A computational current sensor, that enhances traditional Kalman filter based current observer techniques, with transient tracking enhancements and an online parasitic parameter identification that enhances overall accuracy during steady state and transient events while guaranteeing convergence. During transient operation (e.g., a voltage droop), a main filter is bypassed with estimated values calculated from a charge balance principle to enhance accuracy while tracking transient current surges of the DC-DC converter. To address the issue of dependency on a precise model parameter information and further improve accuracy, an online identification algorithm is included to track the equivalent parasitic resistance at run-time.