The phrase "announced a pledge of" is correct and usable in written English.
It can be used when someone is making a formal commitment or promise, often in a public or official context.
Example: "The organization announced a pledge of support for local charities during the annual meeting."
Alternatives: "declared a commitment to" or "made a promise of".
Japan, the host of the conference, announced a pledge of $5 billion over five years.
Intel has announced a pledge of $300m£198m8m) to encourage greater diversity in the technology sector.
He recently announced a pledge of a hundred million dollars to the museum's endowment fund — the largest monetary gift in moma's history.
The Norwegian government has announced a pledge of 145m kroner (£12m) to help fight forest crime such as illegal tree clearances.
Humanitarian aid: In January 2014 the US announced a pledge of $380m in humanitarian assistance for those inside Syria as well as for refugees in neighboring countries, bringing the total amount of humanitarian aid committed to the conflict, since it began, to more than $1.7bn.
Norway has announced a pledge of about $4.5 million, while Australia is adding $3.5 million in addition to the $32 million it gave in 2008.
They were among a group of Dallas collectors who in 2005 announced a pledge to donate their modern and contemporary collections to the Dallas Museum upon their deaths.
The Japanese prime minister, Shinzo Abe, was expected to announce a pledge of up to $1.5bn to the fund at the Brisbane summit, press reports said.
So we are announcing a pledge of £1bn to the Global Fund under full replenishment of $15bn … We can't do it all on our own, but if we all pitch together then we have a really good chance to put ourselves in shooting distance of some incredible results on HIV, TB and malaria".
Mayors of 32 of the nation's cities, including Mayors Bill DeBlasio of New York, Rahm Emanual of Chicago, Michael Nutter of Philadelphia, and Annise Parker of Houston, announced a pledge signed by 36 mayors that commits them to addressing the issues of early childhood education, income inequality, and equal access to the Internet in their cities.
