Systems and methods for powering up circuits are described herein. In one embodiment, a method for power up comprises comparing a voltage of a first supply rail with a voltage of a second supply rail, and determining whether the voltage of the first supply rail is within a predetermined amount of the voltage of the second supply rail for at least a predetermined period of time based on the comparison. The method also comprises initiating switching of a plurality of switches coupled between the first and second supply rails upon a determination that the voltage of the first supply rail is within the predetermined amount of the voltage of the second supply rail for at least the predetermined period of time.