Texas Instruments Inc. is getting a new head for its wireless division, one of the most important units at the Dallas-based chipmaker.

TI said Friday that Gilles Delfassy, 51, is retiring as senior vice president and chief of the company's wireless business.

Effective immediately, TI's board of directors has approved Greg Delagi, senior vice president for digital signal processing systems, as Mr. Delfassy's replacement.

In a brief interview after the changes were announced, Mr. Delagi, 43, said Mr. Delfassy will stick around for a little while to help with the transition.

"My predecessor has built an incredibly great business in wireless," Mr. Delagi said. "He's the guy who is credited with growing this business into one of the most successful in TI's history."

Mr. Delfassy was not available for comment.

Shares of TI gained 7 cents to close at $28.39.

Cody Acree, an analyst with Stifel Nicolaus, said he was surprised both by the announcement and by the fact that the stock didn't take a bigger hit.

"It was a surprise," he said. "Fifty-one is obviously very young. He has been there 28 years, so it's not like he hasn't put in his dues. But he's still very young to be stepping down."

But Mr. Acree said there are no signs that Mr. Delfassy's departure was prompted by a conflict with the company.

"Gilles is hard to replace," he said. "He has been not only respected, but obviously has done a very good job."

Mr. Delagi should be able to step in quickly, though, Mr. Acree said.

"I've known Greg for a lot of years, and he's already responsible for a large portion of TI," Mr. Acree said. "TI has lost an asset. But TI has lots of assets."

Mr. Delagi said his experience with the DSP segment prepared him to manage the wireless division.

"[In] my previous life, a lot of the technologies were shared between groups, so I've got a very good working knowledge of the technologies and the customers," he said.

Mr. Delagi does have some challenging market conditions to deal with.

"Wireless has its ebbs and flows as far as market demand, and TI has suffered recently somewhat from that, but that has nothing to do with their own internal execution," Mr. Acree said.

When the company announced its third-quarter earnings in October, president and chief executive Rich Templeton said that sales of wireless chips in the fourth quarter would probably be below traditional levels.

TI will report its fourth-quarter numbers on Monday.

E-mail vgodinez@dallasnews.com