SLYY195A August   2020  – May 2022 BQ25790 , BQ25792 , BQ25798

 

  1.   At a glance
  2.   Authors
  3.   3
  4.   Why universal charging
  5.   On-the-go charging
  6.   Integrated components maximize power density
  7.   Implementing buck-boost charging
  8.   Conclusion
  9.   References

On-the-go charging

In order to support the USB On-the-Go (OTG) specification,one DC/DC converter discharges the battery to build up a regulated voltage at VBUS and power external devices when the adapter is not present. If the USB Type-C port requires fast role swap (FRS), the DC/DC converter has to be enabled and kept on standby all the time, even if an adapter is plugged into the USB Type-C port. When the adapter is disconnected, the back-to-back MOSFETs in the discharging power path turn on, passing the U3 output voltage to VBUS and holding on the VBUS voltage. Keeping the DC/DC converter always on actually causes extra quiescent current loss for the entire system.

GUID-20220426-SS0I-9JF9-5TZD-74TDRTX6VVVF-low.gif Figure 2 Example of a fully integrated buck-boost charger.