ground from the DC/DC power supply ground to ensure that the LDO output can supply clean voltage for the I/O part and the microphone. The normal voltage indicator pin supplied by TC1303 can be connected to the I/O of the Bluetooth chip to monitor the power supply voltage. The normal voltage indicator pin can detect the DC/DC output voltage (TC1303A ($0.9200)) or the LDO output voltage (TC1303B ($0.9200)), and can even detect the two outputs separately, so that they can be powered in order to meet the power supply requirements of different Bluetooth chips. MCP73855 can be used to charge lithium batteries. The integrated MOSFET, current detection resistor and reverse blocking diode can supply up to 400mA of charging current, which can be set through an external resistor or directly through the I/O output. MCP73855 can actively end the pre-charging, constant current, and constant voltage charging control of the lithium battery, and output the charging status to the LED or Bluetooth chip. Through the appropriate peripheral circuit, the charging status indicator pin can drive the two-color LED to realize the separation of the charging process and the charging terminal. Figure 2 shows the circuit used by MCP73855 in the Bluetooth headset planning. This is a constant current and constant voltage lithium battery charging control board. In the picture, Q1, R1, W1, and TL431 constitute a fine adjustable voltage regulator circuit. Q2, W2, and R2 constitute an adjustable constant current circuit. Q3, R3, R4, R5 and LED are charging indication circuit. As the voltage of the rechargeable lithium battery gradually increases, the charging current gradually decreases. After the battery is fully charged, the voltage drop on R4 gradually decreases, which eventually stops Q3 and the LED drops. In order to ensure sufficient battery, please continue to charge for 1~2 hours after the indicator light goes out. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: Why is the battery life problem difficult to break?