Two questions：
1.BQT24157：When charging is disconnected, whether the output of VBUS will drop instantly
2.Seeking a charging management chip:
1）The battery can be powered by an external 5V input;
2）Regardless of whether the external input power supply ，It has a stable 5V output (current about 1A), there will be no short-term power-down phenomenon in the power path switching;
3） This 5V output can control the output by pressing the button short/long press.
