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

2 Delivering over 100 W power with USB PD

USB PD is a new protocol that enables faster and more flexible power sources. The USB Implementers Forum developed USB PD concurrently with USB-C, which is the physical connection, and it is a subset of the new USB 3.1 standards.

Table 2-1 shows the development of the USB standard. With the development of USB PD and USB-C connectors, the power source is capable to supplying as much as 100 W of power [1].

Table 2-1 Development of the USB standard for fast charging.
USB Standard USB Port Output Voltage USB Port Current Limit USB Port Maximum Power output
USB 2.0 5 V 500 mA 2.5 W
USB 3.1 5 V 900 mA 4.5 W
USB BC1.2 5 V 1.5 A 7.5 W
USB BC1.2 with high-voltage downstream charging port (HVDCP) 5 V, 9 V, 12 V 1.5 A 18 W
USB PD 5 V, 9 V, 12 V, 20 V 5 A 100 W
USB PD with PPS Adjustable voltage from 3.3 V to 21 V in 20-mV step Adjustable current up to 5 A in 50-mA step 100 W

Unfortunately, the traditional regulated buck, boost or buck-boost integrated circuit cannot fully use 100 W of power because of the relatively low efficiency. The unregulated switched-capacitor converter becomes feasible in the system with the development of USB PPS[2]. The ultra-high efficiency of the switched-capacitor converter can take full advantage of the latest USB Type-C PD PPS standard.