The oscillation described in the previous slide continues indefinitely—at approximately 3 MHz, but deviates as necessary to respond to transient line and load changes—maintaining the output voltage at the programmed value and the average inductor current at the value required by the output load. This approach is relatively new. Previously, the principal approach to DC-to-DC conversion has been a constant-frequency peak-current approach, also known as trailing-edge modulation when implemented in step-down dc-to-dc converters.