Novel synchronous rectification control drive circuit

Abstract

The utility model discloses a novel synchronous rectification control drive circuit, which is applied to a DC-DC converter and comprises a first synchronous rectification MOS tube Q2, a second synchronous rectification MOS tube Q4, an output filter capacitor C43, a drive rectifier tube circuit and a current reverse flow prevention circuit. According to the utility model, synchronous rectification driving control is realized with fewer devices, reverse flow of output current is effectively prevented by arranging the current reverse flow prevention circuit, and the reliability of the power supply is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to DC-DC converter technical field, specifically a kind of novel synchronous rectification control drive circuit. BACKGROUND

[0002] DC-DC converter is a kind of DC basic power supply into other voltage species DC conversion device.In DC-DC converter, output low-voltage large current application occasion more and more, for this application occasion, the synchronous rectification circuit is generally applied in industry currently, to improve conversion efficiency.

[0003] The utility model discloses a synchronous rectification control circuit with the publication number CN209134310U: including power module, degaussing time detection circuit, output voltage detection circuit, synchronous rectification logic circuit, drive circuit, VD pin, GT pin, FB pin and VSS pin;VD pin is used to connect the drain end of synchronous rectification MOS pipe, GT pin is used to connect the grid end of synchronous rectification MOS pipe, VSS pin is used to connect the source end of synchronous rectification MOS pipe, FB pin is used to connect the voltage output end of converter.The synchronous rectification control circuit realizes that different power level power supply system can normally work in full temperature range.

[0004] However, the above-mentioned synchronous rectification control circuit structure is relatively complex, and more devices need to be used to meet the synchronous rectification drive control, and there is a lack of anti-current back-priming design, which cannot effectively prevent the reverse flow of output current. UTILITY MODEL CONTENT

[0005] In order to overcome the problem that the synchronous rectification control circuit in the prior art has a complex structure and cannot effectively prevent the reverse flow of output current, the utility model provides a novel synchronous rectification control drive circuit.

[0006] The utility model technical scheme is as follows:

[0007] The utility model relates to a novel synchronous rectification control drive circuit is applied to DC-DC converter, including first synchronous rectification MOS pipe Q2, second synchronous rectification MOS pipe Q4, output filter capacitor C43, drive rectifier circuit and prevent current anti -backfill circuit, the first end of first synchronous rectification MOS pipe Q2 is connected with the one end of first main transformer secondary winding T2 of DC-DC converter B, the first end of prevent current anti -backfill circuit and first node A1 respectively, the first end of second synchronous rectification MOS pipe Q4 is connected with the one end of second main transformer secondary winding T2 of DC-DC converter C, the second end of first synchronous rectification MOS pipe Q2 is connected with the second end of second synchronous rectification MOS pipe Q4, the one end of output filter capacitor C43 and analog ground AGND respectively, the other end of output filter capacitor C43 is connected with the other end of first main transformer secondary winding T2 B, the other end of second main transformer secondary winding T2 C and output voltage VOUT+ respectively, the third end of first synchronous rectification MOS pipe Q2 is connected with the one end of drive transformer winding T3 of DC-DC converter E, the second end of prevent current anti -backfill circuit, the first end of drive rectifier circuit and second node G1 respectively, the third end of second synchronous rectification MOS pipe Q4 is connected with the other end of drive transformer winding T3 E, the second end of drive rectifier circuit and third node G2 respectively, the third end of drive rectifier circuit is connected with the third end of prevent current anti -backfill circuit.

[0008] As a preferred scheme of the utility model, the drive rectifier circuit comprises a first drive rectifier Q49-A, a second drive rectifier Q49-B, a resistor R64, and a capacitor C19. The first end of the first drive rectifier Q49-A is connected with the second end of the second drive rectifier Q49-B and the one end of the drive transformer winding T3-E respectively. The second end of the first drive rectifier Q49-A is connected with the first end of the second drive rectifier Q49-B and the other end of the drive transformer winding T3-E respectively. The third end of the first drive rectifier Q49-A is connected with the third end of the second drive rectifier Q49-B, the one end of the resistor R64, and the one end of the capacitor C19 respectively. The other end of the resistor R64 is connected with the other end of the capacitor C19, the third end of the prevent current anti-backfill circuit, and the ground respectively.

[0009] As a preferred scheme of the utility model, the first drive rectifier Q49-A is an NMOS tube with a bidirectional breakdown diode and a damping diode.

[0010] As a preferred scheme of the utility model, the second drive rectifier Q49-B is an NMOS tube with a bidirectional breakdown diode and a damping diode.

[0011] As one preferred scheme of the utility model, the anti-current backflow circuit includes diode D1, triode Q33, capacitor R60, capacitor C23, diode D11, resistor R70, capacitor C33 and diode D14, the positive pole of diode D1 is connected with second node G1 and one end of capacitor C33 respectively, the negative pole of diode D1 is connected with the collector of triode Q33, the emitter of triode Q33 is connected with the third end of driving rectifier tube circuit after passing through capacitor R60, the base of triode Q33 is connected with one end of capacitor C23, the positive pole of diode D11 and one end of resistor R70 respectively, the negative pole of diode D11 is connected with first node A1, the other end of resistor R70 is connected with the other end of capacitor C33 and the negative pole of diode D14 respectively, the other end of capacitor C23 and the positive pole of diode D14 are all grounded.

[0012] As one preferred scheme of the utility model, triode Q33 is NPN type triode.

[0013] As one preferred scheme of the utility model, the first synchronous rectification MOS tube Q2 is eight-pin MOS tube.

[0014] As one preferred scheme of the utility model, the first to third pins of the first synchronous rectification MOS tube Q2 are connected with analog ground AGND, the fourth pin of the first synchronous rectification MOS tube Q2 is connected with second node G1, and the fifth to eighth pins of the first synchronous rectification MOS tube Q2 are all connected with first node A1.

[0015] As one preferred scheme of the utility model, the second synchronous rectification MOS tube Q4 is eight-pin MOS tube.

[0016] As one preferred scheme of the utility model, the first to third pins of the second synchronous rectification MOS tube Q4 are connected with analog ground AGND, the fourth pin of the second synchronous rectification MOS tube Q4 is connected with third node G2, and the fifth to eighth pins of the second synchronous rectification MOS tube Q4 are all connected with one end of second main transformer secondary winding T2-C.

[0017] Compared with the prior art, the utility model has the beneficial effects that:

[0018] The novel synchronous rectification control driving circuit provided by the utility model has the advantages that through the simplified design, the synchronous rectification driving control is realized by using less devices, the complexity of the circuit is reduced, the fault points and the maintenance cost caused by too many devices are reduced, meanwhile, the output current reverse flow is effectively prevented by arranging the anti-current reverse flow circuit, when the power supply is in no-load state and the current of the synchronous rectification MOS tube flows reversely, the anti-current reverse flow circuit can rapidly respond, the current reverse flow protection is realized by reducing the driving voltage of the synchronous rectification MOS tube, and therefore the reliability of the power supply is improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the utility model, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description, obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0020] Figure 1 It is the circuit diagram of the novel synchronous rectification control driving circuit in an embodiment of the utility model;

[0021] Figure 2 It is the circuit diagram of the driving rectifier tube circuit in an embodiment of the utility model;

[0022] Figure 3 It is the circuit diagram of the anti-current reverse flow circuit in an embodiment of the utility model. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the utility model more clearly, the following will further describe the utility model in combination with the drawings and embodiments.It should be noted that similar signs and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.It is declared that the following described embodiments are only used for explaining the utility model, and are not used for limiting the utility model.

[0024] It should be noted that the terms such as "mounting", "arranging", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can be detachable connection, or can be integrated, can be mechanical connection, can be electrical connection, can be directly connected, can be indirectly connected through an intermediate medium, can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited.

[0025] Please refer to Figures 1 to 3The embodiment provides a novel synchronous rectification control driving circuit applied to a DC-DC converter, which comprises a first synchronous rectification MOS tube Q2, a second synchronous rectification MOS tube Q4, an output filter capacitor C43, a driving rectifier circuit 1 and a current anti-backflow circuit 2, one end of a first main transformer secondary winding T2-B of the DC-DC converter, a first end of the current anti-backflow circuit 2 and a first node A1 are connected to the first end of the first synchronous rectification MOS tube Q2, one end of a second main transformer secondary winding T2-C of the DC-DC converter is connected to the first end of the second synchronous rectification MOS tube Q4, the second end of the first synchronous rectification MOS tube Q2 is connected to the second end of the second synchronous rectification MOS tube Q4, one end of the output filter capacitor C43 and an analog ground AGND, the other end of the output filter capacitor C43 is connected to the other end of the first main transformer secondary winding T2-B, the other end of the second main transformer secondary winding T2-C and an output voltage VOUT+, the third end of the first synchronous rectification MOS tube Q2 is connected to one end of a driving transformer winding T3-E of the DC-DC converter, the second end of the current anti-backflow circuit 2, the first end of the driving rectifier circuit 1 and a second node G1, the third end of the second synchronous rectification MOS tube Q4 is connected to the other end of the driving transformer winding T3-E, the second end of the driving rectifier circuit 1 and a third node G2, and the third end of the driving rectifier circuit 1 is connected to the third end of the current anti-backflow circuit 2.

[0026] Specifically, the driving rectifier circuit 1 comprises a first driving rectifier Q49-A, a second driving rectifier Q49-B, a resistor R64 and a capacitor C19, the first end of the first driving rectifier Q49-A is connected to the second end of the second driving rectifier Q49-B and one end of the driving transformer winding T3-E, the second end of the first driving rectifier Q49-A is connected to the first end of the second driving rectifier Q49-B and the other end of the driving transformer winding T3-E, the third end of the first driving rectifier Q49-A is connected to the third end of the second driving rectifier Q49-B, one end of the resistor R64 and one end of the capacitor C19, the other end of the resistor R64 is connected to the other end of the capacitor C19, the third end of the current anti-backflow circuit 2 and the ground.

[0027] Specifically, the anti-current backflow circuit 2 comprises a diode D1, a triode Q33, a capacitor R60, a capacitor C23, a diode D11, a resistor R70, a capacitor C33 and a diode D14. The positive pole of the diode D1 is connected with the second node G1 and one end of the capacitor C33 respectively, the negative pole of the diode D1 is connected with the collector of the triode Q33, the emitter of the triode Q33 is connected with the third end of the driving rectifier circuit 1 through the capacitor R60, the base of the triode Q33 is connected with one end of the capacitor C23, the positive pole of the diode D11 and one end of the resistor R70 respectively, the negative pole of the diode D11 is connected with the first node A1, the other end of the resistor R70 is connected with the other end of the capacitor C33 and the negative pole of the diode D14 respectively, and the other end of the capacitor C23 and the positive pole of the diode D14 are grounded. The triode Q33 is an NPN triode, which can control the on-off of the circuit or change the working state of the circuit according to the change of the input signal. In the anti-current backflow circuit 2, the triode Q33 controls the conduction and cut-off of the circuit according to the voltage change of the first node A1, thereby preventing the reverse flow of the output current.

[0028] Working principle:

[0029] When the power supply works normally, the primary winding of the main transformer of the DC-DC converter, the first synchronous rectification MOS tube Q2 and the second synchronous rectification MOS tube Q4 are provided by the driving transformer of the DC-DC converter, and the resistor R64 is equivalent to the driving resistor of the first synchronous rectification MOS tube Q2 and the second synchronous rectification MOS tube Q4. At this time, the voltage at the first node A1 (i.e. the first end) of the anti-current backflow circuit 2 is lower than the voltage of the analog ground AGND, the diode D11 is turned on, the voltage at the second node G1 (i.e. the second end) of the anti-current backflow circuit 2 forms a loop through the capacitor C33, the resistor R70 and the diode D11, and the driving voltage of the first synchronous rectification MOS tube Q2 and the second synchronous rectification MOS tube Q4 is the voltage across the winding T3-E of the driving transformer.

[0030] When the power supply is in no-load state, the output current is zero, and if the current of the first synchronous rectification MOS tube Q2 and the second synchronous rectification MOS tube Q4 flows reversely, the voltage at the first node A1 (i.e. the first end) of the anti-current backflow circuit 2 is higher than the voltage of the analog ground AGND, at this time, the capacitor C33, the triode Q33 and the resistor R30 of the anti-current backflow circuit 2 are turned on, and the driving voltage of the first synchronous rectification MOS tube Q2 and the second synchronous rectification MOS tube Q4 is the voltage across the winding T3-E of the driving transformer minus the voltage across the capacitor C19, thereby realizing the protection of the reverse current flow by reducing the driving voltage of the synchronous rectification MOS tube.

[0031] The novel synchronous rectification control driving circuit has the advantages that: through the simplified design, fewer devices are used to realize the synchronous rectification driving control, not only the complexity of the circuit is reduced, but also the fault points and maintenance costs caused by too many devices are reduced; meanwhile, the anti-current backflow circuit 2 is arranged to effectively prevent the output current from flowing reversely; when the power supply is in the no-load state and the current of the synchronous rectification MOS tube flows reversely, the anti-current backflow circuit 2 can quickly respond and realize the current reverse flow protection by reducing the driving voltage of the synchronous rectification MOS tube, thereby improving the reliability of the power supply.

[0032] Please refer to Figure 2 In an embodiment, the first driving rectifier tube Q49-A and the second driving rectifier tube Q49-B are both NMOS tubes with a bidirectional breakdown diode and a damping diode, so that the first driving rectifier tube Q49-A and the second driving rectifier tube Q49-B are used not only as rectifier tubes in the circuit, but also provide additional circuit protection functions through the built-in bidirectional breakdown diode and damping diode, so that the circuit can maintain stable operation when facing abnormal conditions such as voltage transients and surges, thereby improving the reliability and stability of the circuit.

[0033] Please refer to Figure 1 In an embodiment, the first synchronous rectification MOS tube Q2 and the second synchronous rectification MOS tube Q4 are both eight-pin MOS tubes. The first to third pins of the first synchronous rectification MOS tube Q2 are connected with the analog ground AGND, the fourth pin of the first synchronous rectification MOS tube Q2 is connected with the second node G1, and the fifth to eighth pins of the first synchronous rectification MOS tube Q2 are connected with the first node A1. The first to third pins of the second synchronous rectification MOS tube Q4 are connected with the analog ground AGND, the fourth pin of the second synchronous rectification MOS tube Q4 is connected with the third node G2, and the fifth to eighth pins of the second synchronous rectification MOS tube Q4 are connected with one end of the second main transformer secondary winding T2-C. In the novel synchronous rectification control driving circuit, the first synchronous rectification MOS tube Q2 and the second synchronous rectification MOS tube Q4 are both eight-pin MOS tubes, and through the specific pin connection mode, the efficient synchronous rectification and power conversion functions are realized. Meanwhile, they are connected with the anti-current backflow circuit 2 and the driving rectifier tube circuit 1, and together constitute a stable and reliable power supply system, which not only improves the efficiency and stability of the power supply, but also reduces the power consumption and cost of the system.

[0034] It should be understood that those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall fall within the protection scope of the appended claims of the present application.

[0035] The utility model discloses has been described exemplarily above in combination with the drawing, obviously the implementation of the utility model patent is not limited by above-mentioned mode, as long as the various improvements of the method concept and technical scheme of the utility model patent are adopted, or the concept and technical scheme of the utility model patent are directly applied to other occasions without improvement, all are within the protection scope of the utility model.

Claims

1. A novel synchronous rectification control drive circuit applied in a DC-DC converter, characterized in that, The first synchronous rectification MOS tube Q2, the second synchronous rectification MOS tube Q4, the output filter capacitor C43, the driving rectifier circuit and the anti-current backflow circuit are connected, one end of the first main transformer secondary winding T2-B of the DC-DC converter, the first end of the anti-current backflow circuit and the first node A1 are connected to the first end of the first synchronous rectification MOS tube Q2, one end of the second main transformer secondary winding T2-C of the DC-DC converter is connected to the first end of the second synchronous rectification MOS tube Q4, the second end of the first synchronous rectification MOS tube Q2, one end of the output filter capacitor C43 and the analog ground AGND are connected to the second end of the second synchronous rectification MOS tube Q4, the other end of the output filter capacitor C43 is connected to the other end of the first main transformer secondary winding T2-B, the other end of the second main transformer secondary winding T2-C and the output voltage VOUT+, the first end of the driving rectifier circuit, the second end of the anti-current backflow circuit, the first end of the driving rectifier circuit and the second node G1 are connected to the third end of the first synchronous rectification MOS tube Q2, the other end of the driving transformer winding T3-E, the second end of the driving rectifier circuit and the third node G2 are connected to the third end of the second synchronous rectification MOS tube Q4, and the third end of the driving rectifier circuit is connected to the third end of the anti-current backflow circuit.

2. The novel synchronous rectification control driving circuit according to claim 1, characterized in that, The driving rectifier circuit comprises a first driving rectifier Q49-A, a second driving rectifier Q49-B, a resistor R64 and a capacitor C19, the first end of the first driving rectifier Q49-A is connected to the second end of the second driving rectifier Q49-B and one end of the driving transformer winding T3-E, the second end of the first driving rectifier Q49-A is connected to the first end of the second driving rectifier Q49-B and the other end of the driving transformer winding T3-E, the third end of the first driving rectifier Q49-A is connected to the third end of the second driving rectifier Q49-B, one end of the resistor R64 and one end of the capacitor C19, the other end of the resistor R64 is connected to the other end of the capacitor C19, the third end of the anti-current backflow circuit and the ground.

3. The novel synchronous rectification control driving circuit according to claim 2, characterized in that, The first driving rectifier Q49-A is an NMOS tube with a bidirectional breakdown diode and a damping diode.

4. The novel synchronous rectification control driving circuit according to claim 2, characterized in that, The second driving rectifier Q49-B is an NMOS tube with a bidirectional breakdown diode and a damping diode.

5. The novel synchronous rectification control driving circuit according to claim 1, characterized in that, The anti-current backflow circuit comprises a diode D1, a triode Q33, a capacitor R60, a capacitor C23, a diode D11, a resistor R70, a capacitor C33 and a diode D14, the positive pole of the diode D1 is connected with the second node G1 and one end of the capacitor C33 respectively, the negative pole of the diode D1 is connected with the collector of the triode Q33, the emitter of the triode Q33 is connected with the third end of the driving rectifier circuit through the capacitor R60, the base of the triode Q33 is connected with one end of the capacitor C23, the positive pole of the diode D11 and one end of the resistor R70 respectively, the negative pole of the diode D11 is connected with the first node A1, the other end of the resistor R70 is connected with the other end of the capacitor C33 and the negative pole of the diode D14 respectively, and the other end of the capacitor C23 and the positive pole of the diode D14 are grounded.

6. The novel synchronous rectification control drive circuit according to claim 5, characterized by, The triode Q33 is an NPN triode.

7. The novel synchronous rectification control driving circuit according to claim 1, characterized in that, The first synchronous rectification MOS Q2 is an eight-pin MOS.

8. The novel synchronous rectification control driving circuit according to claim 7, characterized in that, The first to third pins of the first synchronous rectification MOS Q2 are connected with the analog ground AGND, the fourth pin of the first synchronous rectification MOS Q2 is connected with the second node G1, and the fifth to eighth pins of the first synchronous rectification MOS Q2 are connected with the first node A1.

9. The novel synchronous rectification control driving circuit according to claim 1, characterized in that, The second synchronous rectification MOS Q4 is an eight-pin MOS.

10. The novel synchronous rectification control drive circuit according to claim 9, characterized in that, The first to third pins of the second synchronous rectification MOS Q4 are connected with the analog ground AGND, the fourth pin of the second synchronous rectification MOS Q4 is connected with the third node G2, and the fifth to eighth pins of the second synchronous rectification MOS Q4 are connected with one end of the second main transformer secondary winding T2-C.

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