He was cut by the Green Bay Packers on Wednesday.
Smith, 24, is an intriguing player for San Diego, which could use some help at inside linebacker. Smith, a third-year player, started the first six games of last season before tearing his ACL. There were reports last month that there is no guarantee he will be ready for the start of the 2013 season. The Packers cut him with the failed physical designation.
Smith played in every game as a rookie. Still, it is a worthwhile signing for the Chargers. He has ability, and he should regain his health at some point in the 2013 season, Smith could be a player to watch in San Diego.
Meanwhile, as expected, San Diego receiver Danario Alexander signed his restricted free-agent tender.