(Adds outlook, share decline, details)
FRANKFURT, July 30 (Reuters) - Germany's Dialog Semiconductor posted a 44 jump in quarterly revenue on Thursday on surging demand for its chips from phone makers Apple and Samsung, but disappointed investors with its sales outlook.
The chipmaker reported second-quarter revenue of $316.5 million and said it expected third-quarter revenue to be in the range of $325 million to $355 million, below an average forecast of $356 million in a Reuters poll for the period.
That unnerved investors as the company had said in May that revenue would be strongest in the second half of the year.
The company's shares slumped 7.8 percent in Frankfurt trading by 1000 GMT. Despite Thursday's decline, the stock was still a third higher than at the start of this year.
Growth expectations have been riding high for Dialog, a key supplier of power management chips to Apple ahead of the technology giant's expected launch in late September of updated iPhones and a new, larger-screen iPad tablet.
"Given our current visibility, we expect 2015 to be another year of good growth driven by a solid ramp of high volume new products. Revenue performance will be weighted towards the second half of the year," the company said in a statement.
Second-quarter revenue from its mobile systems business - which generates roughly four-fifths of sales - grew 56 percent, but the company had slower growth for its wireless chips used in music and game accessories and car and industrial controls.
However, operating earnings, excluding special items, rose to $71.2 million, beating even the most optimistic estimate of $66 million in a Reuters poll, which had an average estimate of $58.2 million.
Dialog also said its finance chief, Jean-Michel Richard, planned to step down later this year after nine years at the company and that a search for his successor was underway. (Reporting by Eric Auchard and Harro ten Wolde; Editing by Susan Fenton)