CN217904263U

CN217904263U - Adjustable constant-voltage high-frequency switching power supply circuit with wide-range output

Info

Publication number: CN217904263U
Application number: CN202221580296.5U
Authority: CN
Inventors: 张文杰; 张英杰
Original assignee: Shenzhen Feihang Electrical Technology Co ltd
Current assignee: Shenzhen Feihang Electrical Technology Co ltd
Priority date: 2022-06-23
Filing date: 2022-06-23
Publication date: 2022-11-25
Anticipated expiration: 2032-06-23

Abstract

The utility model discloses an adjustable constant voltage high frequency switch power supply circuit with wide-range output, which comprises a main power supply circuit, an auxiliary power supply circuit, a transformer winding switch circuit, an output stage logic circuit and a sampling feedback circuit; the main power circuit is connected with the auxiliary power circuit, the transformer winding switch circuit and the sampling feedback circuit, and the auxiliary power circuit supplies power to the sampling feedback circuit, the main power circuit and the output-stage logic circuit; the transformer winding switch circuit comprises a plurality of winding switch units which are graded according to the output voltage range, the output-level logic circuit comprises a plurality of control units, the sampling feedback circuit controls the corresponding control units to output driving signals by adjusting the reference voltage of the reference point so as to drive the corresponding winding switch units to output the corresponding output voltages, therefore, the required output voltages can be output in a wide range, and the output voltages can be adjusted according to actual conditions, so that the switch power supply circuit is more widely applied and more convenient to use.

Description

Adjustable constant-voltage high-frequency switching power supply circuit with wide-range output

Technical Field

The utility model relates to switching power supply technical field especially involves an adjustable constant voltage high frequency switching power supply circuit of wide range output.

Background

The traditional high-frequency constant-voltage switching power supply is limited by the turn ratio of a transformer, and because the voltage value of a primary circuit of the power supply in any time needs to be smaller than the voltage withstanding value of the DS pole of a main switching tube, the voltage of the DS pole tip of the switching tube is too high and the stress of a rectifier diode is too high when the voltage exceeds the limit, the risk of damage is caused, otherwise, the output is unstable due to insufficient duty ratio when low voltage is input.

At present, the output voltage value of a conventional high-frequency constant-voltage switching power supply can only be adjusted between an upper voltage and a lower voltage by 5V, for example, a high-frequency transformer designed to be 12V can generally output 8V at the lowest and 17V at the highest, the withstand voltage value of the power supply circuit is obtained by multiplying the output voltage Vout by the transformer turn ratio N, adding the input terminal bus voltage Vin 380Vdc and then adding the leakage inductance voltage of the transformer by about 100Vdc, in order to make the withstand voltage value of the power supply circuit smaller than the DS-pole withstand voltage value of the main switching tube, the output voltage value adjustment range is approximately between the upper voltage and the lower voltage by 5V, the output voltage range of the switching power supply is extremely limited, and the use range of the switching power supply is limited, so an adjustable constant-voltage switching power supply circuit with a wider output voltage range is urgently needed.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing an adjustable constant voltage high frequency switching power supply circuit of wide range output aims at solving among the prior art switching power supply's the technical problem of output voltage scope undersize.

Based on the above purpose, the utility model provides an adjustable constant voltage high frequency switch power supply circuit of wide range output, including main power supply circuit, auxiliary power supply circuit, transformer winding switch circuit, output level logic circuit and sampling feedback circuit;

the main power circuit is respectively connected with the auxiliary power circuit, the transformer winding switch circuit and the sampling feedback circuit, the auxiliary power circuit is respectively connected with the sampling feedback circuit and the output stage logic circuit to supply power to the sampling feedback circuit, the main power circuit and the output stage logic circuit, and the transformer winding switch circuit is respectively connected with the sampling feedback circuit and the output stage logic circuit;

the transformer winding switch circuit comprises a plurality of winding switch units which are graded according to output voltage ranges, the output-level logic circuit comprises a plurality of control units corresponding to the winding switch units, and the sampling feedback circuit controls the control units corresponding to the output-level logic circuit to output driving signals by adjusting reference voltage of a reference point so as to drive the corresponding winding switch units to output voltages in corresponding ranges.

Furthermore, the winding switch unit comprises power field effect transistors which are driven to be switched on through driving signals of the output-stage logic circuit, and a grid electrode of each power field effect transistor is connected with a clamping diode.

Further, in the winding switch units classified by the output voltage range, the cathode of the diode of the winding switch unit of the highest classification is connected with a clamping circuit.

Furthermore, the control unit comprises a first comparator, two input end divider resistors, a first diode, two output end divider resistors and a triode;

one input divider resistance one end ground connection, the other end and another input divider resistance connects, another input divider resistance with transformer winding switch circuit, sampling feedback circuit connect, the forward input of first comparator is connected two between the input divider resistance, the reverse input of first comparator is used for the input reference voltage, the output of first comparator is connected the negative pole of first diode, the positive pole of first diode is connected the base of triode, one output divider resistance one end is connected first diode with between the triode, other end ground connection, another output divider resistance one end is connected first diode with between the triode, the other end is connected the collecting electrode of triode, the projecting pole of triode is connected correspondingly winding switch unit.

Further, the auxiliary power supply circuit comprises a first transformer, a first capacitor, a second diode, a third diode, a first inductor and a second inductor;

the two ends of the first transformer are respectively connected with the anodes of the second diode and the third diode, the cathode of the second diode is connected with one end of the first inductor, the cathode of the third diode is connected with one end of the second inductor, the other end of the first inductor is connected with the collector of the triode in the control unit and the output end divider resistor, the other end of the second inductor is connected with the first comparator in the control unit, and the first capacitor and the second capacitor are connected in parallel between the second diode and the first inductor as well as between the third diode and the second inductor; and two ends of the second inductor are connected with a voltage feedback loop circuit, and the voltage feedback loop circuit is connected with the main power supply circuit.

Further, the sampling feedback circuit includes a reference source circuit including a voltage dividing resistor, and the reference voltage is determined by adjusting a voltage value of the voltage dividing resistor.

Further, the sampling feedback circuit comprises an adjustable resistor VR, an operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a fifth resistor, a sixth resistor and a photoelectric coupler, and the divider resistor comprises a first resistor and a second resistor;

the positive input end of the operational amplifier is connected with one end of the second resistor, the other end of the second resistor is connected with a reference source circuit, the first resistor, the third capacitor and the adjustable resistor VR are connected in parallel between the operational amplifier and the second resistor, one ends of the first resistor, the third capacitor and the adjustable resistor VR are grounded, and the other ends of the first resistor and the adjustable resistor VR are connected with a single chip microcomputer;

the transformer winding switching circuit is connected between the third resistor and the operational amplifier, the fourth capacitor and the fifth capacitor are connected between the reverse input end and the output end of the operational amplifier in parallel, the fourth resistor is connected with the fourth capacitor in series, the output end of the operational amplifier is connected with one end of the fifth resistor, the other end of the fifth resistor is connected with one end of the sixth resistor and one pin of one end of the photoelectric coupler, the other end of the sixth resistor is connected with the other pin of one end of the photoelectric coupler and is connected with the auxiliary power circuit and the output stage logic circuit, one pin of the other end of the photoelectric coupler is connected with the main power circuit and is connected with one end of the sixth capacitor, and the other pin is grounded and is connected with the other end of the sixth capacitor.

Further, the voltage dividing resistor is controlled by the adjustable resistor VR to determine the reference voltage of the reference point so as to adjust the output voltage value, or the voltage dividing resistor is controlled by the single chip microcomputer to adjust the reference voltage of the reference point so as to adjust the output voltage value.

The utility model provides an adjustable constant voltage high frequency switch power supply circuit of wide range output, through main power source circuit, auxiliary power source circuit, transformer winding switch circuit, output level logic circuit and sampling feedback circuit cooperation, because transformer winding switch circuit includes a plurality of winding switch units according to the output voltage range is hierarchical, adjust the reference voltage of benchmark point, and then the control unit output drive signal that control output level logic circuit corresponds, with the voltage that the winding switch unit output that the drive corresponds the scope, but wide range ground exports required output voltage like this, and can adjust according to actual conditions, make the application of switching power supply circuit more extensive, it is more convenient to use.

Drawings

Fig. 1 is a circuit diagram of a transformer winding switching circuit in an embodiment of the wide-range output adjustable constant-voltage high-frequency switching power supply circuit of the present invention;

fig. 2 is a circuit diagram of an output stage logic circuit in an embodiment of the wide-range output adjustable constant-voltage high-frequency switching power supply circuit of the present invention;

fig. 3 is a circuit diagram of a reference voltage circuit in an embodiment of the wide-range output adjustable constant-voltage high-frequency switching power supply circuit of the present invention;

fig. 4 is a circuit diagram of an auxiliary power circuit in an embodiment of the wide-range output adjustable constant-voltage high-frequency switching power circuit of the present invention;

fig. 5 is a circuit diagram of a sampling feedback circuit in an embodiment of the adjustable constant voltage high frequency switching power supply circuit with wide output range of the present invention;

fig. 6 is a circuit diagram of a reference source circuit in an embodiment of the wide-range output adjustable constant-voltage high-frequency switching power supply circuit of the present invention;

fig. 7 is a circuit diagram of the main power circuit and part of the auxiliary power circuit in an embodiment of the adjustable constant voltage high frequency switching power supply circuit with wide output range of the present invention.

The objects, features and advantages of the present invention will be further described with reference to the accompanying drawings.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the disclosed embodiments are merely exemplary of the invention, and are not intended to limit the invention to the precise embodiments disclosed. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

It should be noted that all the directional indicators (such as upper, lower, left, right, front, and rear … …) in the embodiments of the present invention are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit ly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions in the embodiments may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1-7, the present invention provides an adjustable constant voltage high frequency switching power supply circuit with wide output range, which comprises a main power circuit, an auxiliary power circuit, a transformer winding switching circuit, an output stage logic circuit and a sampling feedback circuit; the main power circuit comprises a second main power management chip IC2, the main power circuit adopts a circuit structure in the prior art, and reference is made to FIG. 7, which is not described herein in detail, the auxiliary power circuit comprises a first main power management chip IC1, wherein a VCC end pin 5 of the first main power management chip IC1 is connected with the second main power management chip IC2, the main power circuit is respectively connected with the auxiliary power circuit, the transformer winding switch circuit and the sampling feedback circuit, the auxiliary power circuit is respectively connected with the sampling feedback circuit and the output stage logic circuit to supply power to the sampling feedback circuit and the output stage logic circuit, and the auxiliary power circuit supplies power to the second main power management chip IC2 in the main power circuit through a transformer winding T1C, and the transformer winding switch circuit is respectively connected with the sampling feedback circuit and the output stage logic circuit;

the transformer winding switch circuit comprises a plurality of winding switch units which are graded according to output voltage ranges, the range of the output voltage is not limited in the embodiment, the output voltage range required by regulation can be realized by serially connecting the plurality of winding switch units according to actual requirements, correspondingly, the output-stage logic circuit comprises a plurality of control units corresponding to the winding switch units, and the sampling feedback circuit controls the control units corresponding to the output-stage logic circuit to output driving signals by regulating the reference voltage of the reference point so as to drive the corresponding winding switch units to output voltages in the corresponding ranges.

Specifically, when the input is connected with an alternating current commercial power, the auxiliary power supply starts to work, working voltage is provided for a second power management chip and an output stage logic circuit of a main power supply circuit, the main power supply starts to work, the output voltage is the output voltage recognized by which is set in advance, the reference voltage of a reference point in a sampling feedback circuit can be adjusted at the moment, the sampling reference is changed by changing the reference voltage, the output stage logic circuit automatically switches corresponding control units to work in different output voltage sections, and therefore corresponding driving signals are output to drive corresponding winding switch units, and therefore the transformer series connection compatible wide-range output is achieved.

In an embodiment, the sampling feedback circuit includes a reference source circuit, the reference source circuit includes a voltage dividing resistor, the reference voltage of the reference point can be determined by adjusting a resistance value of the voltage dividing resistor, and in addition, the reference voltage can also be adjusted by the single chip microcomputer, for example, the single chip microcomputer outputs an adjustment signal to change a sampling reference and further adjust the output voltage, that is, the single chip microcomputer controls and adjusts the reference voltage of the reference point to adjust the output voltage value, and also can change the resistance value of the voltage dividing resistor by adjusting an adjustable resistor VR connected in parallel with the voltage dividing resistor, thereby determining the reference voltage of the reference point, for example, manually adjusting the resistance value of the adjustable resistor VR to control the voltage value of the voltage dividing resistor, and further change the sampling reference, so that the output voltage is adjusted to be within a designed voltage range.

In one embodiment, in order to ensure that the gate voltage stress of a power effect tube (mos tube) in a transformer winding switching circuit is within a safe range at the time of high output voltage or no load, a clamping diode is designed on the gate of each power effect tube, that is, the gate of each power effect tube is connected with one clamping diode, and the power effect tubes, that is, electronic switching tubes, can be driven to be turned on through the driving information of an output stage logic circuit.

Further, the transformer winding switching circuit in this embodiment is provided with a plurality of winding switching units, each corresponding to a different output voltage range class, for example, 1V-5v,6V-12v,13v-18v,19v-24v,25v-30V, etc., in the plurality of winding switching units classified according to the output voltage range, the cathode of the diode of the winding switching unit in the highest classification is connected with a clamping circuit, for example, in the winding switching unit corresponding to the output voltage range of 25-30V, the cathode of the diode thereof is connected with a clamping circuit.

In one embodiment, referring to fig. 1, the transformer winding switching circuit includes a second transformer T2, a winding a, a winding B, a winding C, a winding D, a winding E, a diode D1, a diode D2, a diode D3, a diode D4, a diode D5, a power effect tube Q1, a power effect tube Q2, a power effect tube Q3, a power effect tube Q4, a clamping diode ZD1, a clamping diode ZD2, a clamping diode ZD3, a clamping diode ZD4, a clamping diode ZD5, and a resistor R20, two ends of the second transformer T2 are respectively connected to an HV end and a QD2 end of a main power circuit, that is, a pin 1 thereof is connected to the HV end, a pin 2 thereof is connected to the QD2 end, a pin 7 of the winding a is grounded, an anode of the diode D1 is connected between the winding a and the winding B, and a cathode of the diode D1 is connected to a source of the power effect tube Q1; the anode of a diode D2 is connected between the winding B and the winding C, the cathode of the diode D2 is connected with the drain electrode of a power effect tube Q1, the grid electrode of the power effect tube Q1 is connected with the cathode of a clamping diode ZD1 and is simultaneously connected with the VG1 end of the output stage logic circuit, and the anode of the diode ZD1 is grounded; the anode of a diode D3 is connected between the winding C and the winding D, the cathode of the diode D3 is connected with the drain electrode of a power effect tube Q2, the source electrode of the power effect tube Q2 is connected with the source electrode of a power effect tube Q1, the grid electrode of the power effect tube Q2 is connected with the cathode of a clamping diode ZD2 and is simultaneously connected with the VG2 end of the output-stage logic circuit, and the anode of the diode ZD2 is grounded; the anode of a diode D4 is connected between the winding D and the winding E, the cathode of the diode D4 is connected with the drain electrode of a power effect tube Q3, the source electrode of the power effect tube Q3 is connected with the source electrode of a power effect tube Q2, the grid electrode of the power effect tube Q3 is connected with the cathode of a clamping diode ZD3 and is simultaneously connected with the VG3 end of the output-stage logic circuit, and the anode of the diode ZD3 is grounded; the pin 13 of the winding E is connected to the anode of the diode D5, the cathode of the diode D5 is connected to the drain of the power effect tube Q4, the source of the power effect tube Q4 is connected to the source of the power effect tube Q3, the source of the power effect tube Q4 is the main output terminal, the source of the power effect tube Q4 is connected in parallel to two capacitors, the other ends of the two capacitors are grounded, the gate of the power effect tube Q4 is connected to the cathode of the clamping diode ZD4, and is connected to the VG4 end of the output stage logic circuit, the anode of the diode ZD4 is grounded, the cathode of the clamping diode 5 is connected between the diode D5 and the power effect tube Q4, the anode of the clamping diode ZD5 is connected to one end of the resistor R20, and the other end of the resistor R20 is grounded, in this embodiment, the output voltage range corresponding to the winding a is 1V-5V, the output unit range corresponding to the winding B is 6V-12V, the output unit range corresponding to the winding C is 13V-18V, the output unit range corresponding to the winding D is 19V-24V, and the output unit range corresponding to the winding E is 25V-30V.

The winding A and the diode D1 form the winding switch unit, or the winding B, the diode D2, the power effect tube Q1 and the clamping diode ZD1 form the winding switch unit, and so on, a plurality of winding switch units can be arranged; the clamp diode ZD5 and the resistor R20 constitute the clamp circuit.

In one embodiment, the control unit includes a first comparator, two input end voltage dividing resistors, a first diode, two output end voltage dividing resistors, and a triode; wherein, an input divider resistance one end ground connection, the other end is connected with another input divider resistance, another input divider resistance is connected with above-mentioned main output, the forward input of first comparator is connected between two input divider resistances, the reverse input of first comparator is used for the input reference voltage, the negative pole of first diode is connected to the output of first comparator, the base of triode is connected to the positive pole of first diode, an output divider resistance one end is connected between first diode and the triode, other end ground connection, another output divider resistance one end is connected between first diode and triode, the collecting electrode of triode is connected to the other end, the corresponding winding switch unit is connected to the projecting pole of triode.

In an embodiment, referring to fig. 2, the output stage logic circuit includes four control units and a reference voltage circuit, specifically, the first control unit includes a first comparator U2D, an input terminal divider resistor R14, an input terminal divider resistor R13, a first diode D6, an output terminal divider resistor R16, an output terminal divider resistor R15 and a transistor Q5, one end of the input terminal divider resistor R14 is grounded, the other end is connected to one end of the input terminal divider resistor R13, the other end of the input terminal divider resistor R13 is connected to a source main output terminal of the power effect transistor Q4, a forward input terminal of the first comparator U2D is connected between the input terminal divider resistor R14 and the input terminal divider resistor R13, a reverse input terminal of the first comparator U2D is used for inputting the reference voltage, an output terminal of the first comparator U2D is connected to a negative electrode of the first diode D6, a transistor of the first diode D6 is connected to a base electrode of the transistor Q5, one end of the output terminal divider resistor R16 is connected between the first diode D6 and the transistor Q5, the other end is grounded, a collector electrode of the transistor Q5 is connected to an emitter electrode of the transistor Q1.

The second control unit comprises a first comparator U2C, an input end divider resistor R10, an input end divider resistor R9, a first diode D7, an output end divider resistor R12, an output end divider resistor R11 and a triode Q6, one end of the input end divider resistor R10 is grounded, the other end is connected with one end of the input end divider resistor R9, the other end of the input end divider resistor R9 is connected with a source electrode main output end of the power effect tube Q4, a forward input end of the first comparator U2C is connected between the input end divider resistor R10 and the input end divider resistor R9, a reverse input end of the first comparator U2C is used for inputting reference voltage, an output end of the first comparator U2C is connected with a negative electrode of the first diode D7, a positive electrode of the first diode D7 is connected with a base electrode of the triode Q6, one end of the output end divider resistor R12 is connected between the first diode D7 and the triode Q6, the other end is grounded, one end of the output end divider resistor R11 is connected between the first diode D7 and the triode Q6, the other end is connected with a collector electrode of the triode Q2, and a grid electrode of the triode Q2 is connected with a grid electrode of the power effect tube Q2.

The first control unit comprises a first comparator U2B, an input end divider resistor R6, an input end divider resistor R5, a first diode D8, an output end divider resistor R7 and a triode Q7, one end of the input end divider resistor R6 is grounded, the other end of the input end divider resistor R5 is connected with one end of the input end divider resistor R5, one end of the input end divider resistor R5 is connected with a source electrode main output end of the power effect tube Q4, a forward input end of the first comparator U2B is connected between the input end divider resistor R6 and the input end divider resistor R5, a reverse input end of the first comparator U2B is used for inputting reference voltage, an output end of the first comparator U2B is connected with a negative electrode of the first diode D8, an anode of the first diode D8 is connected with a base electrode of the triode Q7, one end of the output end divider resistor R8 is connected between the first diode D8 and the triode Q7, the other end of the output end divider resistor R7 is grounded, one end of the first diode D8 is connected between the first diode D8 and the triode Q7, the other end of the triode Q7 is connected with a collector electrode of the triode Q7, and a grid electrode of the divider VG3 of the power effect tube Q3.

The fourth control unit comprises a first comparator U2A, an input end divider resistor R2, an input end divider resistor R1, a first diode D9, an output end divider resistor R4, an output end divider resistor R3 and a triode Q8, one end of the input end divider resistor R2 is grounded, the other end is connected with one end of the input end divider resistor R1, the other end of the input end divider resistor R1 is connected with a source electrode main output end of the power effect tube Q4, a forward input end of the first comparator U2A is connected between the input end divider resistor R1 and the input end divider resistor R2, a reverse input end of the first comparator U2A is used for inputting reference voltage, an output end of the first comparator U2A is connected with a negative electrode of the first diode D9, a positive electrode of the first diode D9 is connected with a base electrode of the triode Q8, one end of the output end divider resistor R4 is connected between the first diode D9 and the triode Q8, the other end is grounded, one end of the output end divider resistor R3 is connected between the first diode D9 and the triode Q8, the other end is connected with a grid electrode of the triode Q4, and a grid electrode of the power effect tube Q4 is connected with a grid electrode of the triode Q8.

Referring to fig. 3, the reference voltage circuit includes a capacitor C100, a resistor R100, and a diode D100, an anode of the diode D100 is grounded, a cathode of the diode D100 is connected to one end of the resistor R100, one end of the capacitor C100 is connected to an anode of the diode D100, and the other end of the capacitor C100 is connected between the diode D100 and the resistor R100, and is connected to the inverting input terminals of the first comparator U2D, the first comparator U2C, the first comparator U2B, and the first comparator U2A.

It should be noted that the different output voltage step ranges can be determined by the output voltage dividing resistors, i.e. the output voltage value depends on the two output voltage dividing resistors of the base of the transistor in the control unit.

In one embodiment, referring to fig. 4, the auxiliary power circuit includes a first transformer T1, a first capacitor C1, a second capacitor C2, a second diode D10, a third diode D11, a first inductor L1, and a second inductor L2; the two ends of the first transformer T1 are respectively connected to a second diode D10 and an anode D11 of a third diode, the cathode of the second diode D10 is connected to one end of a first inductor L1, the cathode of the third diode D11 is connected to one end of a second inductor L2, the other end of the first inductor L1 is connected to the collector of the triode in the control unit and the output-end divider resistor, for example, the other end of the first inductor L1 is connected to the collector of the triode Q5 and the output-end divider resistor R15 in the first control unit, the collector of the triode Q6 and the output-end divider resistor R11 in the second control unit, the collector of the triode Q7 and the output-end divider resistor R7 in the third control unit, and the collector of the triode Q8 and the output-end divider resistor R3 in the fourth control unit; the other end of the second inductor L2 is connected to the first comparator in the control unit, for example, the other end of the second inductor L2 is connected to the first comparator U2D in the first control unit, the first comparator U2C in the second control unit, the first comparator U2B in the third control unit, and the first comparator U2A in the fourth control unit; the first capacitor C1 and the second capacitor C2 are connected in parallel between the second diode D10 and the first inductor L1, and between the third diode D11 and the second inductor L2; and a voltage feedback loop circuit is connected to two ends of the second inductor L2 and is connected to a main power management chip FB1 end in the auxiliary power circuit, and further, a capacitor C7 is further arranged, and the capacitor C7 is connected between the first inductor L1 and the second inductor L2.

The voltage feedback loop circuit comprises a photocoupler OC2, a capacitor C7, a capacitor C8, a diode D12, a resistor R33, a resistor R34, a resistor R35, a resistor R36, a resistor R37 and a resistor R38, a pin 3 of the photocoupler OC2 is connected with an FB1 end of the main power supply circuit and one end of the capacitor C7 is connected, the other end of the capacitor C7 is grounded and is connected with a pin 4 of the photocoupler OC2, a pin 1 of the photocoupler OC2 is respectively connected with one ends of the resistor R33 and the resistor R38, the other end of the resistor R33 is connected between the first capacitor C1 and the second capacitor C2, the other end of the resistor R38 is connected with a cathode of the diode D12 and one end of the capacitor C8, an anode of the diode D12 is grounded, the other end of the capacitor C8 is respectively connected with the resistor R35, the resistor R34, the resistor R36, one end of the resistor R37 and the diode D12, the other end of the resistor R35 is connected with one end of the first inductor L1, the second inductor L2, and the other end of the resistor R36 and the resistor R37 are grounded.

It should be noted that, when the other end of the first inductor L1 is connected to the collector of the triode in the control unit and the output end voltage-dividing resistor, the voltage thereof exceeds the highest output voltage value of the circuit, usually exceeds 10V, in this embodiment, the winding switch unit corresponds to the highest output voltage value of 30V, at this time, the voltage of the other end of the first inductor L1 may be 42V, when a winding switch unit is added, and the highest output voltage can reach 40V, the voltage of the other end of the first inductor L1 may be 52V, and so on, the voltage setting here is 10V more than the highest output voltage value, so as to ensure the normal operation of the circuit.

In one embodiment, referring to fig. 5, the sampling feedback circuit further includes an operational amplifier U1A, a first resistor R21, a second resistor R22, a third resistor R23, a fourth resistor R24, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a fifth resistor R25, a sixth resistor R26, and a photocoupler OC1; the first resistor R21 and the second resistor R22 are the voltage dividing resistors, the forward input end of the operational amplifier U1A is connected with one end of the second resistor R22, the other end of the second resistor R22 is connected with the reference source circuit, the first resistor R21, the third capacitor C3 and the adjustable resistor VR are connected between the operational amplifier U1A and the second resistor R22 in parallel, the connection point between the first resistor R21 and the second resistor R22 is the reference point, one ends of the first resistor R21, the third capacitor C3 and the adjustable resistor VR are grounded, the other ends of the first resistor R21 and the adjustable resistor VR are connected with the single chip microcomputer, the reference voltage of the reference point can be adjusted through the single chip microcomputer, or the resistance values of the adjustable resistor VR are adjusted to change the resistance values of the first resistor R21 and the second resistor R22, namely the voltage of the first resistor R21 and the second resistor R22, so as to change the reference voltage of the reference point; the inverting input end of the operational amplifier U1A is connected to one end of a third resistor R23, the other end of the third resistor R23 is grounded, one end of a resistor R27 is connected between the third resistor R23 and the operational amplifier U1A, the other end of the resistor R27 is connected to the main output end of the transformer winding switching circuit, the third resistor R23 and the resistor R27 are sampling resistors of a sampling feedback circuit, a fourth capacitor C4 and a fifth capacitor C5 are connected in parallel between the inverting input end and the output end of the operational amplifier U1A, a fourth resistor R24 is connected in series with the fourth capacitor C4, the output end of the operational amplifier U1A is connected to one end of a fifth resistor R25, the other end of the fifth resistor R25 is connected to one end of a sixth resistor R26 and one pin 1 at one end of an opto-coupler OC1, the other end of the sixth resistor R26 is connected to the other pin 2 at one end of the opto-coupler OC1, and is connected to an auxiliary power supply circuit (such as a second inductor L2 in the auxiliary power supply circuit) and an output stage logic circuit, one end of the other end of the opto-coupler OC1 is connected to the main power supply management chip FB 3 at the other end of the first resistor FB1, and is connected to the other end of the sixth capacitor C6, and is connected to the other end of the capacitor C6, and connected to the other end of the capacitor C6.

Referring to fig. 6, the reference source circuit includes a resistor R210, a resistor R220, a resistor R230, a diode D200, a transistor Q200, and a capacitor C200, wherein one end of the resistor R210 is connected to one end of the resistor R220, the other end of the resistor R210 is connected to an anode of the diode D200 and one end of the capacitor C200, respectively, and is grounded, the other end of the resistor R220 is connected to one end of the resistor R230 and a collector of the transistor Q200, and is connected to a second inductor L2, a sampling feedback circuit, and an output stage logic circuit in the auxiliary power circuit, the other end of the resistor R230 is connected to a cathode of the diode D200 and a base of the transistor Q200, and an emitter of the transistor Q200 is connected to the other end of the capacitor C200, and is connected to a positive input terminal of an operational amplifier U1A of the sampling feedback circuit, or connected to a second resistor R22.

For example, initially accepts an output voltage of 5V, at this time, the input voltage dividing resistor R1 and the input voltage dividing resistor R2 at the positive input end of the first comparator U2A, the input voltage dividing resistor R5 and the input voltage dividing resistor R6 of the first comparator U2B, the input voltage dividing resistor R9 and the input voltage dividing resistor R10 of the first comparator U2C, and the values of the input voltage dividing resistor R13 and the input voltage dividing resistor R14 of the first comparator U2D determine that all four control units output low levels, so that no driving signal is sent from the power effect transistor Q1 to the power effect transistor Q4 in the transformer winding switching circuit, and only the winding a in the transformer winding switching circuit operates. In order to suppress the power effect transistor from having too high voltage stress when operating at low output voltage, the above-mentioned clamp circuit is added in this embodiment, and the value of the clamp circuit is properly higher than the normal output voltage value, so that the clamp circuit does not work when the power effect transistor Q4 is turned on to output the highest voltage. In order to ensure that the voltage stress of the gates of the power effect transistor Q1 and the power effect transistor Q4 is within a safe range at a high output voltage or during no load, the present embodiment correspondingly designs the clamping diode ZD1 and the clamping diode ZD4 on the gates of the power effect transistor Q1 and the power effect transistor Q4, respectively.

When the output voltage needs to be adjusted and improved, the adjustable resistor VR in the sampling feedback circuit can be adjusted in the forward direction, at this time, the reference voltage of the pin 3 of the forward input end of the operational amplifier U1A rises, the output voltage of the operational amplifier U1A rises along with the reference voltage, the voltage feedback loop current in the second voltage feedback circuit is reduced, the PWM duty ratio is increased, and the output voltage rises along with the voltage feedback loop current. When the output voltage exceeds 5V, the voltage of the forward input end of the first comparator U2D exceeds the reference voltage of the reverse input end, at the moment, the first comparator U2D outputs a high level, the triode Q5 outputs a high level, and the output voltage value depends on the output end divider resistor R15 and the output end divider resistor R16 of the base electrode of the triode Q5, so that the power effect tube Q1 of the transformer winding switching circuit is driven to be switched on, the winding A and the winding B work in series, and the output condition of 6-12V is met.

And continuously adjusting the adjustable resistor VR in the sampling feedback circuit in the forward direction, wherein the reference voltage of the pin 3 of the forward input end of the operational amplifier U1A is further increased, the output voltage of the operational amplifier U1A is further increased in proportion, the current of the voltage feedback loop is further reduced, the PWM duty ratio is further increased, and the output voltage is further increased. When the output voltage exceeds 12V, the voltage of the forward input end of the first comparator U2C exceeds the reference voltage of the reverse input, the first comparator U2C outputs a high level, the triode Q6 outputs a high level, the output voltage value depends on the resistance values of the output end divider resistor R11 and the output end divider resistor R12 of the base electrode of the triode Q6, the power effect tube Q2 of the transformer winding switching circuit is driven to be switched on, the winding A, the winding B and the winding C are connected in series to work, the 13V-18V working condition is met, and meanwhile, as the output voltage exceeds 12V, the power effect tube Q1, the diode D1 and the diode D2 are reversely biased to be switched off. And so on until the output voltage reaches the highest design value, and vice versa.

In addition, the reference voltage of the pin 3 of the forward input end of the operational amplifier U1A is reduced by continuously and reversely adjusting the adjustable resistor VR in the sampling feedback circuit, so that the output voltage of the operational amplifier U2A is reduced, the current of the voltage feedback loop is increased, and the PWM duty ratio is reduced until the output voltage is reduced to 1V.

Therefore, the required output voltage can be output in a wide range by the mode, and the adjustment can be carried out according to the actual situation, so that the switching power supply circuit is wider in application and more convenient to use.

The above only is the preferred embodiment of the present invention, and the patent scope of the present invention is not limited thereby, and all the equivalent structures or equivalent processes made by the contents of the specification and the drawings are utilized, or directly or indirectly applied to other related technical fields, and all the same principles are included in the patent protection scope of the present invention.

Claims

1. An adjustable constant-voltage high-frequency switching power supply circuit with wide-range output is characterized by comprising a main power supply circuit, an auxiliary power supply circuit, a transformer winding switching circuit, an output-stage logic circuit and a sampling feedback circuit;

the main power circuit is respectively connected with the auxiliary power circuit, the transformer winding switch circuit and the sampling feedback circuit, the auxiliary power circuit is respectively connected with the sampling feedback circuit and the output stage logic circuit and supplies power to the sampling feedback circuit, the main power circuit and the output stage logic circuit, and the transformer winding switch circuit is respectively connected with the sampling feedback circuit and the output stage logic circuit;

2. The wide-range output adjustable constant-voltage high-frequency switching power supply circuit according to claim 1, wherein the winding switching unit includes power fets driven to be turned on by a driving signal of the output stage logic circuit, and a gate of each power fet is connected to a clamping diode.

3. The adjustable constant-voltage high-frequency switching power supply circuit with wide-range output according to claim 1, wherein in a plurality of said winding switch units classified by output voltage range, a clamping circuit is connected to a cathode of a diode of a winding switch unit of the highest classification.

4. The wide-range output adjustable constant-voltage high-frequency switching power supply circuit according to claim 1, wherein the control unit includes a first comparator, two input-end voltage dividing resistors, a first diode, two output-end voltage dividing resistors, and a triode;

5. The wide-range output adjustable constant-voltage high-frequency switching power supply circuit according to claim 4, wherein the auxiliary power supply circuit includes a first transformer, a first capacitor, a second diode, a third diode, a first inductor, and a second inductor;

6. The wide-range output adjustable constant-voltage high-frequency switching power supply circuit according to claim 1, wherein the sampling feedback circuit includes a reference source circuit including a voltage dividing resistor, and the reference voltage is determined by adjusting a voltage value of the voltage dividing resistor.

7. The wide-range output adjustable constant-voltage high-frequency switching power supply circuit according to claim 6, wherein the sampling feedback circuit includes an adjustable resistor VR, an operational amplifier, a third resistor, a fourth resistor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a fifth resistor, a sixth resistor, and a photocoupler, and the voltage dividing resistor includes a first resistor and a second resistor;

the reverse input end of the operational amplifier is connected with one end of a third resistor, the other end of the third resistor is grounded, the transformer winding switch circuit is connected between the third resistor and the operational amplifier, the fourth capacitor and the fifth capacitor are connected between the reverse input end and the output end of the operational amplifier in parallel, the fourth resistor and the fourth capacitor are connected in series, the output end of the operational amplifier is connected with one end of the fifth resistor, the other end of the fifth resistor is connected with one end of the sixth resistor and one pin of one end of the photoelectric coupler, the other end of the sixth resistor is connected with the other pin of one end of the photoelectric coupler, the auxiliary power circuit and the output-stage logic circuit are connected, one pin of the other end of the photoelectric coupler is connected with the main power circuit and one end of the sixth capacitor, and the other pin is grounded and is connected with the other end of the sixth capacitor.

8. The adjustable constant-voltage high-frequency switching power supply circuit with wide-range output as claimed in claim 7, wherein said voltage dividing resistor is controlled by said adjustable resistor VR to determine a resistance value to determine a reference voltage of said reference point to adjust an output voltage value, or is controlled by a single chip microcomputer to adjust a reference voltage of said reference point to adjust an output voltage value.