Rob Gronkowski and his family are raging through New England -- hitting up 3 children's hospitals in less than 24 hours ... in a mission to give away a TON of cash!!

Rob -- along with his bro Dan and father Gordie -- decided today would be the day they distributed the $75,000 they raised by raffling off tickets to the Super Bowl.

The donation spree started off at Boston Children's Hospital -- where the Gronks played games with the kids and then presented a big, ol $25,000 check!!!

Dan tells TMZ Sports the family is en route to Barbara Bush Children's Hospital in Portland, Maine -- followed by Hasbro Children's Hospital in Rhode Island.

And yes, each hospital gets a big $25k check -- and some play time with the Gronks!