A phase current estimator for a switching power converter includes analog circuitry for generating a phase current estimate error by comparing a phase current of the switching power converter to an analog representation of an estimate of the phase current. The phase current estimator further includes digital circuitry for revising the phase current estimate based on the phase current estimate error and a plurality of parameters associated with operation of the switching power converter. An estimator fault detection unit is provided for determining whether a difference between the phase current and estimate exceeds a threshold for indicating substandard phase current estimation.