Building a DIY launch control?
Just googled that part number and found this listing with a link to a Chinese supplier:
LM2617N - Search & Buy LM2617N from Specialized Suppliers, Distributors & Manufacturers
NTE has a cross-reference that may help here:
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf
That part references as NTE995... ton of US distributors listed here:
Search Results | NTE-Electronic Components Supplier
Locally, you could try Active Components, Pacific Semiconductor, or maybe Main Electronics.