'Hard Knocks' -- Broken Leg Rookie Vows ... I'M COMING BACK

You saw the injury ... you saw the tears ... but Cincinnati Bengals lineman Larry Black tells TMZ he is DETERMINED to get back into the NFL after mangling his leg in a freak accident captured on "Hard Knocks."

Millions watched as Black's promising rookie campaign came to a heart wrenching end last week when he suffered a dislocated ankle and broken fibula during a routine practice drill.

The big man's tearful phone call to his parents to pick him up from the hospital was... gulp, tissue... was the most poignant scene in the gritty behind the scenes show's history.

"The outpouring of support has been crazy ... thousands of tweets and letters coming from all over the world."

Black says doctors estimate his recovery will take between 6 and 12 months ... but he's confident, the injury won't stop him from pursuing his NFL dreams.

"If for some reason I don’t make it back – I've got a degree in Sports Management from Indiana and I’ll try to get a job with either a college or pro team helping to work with the athletes."

"But honestly I’m not even thinking about that right now. I’m just focused on getting back as quickly as possible. I’ll definitely be back."

There's a silver lining for the big man, who was an undrafted free agent ... because the injury was sustained on the field, he'll still get paid for the season -- and will pull in a figure just north of $200k ... in addition to his medical care.

In the meantime, Black says he's still rooting hard for the orange and black -- telling us he expects nothing less than a Super Bowl season.