Action Surge, second use is character level or class level?

@JeremyECrawford Hello I am new nice to meet you Action Surge second use is character lvl or class lvl?

— Juan José López (@juan_zarkonlyne) January 3, 2016

You get the 2nd use of Action Surge when you are a 17th-level fighter, as shown in the Fighter table (PH, 71). #DnD https://t.co/W8PZX5nDtK

— Jeremy Crawford (@JeremyECrawford) January 5, 2016