为什么bq76940的CHG要用到一个PMOS,DSG为何不要用，请问一下是何作用？谢谢！
Q3 is a low-cost PCH FET and is used to keep CHG away
from any voltages below VSS. When CHG is not being
pulled high, PACK– being pulled below VSS will not be
seen by CHG as Q2 does not turn on. Q3 also allows R2to
keep Q1 OFF, since all voltages below this FET can
“follow” PACK– as it goes below VSS.
