CN210780588U - Synchronous rectification circuit and switching power supply - Google Patents
Synchronous rectification circuit and switching power supply Download PDFInfo
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- CN210780588U CN210780588U CN201922264286.5U CN201922264286U CN210780588U CN 210780588 U CN210780588 U CN 210780588U CN 201922264286 U CN201922264286 U CN 201922264286U CN 210780588 U CN210780588 U CN 210780588U
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Abstract
The utility model discloses a synchronous rectification circuit and a switching power supply, wherein the synchronous rectification circuit comprises a PWM control module, a switching module, a conversion module, a synchronous rectification module, a feedback module, an output filtering module and a power supply module; the PWM control module is used for controlling the on-off of the switch module so as to control the input or off of the direct current; the conversion module is used for converting the direct current into preset output voltage and outputting the preset output voltage to external electric equipment through the output filtering module; the synchronous rectification module is used for synchronously rectifying the preset output voltage, and the feedback module is used for sampling the preset output voltage and then outputting a feedback signal to the PWM control module so that the PWM control module regulates the preset output voltage according to the feedback signal; the power supply module provides working current for the feedback module; the utility model discloses a simple circuit structure has realized switching power supply's synchronous rectification, the cost is reduced.
Description
Technical Field
The utility model relates to a switching power supply field, in particular to synchronous rectification circuit and switching power supply.
Background
The loss of the switching power supply mainly consists of 3 parts: loss of power switch tube, loss of high-frequency transformer, loss of output end rectifier tube. Under the condition of large current output, the conduction voltage drop of the rectifier diode is high, which causes the increase of the rectification loss and the reduction of the power efficiency. A new output rectifying circuit, namely a synchronous rectifying circuit, is needed, but the traditional synchronous rectifying circuit is controlled by a special integrated circuit, so that the structure of the circuit is complex and the cost is high.
Thus, the prior art has yet to be improved and enhanced.
SUMMERY OF THE UTILITY MODEL
In view of the foregoing disadvantages of the prior art, an object of the present invention is to provide a synchronous rectification circuit and a switching power supply, which can effectively simplify the structure of the synchronous rectification circuit and reduce the cost.
In order to achieve the purpose, the utility model adopts the following technical proposal:
a synchronous rectification circuit comprises a PWM control module, a switch module, a conversion module, a synchronous rectification module, a feedback module, an output filtering module and a power supply module; the PWM control module is used for controlling the on-off of the switch module so as to control the input or off of direct current; the conversion module is used for converting the direct current into preset output voltage and outputting the preset output voltage to external electric equipment through the output filtering module; the synchronous rectification module is used for synchronously rectifying the preset output voltage, and the feedback module is used for sampling the preset output voltage and then outputting a feedback signal to the PWM control module, so that the PWM control module regulates the preset output voltage according to the feedback signal; the power supply module provides working current for the feedback module.
In the synchronous rectification circuit, the synchronous rectification module comprises a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a first MOS (metal oxide semiconductor) tube and a second MOS tube; one end of the first capacitor is connected with the conversion module, and the other end of the first capacitor is connected with one end of the third resistor and the grid electrode of the second MOS tube through the first resistor; the other end of the third resistor is grounded with the source electrode of the second MOS tube; one end of the second capacitor is connected with the conversion module, the other end of the second capacitor is connected with one end of the fourth resistor and the grid electrode of the first MOS tube through the second resistor, the other end of the fourth resistor and the source electrode of the first MOS tube are grounded, and the drain electrode of the first MOS tube and the drain electrode of the second MOS tube are both connected with the conversion module.
In the synchronous rectification circuit, the switch module comprises a third MOS tube and a fourth MOS tube; the grid electrode of the third MOS tube and the grid electrode of the fourth MOS tube are both connected with the PWM control module; the drain electrode of the third MOS tube is connected with the direct current input end, the source electrode of the third MOS tube and the drain electrode of the fourth MOS tube are both connected with the conversion module, and the source electrode of the fourth MOS tube is grounded.
In the synchronous rectification circuit, the conversion module comprises a transformer and a third capacitor; a 1 st pin of the transformer is connected with a source electrode of the third MOS tube, a 2 nd pin of the transformer is grounded through the third capacitor, and a 3 rd pin of the transformer is connected with one end of the first capacitor and a drain electrode of the first MOS tube; the 4 th pin of the transformer is connected with a VO + signal end; a 5 th pin of the transformer is connected with one end of the second capacitor and the drain electrode of the second MOS tube; and the 6 th pin of the transformer is connected with the power supply module.
In the synchronous rectification circuit, the PWM control module comprises a PWM control chip, and the PWM control chip is respectively connected with the grid electrode of the third MOS tube and the grid electrode of the fourth MOS tube.
In the synchronous rectification circuit, the power supply module comprises a fifth resistor, a diode and a fourth capacitor; one end of the fifth resistor is connected with a pin 6 of the transformer, the other end of the fifth resistor is connected with the anode of the diode, the cathode of the diode is connected with one end of the fourth capacitor and the feedback module, and the other end of the fourth capacitor is grounded.
In the synchronous rectification circuit, the feedback module comprises a sixth resistor, a seventh resistor, an eighth resistor, a reference voltage source, a fifth capacitor and a photoelectric coupler; one end of the sixth resistor is connected with the cathode of the diode, the other end of the sixth resistor is connected with a 1 st pin of the photoelectric coupler, and a 2 nd pin of the photoelectric coupler is connected with the cathode of the reference voltage source; one end of the fifth capacitor, one end of the eighth resistor and one end of the seventh resistor are connected with the reference end of the reference voltage source, the anode of the reference voltage source, the other end of the fifth capacitor and the other end of the eighth resistor are grounded, and the other end of the seventh resistor is connected with the 4 th pin of the transformer.
In the synchronous rectification circuit, the output filter module comprises a sixth capacitor, one end of the sixth capacitor is connected with the 4 th pin of the transformer and the VO + signal end, and the end of the sixth capacitor is grounded.
A switching power supply comprising a synchronous rectification circuit as described above.
Compared with the prior art, the utility model provides a synchronous rectification circuit and switching power supply, synchronous rectification circuit includes PWM control module, switch module, conversion module, synchronous rectification module, feedback module, output filter module and power module; the PWM control module is used for controlling the on-off of the switch module so as to control the input or off of the direct current; the conversion module is used for converting the direct current into preset output voltage and outputting the preset output voltage to external electric equipment through the output filtering module; the synchronous rectification module is used for synchronously rectifying the preset output voltage, and the feedback module is used for sampling the preset output voltage and then outputting a feedback signal to the PWM control module so that the PWM control module regulates the preset output voltage according to the feedback signal; the power supply module provides working current for the feedback module; the utility model discloses a simple circuit structure has realized switching power supply's synchronous rectification, the cost is reduced.
Drawings
Fig. 1 is a block diagram of a synchronous rectification circuit provided by the present invention;
fig. 2 is a schematic circuit diagram of the synchronous rectification circuit provided by the present invention.
Detailed Description
The utility model provides a synchronous rectification circuit and switching power supply can effectively simplify synchronous rectification circuit's structure, the cost is reduced.
In order to make the objects, technical solutions and effects of the present invention clearer and clearer, the following description of the present invention will refer to the accompanying drawings and illustrate embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention.
Referring to fig. 1, the present invention provides a synchronous rectification circuit, which includes a PWM control module 100, a switch module 200, a conversion module 300, a synchronous rectification module 400, a feedback module 500, an output filter module 600, and a power supply module 700; the PWM control module 100 is connected to the switch module 200, the switch module 200 is connected to a dc power supply and the conversion module 300, the conversion module 300 is connected to the synchronous rectification module 400, the power supply module 700 and the output filter module 600, and the output filter module 600 is further connected to an output voltage output terminal.
The PWM control module 100 is configured to control the switch module 200 to be turned on or off, so as to control the input or off of the dc power; the conversion module 300 is configured to convert the direct current into a preset output voltage, and output the preset output voltage to an external power device through the output filter module 600; the synchronous rectification module 400 is configured to perform synchronous rectification on the preset output voltage, and the feedback module 500 is configured to sample the preset output voltage and output a feedback signal to the PWM control module 100, so that the PWM control module 100 adjusts the preset output voltage according to the feedback signal; power module 700 does feedback module 500 provides operating current, the utility model discloses a simple circuit design has simplified synchronous rectification circuit's structure, can effectively practice thrift the cost.
Further, referring to fig. 2, the synchronous rectification module 400 includes a first capacitor C1, a second capacitor C2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first MOS transistor V1, and a second MOS transistor V2; one end of the first capacitor C1 is connected to the conversion module 300, and the other end of the first capacitor C1 is connected to one end of the third resistor R3 and the gate of the second MOS transistor V2 through the first resistor R1; the other end of the third resistor R3 and the source of the second MOS transistor V2 are grounded; one end of the second capacitor C2 is connected to the conversion module 300, the other end of the second capacitor C2 is connected to one end of the fourth resistor R4 and the gate of the first MOS transistor V1 through the second resistor R2, the other end of the fourth resistor R4 and the source of the first MOS transistor V1 are grounded, the drain of the first MOS transistor V1 and the drain of the second MOS transistor V2 are both connected to the conversion module 300, and the first MOS transistor V1 and the second MOS transistor V2 are rectification MOS transistors.
Specifically, the driving voltages of the first MOS transistor V1 and the second MOS transistor V2 are derived from the output voltage outputted from the conversion module 300 and are applied between the gate and the drain of the first MOS transistor V1 through the second capacitor C2 and the second resistor R2R 2; the first capacitor C1 and the first resistor R1 are added between the gate and the drain of the second MOS transistor V2, because the switching states of the first MOS transistor V1 and the second MOS transistor V2 are interlocked, one MOS transistor is on, the other MOS transistor is off, the first MOS transistor V1 and the second MOS transistor V2 have an anti-parallel diode parasitic in vivo, the parallel diodes of the first MOS transistor V1 and the second MOS transistor V2 are already turned on before the actual turn-on, the levels of the source S and the drain D of the MOS transistors relative to the gate are kept consistent, and the first MOS transistor V1 and the second MOS transistor V2 are alternately turned on or off according to the output voltage, so that the gate voltage of the rectifying MOS transistor is always kept synchronous with the phase of the rectified voltage to complete synchronous rectification.
Further, the switch module 200 includes a third MOS transistor V3 and a fourth MOS transistor V4; the grid electrode of the third MOS transistor V3 and the grid electrode of the fourth MOS transistor V4 are both connected with the PWM control module 100; the drain of the third MOS transistor V3 is connected to the dc input terminal, the source of the third MOS transistor V3 and the drain of the fourth MOS transistor V4 are both connected to the conversion module 300, the source of the fourth MOS transistor V4 is grounded, and the PWM control module 100 outputs a periodically alternating high-level driving voltage and low-level driving voltage to drive the third MOS transistor V3 and the fourth MOS transistor V4 to be alternately turned on or off, so as to control the input or off of the dc power supply; specifically, when the third MOS transistor V3 is turned on, the fourth MOS transistor V4 is turned off, the dc power input from the VD signal terminal is sent to the ground through the third MOS transistor V3 and the conversion module 300, and the conversion module 300 stores the electric energy according to the dc power and outputs a preset output voltage to the output filter module 600; when the third MOS transistor V3 is turned off and the fourth MOS transistor V4 is turned on, the dc power is turned off, the conversion module 300 outputs a corresponding preset output voltage according to the stored electric energy, and completes a switching cycle and cycles to provide electric energy, and the circuit structure is simple.
Further, the conversion module 300 includes a transformer T1 and a third capacitor C3; the 1 st pin of the transformer T1 is connected to the source of the third MOS transistor V3, the 2 nd pin of the transformer T1 is grounded through the third capacitor C3, and the 3 rd pin of the transformer T1 is connected to one end of the first capacitor C1 and the drain of the first MOS transistor V1; the 4 th pin of the transformer T1 is connected with a VO + signal end; a 5 th pin of the transformer T1 is connected with one end of the second capacitor C2 and the drain of the second MOS transistor V2; the pin 6 of the transformer T1 is connected to the power supply module 700, when the third MOS transistor V3 is turned on, the fourth MOS transistor V4 is turned off, the direct current passes through the third MOS transistor V3 and the primary winding N1 of the transformer T1 to the first capacitor C1, from the first capacitor C1 to ground, the first capacitor C1 stores electric energy in the process, and at the same time, the transferred energy of the transformer T1 is transferred to the secondary winding; when the third MOS transistor V3 is turned off and the fourth MOS transistor V4 is turned on, the energy stored in the first capacitor C1 is released to the secondary winding through the fourth MOS transistor V4 and the primary winding of the transformer T1; correspondingly, when the dotted terminal of the secondary winding N2 of the transformer T1 is positive, the gate-drain voltage of the second MOS transistor V2 is positive and turns on, and the first MOS transistor V1 is turned off; when the end with the same name of the secondary winding N2 of the transformer T1 is negative, the first MOS transistor V1 is conducted, and the second MOS transistor V2 is closed, so that the gate voltage of the rectifying MOS transistor is always consistent with the phase of the rectified voltage, namely, synchronous rectification is realized through a simple circuit structure.
Further, please continue to refer to fig. 2, the PWM control module 100 includes a PWM control chip, the PWM control chip is respectively connected to the gate of the third MOS transistor V3 and the gate of the fourth MOS transistor V4, the model of the PWM control chip in this embodiment is L6599, and certainly, in other embodiments, the PWM control chip with the same function may be selected, which is not limited by the present invention.
Further, the power supply module 700 includes a fifth resistor R5, a diode D1, and a fourth capacitor C4; one end of the fifth resistor R5 is connected to the 6 th pin of the transformer T1, the other end of the fifth resistor R5 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to one end of the fourth capacitor C4 and the feedback module 500, and the other end of the fourth capacitor C4 is grounded, wherein the secondary winding N4 of the transformer T1 is current-limited by the fifth resistor R5, rectified by the diode D1, and finally filtered by the fourth capacitor C4, so that the feedback module 500 is supplied with safe and reliable working current, and the normal operation of the feedback module 500 is ensured.
Further, the feedback module 500 includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a reference voltage source IC2, a fifth capacitor C5, and a photocoupler IC 1; one end of the sixth resistor R6 is connected to the negative electrode of the diode D1, the other end of the sixth resistor R6 is connected to the 1 st pin of the photocoupler IC1, and the 2 nd pin of the photocoupler IC1 is connected to the cathode of the reference voltage source IC 2; one end of the fifth capacitor C5, one end of the eighth resistor R8, and one end of the seventh resistor R7 are connected to the reference end of the reference voltage source IC2, the anode of the reference voltage source IC2, the other end of the fifth capacitor C5, and the other end of the eighth resistor R8 are grounded, the other end of the seventh resistor R7 is connected to the 4 th pin of the transformer T1, and the seventh resistor R7 and the eighth resistor R8 divide and sample the output voltage to obtain a feedback signal and output the feedback signal to the PWM control chip, so as to control the duty ratio of the driving signal output by the PWM control chip and further adjust and maintain the stability of the output voltage.
Furthermore, the output filtering module 600 includes a sixth capacitor C6, one end of the sixth capacitor C6 is connected to the 4 th pin of the transformer T1 and the VO + signal terminal, the terminal of the sixth capacitor C6 is grounded, and the output voltage is filtered by the sixth capacitor C6 and then output to an external electric device, so as to ensure the stability of the output voltage; the utility model discloses a simple electronic component design commonly used obtains synchronous rectification circuit, has simplified synchronous rectification circuit's structure, the cost is reduced.
The utility model also provides a switching power supply, switching power supply includes as above synchronous rectification circuit, because the above has carried out detailed description to this synchronous rectification circuit, no longer gives details here.
To sum up, the utility model provides a synchronous rectification circuit and switching power supply, synchronous rectification circuit includes PWM control module, switch module, conversion module, synchronous rectification module, feedback module, output filter module and power module; the PWM control module is used for controlling the on-off of the switch module so as to control the input or off of direct current; the conversion module is used for converting the direct current into preset output voltage and outputting the preset output voltage to external electric equipment through the output filtering module; the synchronous rectification module is used for synchronously rectifying the preset output voltage, and the feedback module is used for sampling the preset output voltage and then outputting a feedback signal to the PWM control module, so that the PWM control module regulates the preset output voltage according to the feedback signal; the power supply module provides working current for the feedback module; the utility model discloses a simple circuit structure has realized switching power supply's synchronous rectification, the cost is reduced.
It should be understood that equivalent alterations and modifications can be made by those skilled in the art according to the technical solution of the present invention and the inventive concept thereof, and all such alterations and modifications should fall within the scope of the appended claims.
Claims (9)
1. A synchronous rectification circuit is characterized by comprising a PWM control module, a switch module, a conversion module, a synchronous rectification module, a feedback module, an output filtering module and a power supply module; the PWM control module is used for controlling the on-off of the switch module so as to control the input or off of direct current; the conversion module is used for converting the direct current into preset output voltage and outputting the preset output voltage to external electric equipment through the output filtering module; the synchronous rectification module is used for synchronously rectifying the preset output voltage, and the feedback module is used for sampling the preset output voltage and then outputting a feedback signal to the PWM control module, so that the PWM control module regulates the preset output voltage according to the feedback signal; the power supply module provides working current for the feedback module.
2. The synchronous rectification circuit of claim 1, wherein the synchronous rectification module comprises a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a first MOS transistor and a second MOS transistor; one end of the first capacitor is connected with the conversion module, and the other end of the first capacitor is connected with one end of the third resistor and the grid electrode of the second MOS tube through the first resistor; the other end of the third resistor is grounded with the source electrode of the second MOS tube; one end of the second capacitor is connected with the conversion module, the other end of the second capacitor is connected with one end of the fourth resistor and the grid electrode of the first MOS tube through the second resistor, the other end of the fourth resistor and the source electrode of the first MOS tube are grounded, and the drain electrode of the first MOS tube and the drain electrode of the second MOS tube are both connected with the conversion module.
3. The synchronous rectification circuit of claim 2, wherein the switch module comprises a third MOS transistor and a fourth MOS transistor; the grid electrode of the third MOS tube and the grid electrode of the fourth MOS tube are both connected with the PWM control module; the drain electrode of the third MOS tube is connected with the direct current input end, the source electrode of the third MOS tube and the drain electrode of the fourth MOS tube are both connected with the conversion module, and the source electrode of the fourth MOS tube is grounded.
4. The synchronous rectification circuit of claim 3, wherein the conversion module comprises a transformer and a third capacitor; a 1 st pin of the transformer is connected with a source electrode of the third MOS tube, a 2 nd pin of the transformer is grounded through the third capacitor, and a 3 rd pin of the transformer is connected with one end of the first capacitor and a drain electrode of the first MOS tube; the 4 th pin of the transformer is connected with a VO + signal end; a 5 th pin of the transformer is connected with one end of the second capacitor and the drain electrode of the second MOS tube; and the 6 th pin of the transformer is connected with the power supply module.
5. The synchronous rectification circuit of claim 3, wherein the PWM control module comprises a PWM control chip, and the PWM control chip is respectively connected with the grid electrode of the third MOS tube and the grid electrode of the fourth MOS tube.
6. The synchronous rectification circuit of claim 4, wherein the power supply module comprises a fifth resistor, a diode and a fourth capacitor; one end of the fifth resistor is connected with a pin 6 of the transformer, the other end of the fifth resistor is connected with the anode of the diode, the cathode of the diode is connected with one end of the fourth capacitor and the feedback module, and the other end of the fourth capacitor is grounded.
7. The synchronous rectification circuit of claim 6, wherein the feedback module comprises a sixth resistor, a seventh resistor, an eighth resistor, a reference voltage source, a fifth capacitor and an opto-coupler; one end of the sixth resistor is connected with the cathode of the diode, the other end of the sixth resistor is connected with a 1 st pin of the photoelectric coupler, and a 2 nd pin of the photoelectric coupler is connected with the cathode of the reference voltage source; one end of the fifth capacitor, one end of the eighth resistor and one end of the seventh resistor are connected with the reference end of the reference voltage source, the anode of the reference voltage source, the other end of the fifth capacitor and the other end of the eighth resistor are grounded, and the other end of the seventh resistor is connected with the 4 th pin of the transformer.
8. The synchronous rectification circuit of claim 4, wherein the output filter module comprises a sixth capacitor, one end of the sixth capacitor is connected to pin 4 of the transformer and the VO + signal terminal, and the end of the sixth capacitor is grounded.
9. A switching power supply comprising a synchronous rectification circuit according to any one of claims 1 to 8.
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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CN114726068A (en) * | 2022-03-27 | 2022-07-08 | 广东新佳盟电子科技有限公司 | Charging management circuit |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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CN114726068A (en) * | 2022-03-27 | 2022-07-08 | 广东新佳盟电子科技有限公司 | Charging management circuit |
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