Phillips was placed on the injured list on Sept. 17 after breaking his forearm in a loss to the Detroit Lions.
Phillips has missed the required eight games and could play as soon as Monday night in Mexico City against the Kansas City Chiefs. Phillips will have a 21-day window to practice with the team before needing to be added to the active roster.
Phillips is the first of two return candidates to be designated to return by the Chargers. Fellow safety Derwin James would likely be the second when he becomes healthy enough to return from offseason foot surgery.
Phillips played in all 16 games last season for the Chargers. He made seven starts with 94 tackles, nine passes defended, an interception and a forced fumble. Phillips is in his sixth season with the Chargers and has appeared in 59 career games for the team.