Combination method of DC-DC converter and LDO to improve efficiency and load regulation

Presented is a new combination method of a DC-DC converter and a low dropout voltage regulator (LDO), where the DC-DC converter takes the output voltage of the LDO´s error amplifier as the feedback voltage. This new method can dynamically adjust the dropout voltage of the LDO according to load current so that efficiency is improved especially for driving small loads. Simultaneously, this method can dramatically improve load regulation by reducing the variation of the input voltage difference of the LDO´s error amplifier.