UPDATE 1-Infineon to sell wireline coms unit to U.S. investor

* Says to sell its wireline communications unit

* To sell business for 250 million euros

* Closing expected in autumn 2009

(Adds company comment, background)

FRANKFURT, July 7 (Reuters) - Struggling German chipmaker Infineon (IFXGn.DE) will sell its only profitable business, the wireline communication unit (WLC), to a U.S. investor for 250 million euros ($349.5 million) in a further step to stabilise its finances.

The sale to an affiliate of Golden Gate Capital is expected to close in autumn 2009 and will significantly improve Infineon's financial situation, the company said late on Tuesday.

WLC has been hit by a continued weak market environment and ongoing inventory corrections in the supply chain but had an operating profit of 3 million euros in the first six months of Infineon's fiscal year.

Infineon, floated in 2000, faces refinancing needs of around 770 million euros over the next year and has pledged to come up with a refinancing plan by the summer.

In the past two months, its situation eased somewhat.

In May, Infineon generated proceeds of 180 million euros with a convertible bond issue and in June, cost cuts and cash saving measures enabled it to slightly raise its outlook for fiscal third quarter sales growth and group results.

Infineon, which is due to report on its third quarter on July 29, posted sales of 747 million euros and a net loss from continuing operations of 258 million euros in the quarter ended March 31.

Europe's biggest automotive chip supplier will have four units left after the sale: Automotive, Wireless Solutions, Industrial & Multimarket and Chip Card & Security.

The chipmaker competes with privately owned Dutch NXP as well as Texas Instruments TXN.N and STMicroelectronics (STM.PA) (STM).

(Reporting by Nicola Leske; Editing by Phil Berlowitz)