本帖最后由 鱼儿飞 于 2019-6-14 15:39 编辑

从丝印看，你用的是AMS1117，而且是JLC SMT的，证明确实是AMS产的1117，根据数据手册规定：
Stability
The circuit design used in the AMS1117 series requires the use of
an output capacitor as part of the device frequency compensation.
The addition of 22uF solid tantalum on the output will ensure
stability for all operating conditions.
When the adjustment terminal is bypassed with a capacitor to
improve the ripple rejection, the requirement for an output
capacitor increases. The value of 22uF tantalum covers all cases
of bypassing the adjustment terminal. Without bypassing the
adjustment terminal smaller capacitors can be used with equally
good results.
To ensure good transient response with heavy load current
changes capacitor values on the order of 100uF are used in the
output of many regulators. To further improve stability and
transient response of these devices larger values of output
capacitor can be used.
要用ESR较大的电解电容才能够使LDO环路稳定。