The present disclosure is directed to a system and method for adjusting a conversion speed of an asynchronous SAR ADC based on a margin of time between when a conversion of a sample of an analog signal completes and a next sample of the analog signal is taken, referred to as a “conversion time margin.” The system and method reduce the conversion speed of an asynchronous SAR ADC when the conversion time margin permits to reduce the amount of power consumed and/or noise produced by the asynchronous SAR ADC.