Aldon Smith -- Welcome to the Raiders ... You've Been Charged with DUI, Hit & Run

Ex 49ers star Aldon Smith got a new team Friday ... signing with the Oakland Raiders -- but he also got charged with DUI, hit & run, and vandalism. A real good news/bad news kinda day.

As we previously reported ... Smith was busted last month after allegedly smashing his car into his neighbor's parked car. Aldon fled according to cops ... only to return, where he was arrested for DUI.

Talk about coincidence -- the Santa Clara D.A. decided to charge Smith today, and the D.A.'s Office tells us ... he's facing up to 2 1/2 years in county jail, if convicted.