Patent ID: 6181579
Filing Date: 2001-01-30
Classification: H02M,Y02B

Abstract:
A DC--DC converter comprising a main switching element provided on a primary side of a transformer, the transformer having a primary coil and a secondary coil, a synchronous rectifier comprising a MOSFET having a drain source and gate and a drain-source path, the synchronous rectifier coupled to the secondary coil, the synchronous rectifier switching in synchronism with a switching operation of said main switching element, the synchronous rectifier being provided on a line connecting one terminal side of the secondary coil of said transformer with an output terminal of a circuit on a secondary side of said transformer, further comprising an input capacitor, the gate of the synchronous rectifier being coupled so as to have applied thereto a voltage corresponding to an output voltage of said secondary coil by said input capacitor, so that a voltage generated on the primary side by switching operation of said main switching element is transmitted to the secondary side to be rectified and smoothed to output a DC voltage, further comprising a charge accumulating capacitor and a first diode connected in a first series circuit between the gate and source of the synchronous rectifier with a forward direction of the first diode being connected between the gate and source of said synchronous rectifier, and further comprising a discharge element discharging said charge accumulating capacitor connected in parallel with said charge accumulating capacitor.