Bristol Palin has gone to court, demanding that Levi Johnston step up as a dad and pay her some of the money he's raked in from his naked media blitz.

Court documents were filed by Bristol's lawyer late Thursday afternoon in Alaska, demanding $1,750 a month in child support from Levi, retroactive to the birth of son Tripp on December 27, 2008.

According to the docs, obtained by TMZ, Bristol believes Levi has pulled in "in excess of $105,000 in 2009 through various media interviews and modeling related activities." The $105,000 figure is significant, because under Alaska law a non-custodial parent must pay 20% of income up to $105,000 a year -- which comes to $1,750 a month.

Bristol says in her sworn statement, "I have received limited and sporadic financial assistance from Levi." Bristol says Levi has forked over only $4,400 over the 13 months of Tripp's life -- $3,000 on September 9, 2009, $1,400 on December 19.

Bristol's request is for temporary support, pending a permanent child support order.

UPDATE: Levi Johnston's manager, Tank Jones, tells TMZ Levi has paid Bristol more than $10,000 since Tripp was born. Jones also says Levi does not make money off of every interview he does, though he did not say exactly how much Levi has made.