* Samsung to report Q1 operating profit, sales estimates
* Profit seen at 5 trln won; up 70 pct from yr-ago
* Most bullish view is for record 5.6 trln won profit
* Shares up 25 pct this year to record highs
By Miyoung Kim
SEOUL, April 6 (Reuters) - Samsung Electronics, the world's top technology firm by revenue, will report strong first-quarter profit of around $4.5 billion on Friday on soaring sales of its flagship Galaxy smartphones and the new Note, a mini-tablet and phone.
Samsung, which raced to the top of the global smartphone rankings last year with close to a fifth of the market, from just 3 percent in 2009, should consolidate its position with more product launches, including a revamped Galaxy S, over the next few months.
Samsung, Asia's most valuable technology firm worth some $190 billion, reports its January-March guidance ahead of detailed quarterly results due on April 27.
January-March operating profit is seen at around 5 trillion won ($4.4 billion), up 70 percent from a year ago, but down 6 percent from the preceding quarter's record 5.3 trillion won, according to a consensus of 34 analysts surveyed by Thomson Reuters I/B/E/S.
Revenue is forecast at 45.5 trillion won.
"We hugely underestimated Samsung's smartphone performance in the first quarter," said CLSA analyst Matt Evans, increasing his profit forecast by 56 percent to 5.6 trillion won, the most bullish market view.
"Our view that margins wouldn't significantly increase was very wrong ... This strong performance has been driven by not just higher than expected volumes but also increased dominance at the high-end of the Android market, where there was little new competition ... Samsung's smartphone shipments probably exceeded Apple's by a significant margin."
Samsung's shipments are forecast at a record 44 million smartphones in the first quarter just ended, up by nearly 25 percent from October-December levels, according to a Reuters survey of analysts.
Analysts have been raising their Samsung profit estimates in recent weeks to reflect the strong handset sales - 28 of 35 estimates have been revised in the past 30 days, pushing up the average estimate by 13 percent, according to Thomson Reuters StarMine.
Samsung introduced the Galaxy Note, a mini-tablet and phone with a screen half the size of the iPad, in late October, and the top-end model has quickly become its core profit earner.
Sales of the Note, which has revived the throwback stylus function, have topped 5 million, increasing the competition against Apple Inc and smartphone strugglers HTC , Nokia and Research in Motion.
"Both smartphone shipments and profit growth are likely to be much stronger than consensus. Sales of the Note were very good and it's become Samsung's fresh money generator," said Lee Seung-woo, an analyst at Shinyoung Securities, adding earnings from just the Note and the Galaxy S could have topped 2 trillion won.
The handset division is likely to account for around two thirds of Samsung's total profits, analysts forecast.
While Apple is Samsung's biggest rival in smartphones, the U.S. company is also its biggest client, gobbling up Samsung's high-end displays and microchips for its iPhone and iPad.
"Samsung's integrated business model - for instance, it makes its own application processors and AMOLED screens - is the biggest ingredient of its winning formula, which, in our view, can't be easily copied," Daniel Kim, an analyst at Macquarie, wrote in a research note.
Song Myung-sup, an analyst at HI Investment & Securities, forecast Samsung's smartphone market share gains would accelerate with the release, probably in June, of the next version of the Galaxy S. "Its smartphone growth momentum will continue at least until the end of the third quarter," he said.
Earnings prospects for memory chips, where Samsung is also a world leader, have also brightened since Japan's Elpida Memory filed for bankruptcy, prompting its customers to switch to rivals such as Samsung and SK hynix to secure supplies of the chips used in smartphones and laptops.
"Contract chip prices are likely to continue to rise in the second quarter, possibly another 10-15 percent, as big customers like Apple, Dell and HP may seek to increase supply in the wake of Elpida's trouble," said Choi Sung-jae, an analyst at SK Securities.
Samsung shares have risen by a quarter so far this year, and hit a life high of 1.351 million won ($1,200) on Wednesday. Over the same period shares in Apple have soared by more than half, taking the California-based firm's value to above $582 billion - more than three times that of Samsung.