SLYT819 October   2021 BQ25980

 

  1. 1 Introduction
  2. 2 Delivering over 100 W power with USB PD
  3. 3 High-efficiency switched-capacitor DC/DC converters
  4. 4 Output impedance
  5. 5 Switching losses
    1. 5.1 Turnon switching loss
    2. 5.2 Turnoff switching loss
    3. 5.3 Gate driving loss
  6. 6 Dual-phase interleaved switched-capacitor converter
  7. 7 High-power-density switched-capacitor converter
  8. 8 Switched-capacitor converter application: fast charging for portable devices
  9. 9 Conclusion
  10. 10Related Websites
  11. 11Important Notice

8 Switched-capacitor converter application: fast charging for portable devices

One of the applications for a switched-capacitor converter is a battery charger for portable devices. The customizable capability of the USB PPS allows the unregulated switched-capacitor converter to charge the battery at a 50% fixed-duty cycle. The power loss in portable devices is limited by the thermal profile; sometimes the temperature rise is limited to as low as 10˚C. Battery chargers need to have a small footprint. The high efficiency and high power density of switched-capacitor converters could push the charging power much higher compared with the inductor-based regulated converter.

The BQ25980 [10] is a switched capacitor-based two-cell battery fast charger that can help achieve more than 98% efficiency between 2 A and 8 A, as shown in Figure 8-1. Placing two of the BQ25980 devices in parallel achieves the 120 W power together with 2.4 W/mm3. The battery charges from 0% to 100% within 15 minutes [11].

Figure 8-1 BQ25980 switched-capacitor converter efficiency.