急急急啊,LM1117的最大输入电压,规格书上是这样写,但到底??

第一
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Maximum Input Voltage (VIN to GND)
LM1117-ADJ, LM1117-1.8,
LM1117-2.5, LM1117-3.3,
LM1117-5.0, LM1117I-ADJ,
LM1117I-3.3, LM1117I-5.0    20V

第二
Operating Ratings (Note 1)
Input Voltage (VIN to GND)
LM1117-ADJ, LM1117-1.8,
LM1117-2.5, LM1117-3.3,
LM1117-5.0, LM1117I-ADJ,
LM1117I-3.3, LM1117I-5.0     15V
LM1117-2.85                  10V
Junction Temperature Range (TJ)(Note 2)

最大输入电压是不是20V,但它又写工作电压是15V
我的输入电压是18V,这样是不是不能用啊?谢谢