Mike RayfieldMike Rayfield ran mobile-chip development since 2005 at graphics-processor maker Nvidia. But the executive quietly left the company on August 24, according to Engadget.

Rayfield is reportedly joining another firm. Nvidia hasn’t announced the departure and hasn’t said who will replace Rayfield, who was the general manager of the mobile business unit that has produced three generations of Tegra mobile processors. The chips are the Santa Clara, Calif.-based company’s bridge from the PC graphics industry to mobile devices, which are seeing a much faster growth rate. Nvidia’s chips are better at running games and multimedia, and both are high-demand features in the most powerful smartphones and tablets.

Based on recent earnings, mobile has become critical to Nvidia’s future, and the company has had a significant number of design wins. But Apple uses its own chips in devices such as the iPhone and iPad, and that has limited Nvidia’s growth. Rayfield reported to Philip Carmack, who is the senior vice president of the mobile business, while Gary Hicok is the senior vice president of the Tegra mobile business in charge of partnerships.

[Update: Nvidia confirmed Rayfield’s departure]