Patent ID: 6104623
Filing Date: 2000-08-15
Classification: H02M,Y02B

Abstract:
A DC--DC converter, comprising:a transformer having at least a primary winding, a secondary winding and a drive winding;an input circuit coupled to said primary winding of for coupling an input DC voltage to said transformer primary winding;a first output channel coupling said transformer secondary winding to a first output, said first output channel including a self driven synchronous rectifier circuit, a first inductor, and a first capacitor;a first pulse width modulator coupled between said first output channel and said input circuit to drive said input circuit, thereby regulating said first output channel;a second output channel coupling said transformer secondary winding to a second output, said second output channel including a control switch, a freewheeling rectifier, a second inductor, and a second capacitor;a second pulse width modulator coupled between said second output channel and said control switch for controlling a conduction interval of said control switch to thereby regulate said second output channel independent of said first output channel;an enabling switch, controlled by said second pulse width modulator and coupled between said transformer drive winding and a control terminal of said control switch, wherein said enabling switch modifies a voltage of said transformer drive winding to control the conductivity state of said control switch; anda drive rectifier, coupled between said transformer drive winding and a control terminal of said freewheeling rectifier, and a discharge switch coupled to said control terminal of said freewheeling rectifier, wherein said discharge switch is controlled by said second pulse width modulator to control the conductivity state of said freewheeling rectifier.