Part of Millennium Partners’ affordable housing obligation from construction of its $1.3 billion Winthrop Square skyscraper in Boston’s Financial District, now called the Winthrop Center, will support development of a 152-unit apartment and condominium tower in Chinatown.

The Boston Planning and Development Agency last week approved the tentative designation of its 0.7-acre parcel 12 at 280 Tremont St. as the site of a multifamily development by Millennium Partners and the Asian Community Development Corp.

The proposed 339,000-square-foot tower would contain 45 apartments for households earning 30 to 60 percent of the area median income, and 107 condos for households earning 60 to 100 percent of AMI.

Building designs will enable the Tufts Shared Services garage to add 264 spaces, and the abutting Doubletree Hotel to add 140 rooms and a conference center fronting on Tremont Street.

Millennium Partners also agreed to pay $5 million to support affordable housing elsewhere in the city.

Boston’s inclusionary development policy requires multifamily developers to pay a “cash-out” fee of up to $380,000 per unit if they don’t set aside 13 percent of the housing units on-site as income-restricted.

Millennium broke ground in October on the Winthrop Center office and luxury condo tower at 115 Federal St.

Developers have 270 days to provide the BPDA with a proposed development schedule and information on their debt and equity financing for the Tremont Street site.