CN-224233550-U - Flyback synchronous rectification circuit, switching power supply and power supply equipment

CN224233550UCN 224233550 UCN224233550 UCN 224233550UCN-224233550-U

Abstract

The utility model discloses a flyback synchronous rectification circuit, a switching power supply and power supply equipment, wherein the flyback synchronous rectification circuit comprises a transformer, a voltage output end, a rectification circuit connected with an output winding of the transformer and also connected with the voltage output end, the rectification circuit is used for rectifying output current of the output winding of the transformer and outputting the output current through the voltage output end, an RCD absorption circuit is connected between the rectification circuit and the voltage output end in series, the RCD absorption circuit is connected with the output winding of the transformer in parallel, and the RCD absorption circuit is used for absorbing peak voltage generated when the rectification circuit works. The utility model solves the problem of larger energy loss when the reverse peak voltage is absorbed in the rectifying circuit.

Inventors

NI HONGTAO

Assignees

数字创芯技术(深圳)有限公司

Dates

Publication Date: 20260512
Application Date: 20250418

Claims (10)

1. A flyback synchronous rectification circuit, comprising: A transformer; A voltage output terminal; The rectification circuit is connected with the output winding of the transformer and is also connected with the voltage output end, and the rectification circuit is used for rectifying the output current of the output winding of the transformer and then outputting the rectified current through the voltage output end; the RCD absorption circuit is connected in series between the rectifying circuit and the voltage output end, and is connected with the output winding of the transformer in parallel, and the RCD absorption circuit is used for absorbing the anti-peak voltage generated when the rectifying circuit works.
2. The flyback synchronous rectification circuit of claim 1, wherein said rectification circuit comprises: The positive end rectifying circuit is connected with the output winding of the transformer and is also connected with the voltage output end, and the positive end rectifying circuit is used for rectifying positive half-cycle alternating current output by the output winding of the transformer and then outputting the positive half-cycle alternating current through the voltage output end; The negative end rectifying circuit is connected with the output winding of the transformer and is also connected with the voltage output end, and the negative end rectifying circuit is used for rectifying the negative half-cycle alternating current output by the output winding of the transformer and then outputting the rectified negative half-cycle alternating current through the voltage output end.
3. The flyback synchronous rectification circuit of claim 2, wherein said positive side rectification circuit comprises a first MOS tube, a grid electrode of said first MOS tube is used for being connected with an external controller, a source electrode of said first MOS tube is connected with an output winding of said transformer, a drain electrode of said first MOS tube is connected with said voltage output end, said negative side rectification circuit comprises a second MOS tube, a grid electrode of said second MOS tube is used for being connected with an external controller, a source electrode of said second MOS tube is connected with said voltage output end, and a drain electrode of said second MOS tube is connected with an output winding of said transformer.
4. The flyback synchronous rectification circuit of claim 2, wherein said RCD snubber circuit comprises a positive side snubber circuit and a negative side snubber circuit, said positive side snubber circuit being connected in series between said positive side rectification circuit and said voltage output, said positive side snubber circuit being connected in parallel with an output winding of said transformer, said negative side snubber circuit being connected in series between said negative side rectification circuit and said voltage output, said negative side snubber circuit being connected in parallel with an output winding of said transformer.
5. The flyback synchronous rectification circuit of claim 4, wherein said positive side snubber circuit comprises a first resistor, a first capacitor and a first diode, said first resistor and said first capacitor are connected at a first end thereof to said voltage output terminal, said first resistor and said first capacitor are connected at a second end thereof to an anode of said first diode, and said first diode is connected at a cathode thereof to said positive side rectification circuit.
6. The flyback synchronous rectification circuit of claim 4, wherein said negative side snubber circuit comprises a second resistor, a second capacitor, and a second diode, said first terminal of said second resistor and said first terminal of said second capacitor being connected to said voltage output terminal, said second terminal of said second resistor and said second terminal of said second capacitor being connected to a cathode of said second diode, an anode of said second diode being connected to said positive side rectifier circuit.
7. The flyback synchronous rectification circuit of claim 1, the flyback synchronous rectification circuit is characterized by further comprising: And the filter circuit is connected with the rectifying circuit in parallel and is used for filtering the output voltage of the rectifying circuit and outputting the filtered voltage.
8. The flyback synchronous rectification circuit of claim 7, wherein said filter circuit comprises a third resistor and a third capacitor, a first end of said third resistor being connected to an input of said rectification circuit, a second end of said third resistor being connected to a first end of said third capacitor, and a second end of said third capacitor being connected to an output of said rectification circuit.
9. A switching power supply comprising a flyback synchronous rectification circuit as claimed in any one of claims 1 to 8.
10. A power supply device comprising the switching power supply of claim 9.

Description

Flyback synchronous rectification circuit, switching power supply and power supply equipment Technical Field The utility model relates to the field of flyback synchronous rectification circuits, switching power supplies and power supply equipment. Background The MOS tube is used as a rectifying device in the current rectifying circuit, and compared with a diode, the MOS tube has the advantages of low on-resistance, quick switching, higher current carrying capacity and the like, and in a switching power supply, the MOS tube is commonly used for synchronous rectification. In the working process, when the MOS tube is switched from an on state to an off state, the voltage between the drain electrode and the source electrode is instantaneously increased due to the change of current, and the anti-peak voltage is generated to influence the stability of the circuit. In the current rectifying circuit, an RC absorption circuit is usually arranged at two ends of the MOS tube to absorb the anti-peak voltage generated when the MOS tube works, however, in order to ensure a better absorption effect, the RC constant of the RC absorption circuit needs to be set larger, which can cause the energy loss of the circuit to be increased. Disclosure of Invention In view of the above-mentioned shortcomings of the prior art, an object of the present utility model is to provide a flyback synchronous rectification circuit, a switching power supply and a power supply device, so as to solve the problem of large energy loss when the flyback voltage is absorbed in the rectification circuit. The technical scheme of the utility model is as follows: The utility model provides a flyback synchronous rectification circuit, which comprises: A transformer; A voltage output terminal; The rectification circuit is connected with the output winding of the transformer and is also connected with the voltage output end, and the rectification circuit is used for rectifying the output current of the output winding of the transformer and then outputting the rectified current through the voltage output end; the RCD absorption circuit is connected in series between the rectifying circuit and the voltage output end, and is connected with the output winding of the transformer in parallel, and the RCD absorption circuit is used for absorbing the anti-peak voltage generated when the rectifying circuit works. Optionally, the rectifying circuit includes: The positive end rectifying circuit is connected with the output winding of the transformer and is also connected with the voltage output end, and the positive end rectifying circuit is used for rectifying positive half-cycle alternating current output by the output winding of the transformer and then outputting the positive half-cycle alternating current through the voltage output end; The negative end rectifying circuit is connected with the output winding of the transformer and is also connected with the voltage output end, and the negative end rectifying circuit is used for rectifying the negative half-cycle alternating current output by the output winding of the transformer and then outputting the rectified negative half-cycle alternating current through the voltage output end. Optionally, the positive end rectifying circuit comprises a first MOS tube, a grid electrode of the first MOS tube is used for being connected with an external controller, a source electrode of the first MOS tube is connected with an output winding of the transformer, a drain electrode of the first MOS tube is connected with the voltage output end, the negative end rectifying circuit comprises a second MOS tube, a grid electrode of the second MOS tube is used for being connected with the external controller, a source electrode of the second MOS tube is connected with the voltage output end, and a drain electrode of the second MOS tube is connected with the output winding of the transformer. Optionally, the RCD snubber circuit includes a positive side snubber circuit and a negative side snubber circuit, the positive side snubber circuit is connected in series between the positive side rectifier circuit and the voltage output terminal, the positive side snubber circuit is connected in parallel with the output winding of the transformer, the negative side snubber circuit is connected in series between the negative side rectifier circuit and the voltage output terminal, and the negative side snubber circuit is connected in parallel with the output winding of the transformer. Optionally, the positive-end absorption circuit includes a first resistor, a first capacitor and a first diode, wherein a first end of the first resistor and a first end of the first capacitor are connected with the voltage output end, a second end of the first resistor and a second end of the first capacitor are connected with an anode of the first diode, and a cathode of the first diode is connected with the positive-end rectification circuit. Optionally, the negativ