Power supply device of switching mode

摘要

A power supply device of a switching mode comprises a transformer, a direct current power supply circuit connected at an output end thereof with a first end of a primary winding of the transformer, a switching element connected at a first end thereof with a second end of the primary winding of the transformer and at a second end thereof with a ground, a control circuit connected at an output end thereof with the control end of the switching element for providing the switching element with a driving signal, a direct current output circuit connected at an input end thereof with the output end of a secondary winding of said transformer, a leakage current detection circuit connected at an input end thereof with a secondary side ground end of the transformer and at an output end thereof with a primary side ground end of the transformer for forming a leakage current loop and transmitting a leakage current signal at such time when a leakage current takes place. The power supply device further comprises a leakage current protection circuit which is coupled with the detection circuit such that the protection circuit is separated from the detection circuit, and that the protection circuit is controlled by the leakage current signal, and further that the protection circuit is connected at an output end thereof with an input end of the control circuit, and further that the protection circuit cuts off the output voltage as soon as the detection circuit transmits the leakage current signal.