Chris Brown -- Baby Mama Claims Deadbeat Dad ... He Says She's Money Hungry

Chris Brown is at war with his baby mama, who claims he's stopped paying the measly $2,500 a month in child support, and now she's gunning for 6 times that.

Multiple sources connected with the couple tell TMZ, Chris has been paying baby Royalty's mom, Nia Guzman, the $2,500, but the gravy train stopped in March. Our Chris sources say he stopped paying because Nia demanded $15k a month, which he thinks is ridiculous.

We're told Chris says Nia's treating the baby like a winning lottery ticket, but she claims he's being incredibly cheap and their daughter is suffering as a result.

We're told Nia's lawyer, Carl Moore, will be filing legal docs in the next 2 weeks demanding back child support and a huge monthly hike.