A current-sharing multiphase sliding-mode switching power supply (24) and method of operation are presented. A bipolar power source (22) is coupled to a switch (30) for each phase (28), each switch (30) is in turn coupled to an inductance (32), and a capacitance (36) is coupled to the inductances (32) and across a load (26). A sliding-surface generator (78) generates a sliding surface (.sigma.). A current-balance control (80) computes a reference current as a summary statistic (I.sub.X) of inductive currents (I.sub.L) through the inductances (32), calculates an error current (I.sub.E) for each phase (28) as a difference between the summary statistic (I.sub.X) and the inductive current (I.sub.L), and adjusts the sliding surface (.sigma.) for each phase (28) so that all inductive currents (I.sub.L) are substantially equal to the summary statistic (I.sub.X). A switching circuit (138) switches the switches (30) in response to the sliding surface (.sigma.).