再看看下面关于LDO3的解释
3.3V Linear-Regulator Output. LDO3 powers up after REF is in regulation. LDO3 can provide a
total of 100mA to external loads. If OUT3 is greater than the LDO3 bootstrap-switch threshold,
the LDO3 regulator shuts down and the LDO3 pin connects to OUT3 through a 1.5Ω switch.
Bypass LDO3 with a minimum of 4.7µF. Use an additional 1µF per 5mA of load.