BATTERY CHARGER CIRCUIT WITH LOW STANDBY POWER DISSIPATION

摘要

A battery charger circuit is provided. One battery charger circuit in accordance with the present invention includes a switching element in series with a primary winding of a transformer. Control circuitry renders the switching element conductive during an on period so as to produce a current through the series arrangement and renders the switching element non-conductive during an off period. A method to reduce standby current in a battery charger circuit is also provided. One method in accordance with the present invention includes the steps of defining a current path in series with a first winding of a transformer, and sensing current flowing through the current path. The method also includes the steps of allowing the current to flow to the first winding when the current includes a load current and a magnetizing current, and preventing the current from flowing to the first winding when the current includes only a magnetizing current.