SLUAA04A june   2020  – may 2023 BQ25150 , BQ25155 , BQ25618 , BQ25619 , TS5A12301E , TS5A3157 , TS5A3159A , TS5A6542

 

  1.   1
  2.   High-Efficiency Charging for TWS Using a 2-Pin Interface
  3.   Trademarks
  4. 1 Introduction
  5. 2 System Overview
    1. 2.1 Charging Case
      1. 2.1.1 BQ25619
      2. 2.1.2 TLV62568P
      3. 2.1.3 TPS22910A
      4. 2.1.4 TS5A12301E
      5. 2.1.5 MCU
    2. 2.2 Earbuds
      1. 2.2.1 BQ25155
      2. 2.2.2 TPS22910A
      3. 2.2.3 TS5A12301E
      4. 2.2.4 BT/SOC
  6. 3 Charging Case Algorithm Implementation
    1. 3.1 Initialization and Main Code
    2. 3.2 UART Interrupt and Output Voltage Adjustment
  7. 4 Earbud Algorithm Implementation
    1. 4.1 Initialization and Main Code
    2. 4.2 Interrupt and Transmission
  8. 5 Test Procedure
  9. 6 Test Results
    1. 6.1 Dynamic Voltage Adjustment
    2. 6.2 BQ25619 with 4.6-V Output
    3. 6.3 Standard Boost with 5V Output
  10. 7 Summary
  11. 8 Schematics
  12. 9 PCB Layout
  13. 10Software
    1. 10.1 Charging Case main.c
    2. 10.2 Earbuds main.c
  14. 11Revision History

2.2.1 BQ25155

This device is a linear lithium Ion battery charger with a built in ADC. It allows for variable input voltage while charging. This feature enables the efficient charging scheme outlined in this report. The device has a built in ADC that monitors multiple pins including battery voltage (VBAT), battery temperature (TS), an external ADC channel (ADCIN). There is also three comparators that enable many different functions including an over-temperature battery discharge function covered in the application note here. The device also has an interrupt pin that can trigger an MCU interrupt on many different flags. This flag based interrupt system is used to enable the interrupt driven communication that is outlined in this paper. To maximize the shelf life of the earbuds, the BQ25155 shipmode has an ultra-low current consumption of 10 nA. Space-constrained applications benefit from the BQ25155's 12-mm2 solution size. For this application, the VINDPM feature of the BQ25155 was disabled to allow charging at low VIN.