Combined switch and synchronous rectification circuit

Abstract

The invention discloses a combined switch comprising a first transistor, a second transistor, a first body diode, a second body diode and a first diode, wherein the cathode of the first body diode is connected with the drain of the first transistor, and the anode of the first body diode is connected with the source of the first transistor; and the cathode of the second body diode is connected with the drain of the second transistor, and the anode of the second body diode is connected with the source of the second transistor. The combined switch further comprises a first transistor and a second transistor both of which are reversely connected in series, wherein the first diode is parallelly connected with the first transistor and the second transistor which are connected in series. The combined switch can be used for solving the problems that a diode has large conduction loss during normal rectification, or the reverse recovery losses of body diodes are large by utilizing an MOSFET (metal oxide semiconductor field effect transistor) and the body diodes during synchronous rectification and the like, and improving the efficiency of a circuit.

Description

technical field [0001] The invention relates to the field of power supplies, in particular to a combination switch and a synchronous rectification circuit. Background technique [0002] With the introduction of the concept of green energy, people's awareness of environmental protection and energy saving is getting stronger and stronger, and all fields are trying to reduce losses and improve efficiency, and the power supply field is no exception. Nowadays, the requirements for power supply efficiency are getting higher and higher, and the conduction loss of the rectifier diode and the loss caused by reverse recovery account for a large proportion of the loss of the power supply. For a long time, a large number of engineers have invested a lot of energy, using various methods to reduce the loss of rectifier diodes, and are committed to optimizing the working performance of rectifier diodes. [0003] figure 1 Shown is an ordinary bridgeless power factor correction (Power Fact...

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Problems solved by technology

[0005] In view of this, the technical problem to be solved by the present invention is to provide a combined switch, which can solve the problems of large diode conduction loss in ordinary rectification and large reverse recovery loss when using MOSFET and its body diode for synchronous rectification; and When using MOSFET external parallel diode synchronous rectification, the current cannot be guaranteed to flow through the external parallel diode, which improves the efficiency of the circuit

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