A current mode buck DC-DC converter with using a load adaptive method (LAM) to keep high efficiency within wide load current range are presented in this paper.The converter used error signal and a load adaptive threshold to flexible switch in pulse width modulation (PWM) mode and skip mode according to the load current.In skip mode

the converter can reduce switching loss and quiescent consumption.Through analysis and derivation

the relations between load adaptive threshold

inductance peak current and load current were inferred.Simulation results implemented in 0.5m BCD process shows that

under the condition of 12 Vinput and 3.3Voutput

When the load is light

the converter enters LAM mode

the efficiency is much higher than the same load in PWM mode

especially in =10mA

the efficiency of PWM mode is only 45.6%

but in LAM mode the efficiency reach 80.1%.