Driving circuit of synchronous rectifier

Abstract

The embodiment of the invention discloses a driving circuit of a synchronous rectifier. The driving circuit comprises a controllable clamping circuit. The first end of the controllable clamping circuit is coupled to the first end of the synchronous rectifier, the second end of the controllable clamping circuit is coupled to the second end of the synchronous rectifier, the third end of the controllable clamping circuit is coupled to the control end of the synchronous rectifier, and the control end of the controllable clamping circuit is used for receiving the potential indication signal from the power supply end of the driving circuit. When the potential indication signal indicates that the potential of the power supply terminal of the driving circuit is not established, the controllable clamping circuit connects the third end of the controllable clamping circuit with the second end of the controllable clamping circuit based on the potential of the first end of the controllable clampingcircuit, thereby keeping the synchronous rectifier off and preventing mistaken conduction caused by coupling the noise signal to the control end of the synchronous rectifier.

Description

technical field [0001] Embodiments of the present disclosure relate to an electronic circuit, in particular to a driving circuit for a synchronous rectification device. Background technique [0002] Synchronous rectification devices can be used in various applications, such as secondary switching devices for isolated converters such as resonant converters and flyback converters. When the isolation converter just starts / starts to work, when the primary side switching device is turned on to form a current path on the primary side, the voltage at both ends of the synchronous rectification device will increase due to mutual inductance on the secondary side (for example, the synchronous rectification device is MOSFET, the voltage across its drain-source increases). At this time, since the drive circuit controlling the synchronous rectification device has not yet established the required drive level, the pull-down impedance of the control terminal of the synchronous rectification...

AI Technical Summary

Problems solved by technology

At this time, since the drive circuit controlling the synchronous rectification device has not yet established the required drive level, the pull-down impedance of the control terminal of the synchronous rectification device (for example, when the synchronous rectification device is a MOSFET, the pull-down impedance of its gate) Very large (for example, it can reach the mega-ohm level), so the noise signal is easily coupled to the control terminal of the synchronous rectification device and causes the synchronous rectification device to turn on

Once this happens, since the primary switching device and the synchronous rectification device are turned on at the same time, it will not only cause the isolation converter to fail to start, but even cause unexpected consequences such as damage to circuit components.

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