By Shashwat Chauhan

July 22 (Reuters) - A slump in the dollar has come to the rescue of some major multinational U.S. companies this earnings season, easing the sting from President Donald Trump's tariffs that have driven up costs and upended financial planning.

A weaker dollar enhances the value of foreign earnings of U.S. companies, while also making American exports more competitive.

Companies such as Levi Strauss LEVI.N, Netflix NFLX.O, Pepsi PEP.O and 3M MMM.N, which generate significant revenue from overseas sales, reported a boost to their April-June earnings or raised their annual forecasts due to the slump in the dollar.

The greenback has lost =USD about 10% this year, due to rapidly changing U.S. trade policy and worries about growth and ballooning government debt.

Last week, PepsiCo, which relies on international business for about 40% of its total net revenue, forecast a smaller annual profit drop helped by a weaker dollar.

The dollar weakness "can be another source of upside that helps solidify the narrative of a very solid earnings season," said Angelo Kourkafas, senior global investment strategist at Edward Jones.

"However, there is a limit to how much credit investors will give to companies that demonstrate a large upside surprise to estimates just driven by currency trends."

Based on two decades of data, every 1% depreciation in the dollar historically improves S&P 500 earnings per share growth by about 0.6 percentage points, according to LSEG data. Roughly 38% of S&P 500 revenue is derived from international markets.

Information technology .SPLRCT, consumer discretionary .SPLRCD, health care .SPXHC and industrial .SPLRCI companies have the highest international exposure.

"We originally expected over $100 million of headwinds from a strengthening dollar and the reverse has happened," medical equipment maker Edward Lifesciences EW.N CFO Scott Ullem said at a Jefferies conference on June 4.

TAILWIND NOT ENOUGH

Still, a forex tailwind isn't always enough to reassure investors, who are looking out for signs of real growth as skittish consumers curb spending.

Investors typically do not reward FX-driven sales beats the way they reward constant-currency beats, Goldman Sachs strategists said in a note.

"In many ways, investors should consider some of these things as transitory or one-time adjustments that are not sustainable," said Michael Arone, chief investment strategist at State Street Investment Management.

Netflix NFLX.O shares declined more than 4% on Friday as some investors were disappointed by a revenue forecast raise that was driven more by a weaker dollar than strong demand.

Here's a list of some the companies that noted a currency-related impact in their latest earnings:

(Reporting by Shashwat Chauhan in Bengaluru; Editing by Saumyadeb Chakrabarty)

((Shashwat.Chauhan@thomsonreuters.com;))