* Siemens says to float "significant" minority stake
(Adds details in timing, debt):
FRANKFURT, Feb 19 (Reuters) - German engineering group Siemens on Monday announced plans to float its medical imaging and diagnostics business Healthineers on the Frankfurt stock exchange, putting it on track for a listing in late March. Siemens said the initial public offering (IPO) was due some time in first half of 2018, but the so-called “intention to float” statement typically sets up companies to go public about four weeks later.