BQ3287MT-SB2 Is a Clock/Calendar IC that has been discontinued by Texas Instruments. It is still available through Rochester Electronics, but long lead times may present an issue for customers. Here are some alternatives that should work in its place for most applications:
At time of writing, these options are active and in stock. The first two items are a better match for the original footprint, but each of these is viable in terms of overall specifications. Please review the datasheets to ensure the alternative will work for your application.