A VPP generator for tolerant load current variation using a variable pumping frequency for mobile DRAM is presented in this paper. The proposed charge pump adopts a 4 stages digitally controlled oscillator, regardless of the amount of load current boost almost a prescribed time are satisfied. As a result, our charge pump generates 2.5V output voltage with 7μs ramp-up time at 25㎂-62.5㎂ load current variation.