Surgical generator for ultrasonic and electrosurgical devices

In accordance with various embodiments, methods to control electrical power provided to tissue via first and second electrodes may comprise providing a drive signal to the tissue via the first and second electrodes and modulating a power provided to the tissue via the drive signal based on a sensed tissue impedance according to a first power curve. The first power curve may define, for each of a plurality of potential sensed tissue impedances, a first corresponding power. The methods may also comprise monitoring a total energy provided to the tissue via the first and second electrodes. When the total energy reaches a first energy threshold, the methods may comprise determining whether an impedance of the tissue has reached a first impedance threshold. The methods may further comprise, conditioned upon the impedance of the tissue failing to reach the first impedance threshold, modulating the power provided to the tissue via the drive signal based on the sensed tissue impedance according to a second power curve. The second power curve may define, for each of the plurality of potential sensed tissue impedances, a second corresponding power.