Patent ID: 6912136

Claim:
A switching power supply comprising: a power transformer having a primary and a secondary; a switching element for coupling a voltage source to the primary; a current sensor that measures a primary current and a secondary current; a rectifier coupled to the secondary adapted to conduct current to a load coupled thereto; and a control circuit coupled to the current sensor and the switching element that controls the operation of the switching element in response to the primary current and the secondary current; wherein when the primary current in the primary reaches a first threshold, the control circuit causes the switching element to disconnect the voltage source from the primary which stops flow of the primary current in the primary and which causes the secondary current to conduct to the load; and wherein when the secondary current drops to a second threshold, the control circuit causes the switching element to reconnect the voltage source to the primary which terminates the secondary current flow in the secondary and which causes the primary current to flow in the primary.