A method for supplying bursts of substantially constant voltage to a switched load via a voltage reservoir. Based on a predetermined current that is to be sourced by the load during an active portion of a switching cycle, computing an average current that should be fed to the voltage reservoir during an inactive portion of the switching cycle to ensure that sufficient energy will stored in the voltage reservoir to supply the load without completely draining the voltage reservoir. Supplying continuous energy to the voltage reservoir at a substantially constant current equal in magnitude to said average current.