Current sensing is one of the most important functions on a smart power chip. Conventional currentsensing methods insert a resistor in the path of the current to be sensed. This method incurs significant power losses, especially when the current to he sensed is high. Lossless currentsensing methods address this issue by sensing the current without dissipating the power that passive resistors do. Six available lossless current sensing techniques are reviewed. A new scheme for increasing the accuracy of current sensing when the discrete elements are not hown is introduced. The new scheme measures the inductor value during IheDC-DC controller startup.