Synchronous rectifier flyback circuit for zero voltage switching
First Claim
1. In a flyback circuit including a pulse width modulation part generating the pulse width modulation signal;
- a switch performing the switching operation according to the pulse width modulation signal that is outputted from said pulse width modulation part;
a transformer inducing primary voltage to secondary side according to switching action of said switch; and
a synchronous rectifier rectifying secondary side output voltage of said transformer,said flyback circuit using said synchronous rectifier featuring that it comprises;
a synchronous rectifier driver that delays the gate drive signal that is outputted from said pulse width modulation part after which the driver compares it with reference voltage that is outputted from said pulse width modulation part and then the driver amplifies result value so as to supply it as the drive signal for said synchronous rectifier part;
a level change device that drives the gate of said synchronous rectifier, changing the level of gate drive signal that is outputted from said gate drive device; and
an insulating transformer that transmits the drive signal that is outputted from said synchronous rectifier driver, to said level change device side.
1 Assignment
0 Petitions
Accused Products
Abstract
The present invention relates a flyback circuit for zero voltage switching {ZVS} in continuous mode {CCM} and discontinuous mode {DCM}, which circuit minimized loss generated when electrifying parasitic diode of MOS transistor {MOSFET} that is secondary side switch of synchronous rectifier and which also enabled ZVS in whole range of discontinuous mode {DCM}. Particularly it contains a synchronous rectifier driver that delays the gate drive signal that is outputted from pulse width modulation part after which the driver compares it with reference voltage that is outputted from pulse width modulation part and then the driver amplifies result value so as to supply it as the drive signal for synchronous rectifier part, a level change device that drives the synchronous rectifier gate, changing the level of gate drive signal that is outputted from gate drive device, and an insulating transformer that transmits the drive signal that is outputted from synchronous rectifier driver, to the level change device side. Wherewith it inverts the output signal of the pulse width modulation part in driving the synchronous rectifier gate, resulting in minimization of loss occurred at time of electrification of parasitic diode of MOS transistor {MOSFET} that is secondary side switch so that it makes effect to enhance efficiency letting it perform zero voltage switching {ZVS} under fixed frequency condition in discontinuous mode {DCM}.
74 Citations
6 Claims
-
1. In a flyback circuit including a pulse width modulation part generating the pulse width modulation signal;
- a switch performing the switching operation according to the pulse width modulation signal that is outputted from said pulse width modulation part;
a transformer inducing primary voltage to secondary side according to switching action of said switch; and
a synchronous rectifier rectifying secondary side output voltage of said transformer,said flyback circuit using said synchronous rectifier featuring that it comprises;
a synchronous rectifier driver that delays the gate drive signal that is outputted from said pulse width modulation part after which the driver compares it with reference voltage that is outputted from said pulse width modulation part and then the driver amplifies result value so as to supply it as the drive signal for said synchronous rectifier part;
a level change device that drives the gate of said synchronous rectifier, changing the level of gate drive signal that is outputted from said gate drive device; and
an insulating transformer that transmits the drive signal that is outputted from said synchronous rectifier driver, to said level change device side. - View Dependent Claims (2, 3, 4, 5, 6)
- a switch performing the switching operation according to the pulse width modulation signal that is outputted from said pulse width modulation part;
Specification