Embodiments disclosed herein may relate to applying verify or read pulses for phase change memory and switch devices. When a voltage of the DC power supply is lower than a voltage of the secondary battery, the DC power system adds an extra voltage to the voltage of the DC power supply to provide an input voltage to the secondary battery higher than the voltage of the secondary battery by using an electric power of the secondary battery, and the secondary battery is charged. The laser tracker also includes an optical system that includes a lens and is used to determine the orientation of the patterned target. The static loop is activated via the control signal to refresh the data in the circuit element. Control circuitry determines a mode of operation by monitoring cycles of operation and detecting a predetermined pattern of cycles in which inductor current becomes negative.