CN221688507U - Step-down circuit and switching power supply - Google Patents
Step-down circuit and switching power supply Download PDFInfo
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- CN221688507U CN221688507U CN202322837642.4U CN202322837642U CN221688507U CN 221688507 U CN221688507 U CN 221688507U CN 202322837642 U CN202322837642 U CN 202322837642U CN 221688507 U CN221688507 U CN 221688507U
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- optocoupler
- adjustable shunt
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- 230000000694 effects Effects 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 2
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- 230000009286 beneficial effect Effects 0.000 description 1
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- 238000000034 method Methods 0.000 description 1
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Abstract
The utility model discloses a voltage reducing circuit and a switching power supply, wherein the voltage reducing circuit comprises a feedback module and a control module, and the feedback module is connected with the control module; the feedback module comprises a three-terminal adjustable shunt reference voltage source, a first resistor, a second resistor and a third resistor, wherein a reference end of the three-terminal adjustable shunt reference voltage source is connected to a voltage output end through the first resistor, the reference end of the three-terminal adjustable shunt reference voltage source is also connected to a power ground through the second resistor, an anode of the three-terminal adjustable shunt reference voltage source is connected to the power ground through the third resistor, and an anode of the three-terminal adjustable shunt reference voltage source is connected to a signal ground. According to the utility model, the third resistor is introduced into the feedback module and connected between the three-terminal adjustable shunt reference voltage source and the power supply ground, so that the output voltage can be reduced, the problem of power supply overpower use caused by larger current required by output is avoided, and the active voltage reduction effect of the output voltage is effectively realized.
Description
Technical Field
The utility model belongs to the field of switching power supplies, and particularly relates to a voltage reduction circuit and a switching power supply.
Background
Switching power supplies currently exhibit a trend toward high efficiency, high power density, and multiple applications. For places requiring large current for output, in some special application places, especially places requiring larger current for output and places requiring no particularly high voltage for output, when the current for output exceeds the rated current, reliability risks are easily caused by over-high power, and the service life of the power supply is influenced.
Disclosure of Invention
In view of the above, the present utility model is directed to a voltage reduction circuit and a switching power supply, which can actively reduce the output voltage, thereby reducing the power.
In order to achieve the above purpose, the present utility model adopts the following technical scheme:
In a first aspect, the utility model provides a voltage reduction circuit, which comprises a feedback module and a control module, wherein the feedback module is connected with the control module;
the feedback module comprises a three-terminal adjustable shunt reference voltage source, a first resistor, a second resistor and a third resistor, wherein the cathode of the three-terminal adjustable shunt reference voltage source is connected to a voltage input end, the cathode of the three-terminal adjustable shunt reference voltage source is connected to the reference end of the three-terminal adjustable shunt reference voltage source through the control module, the reference end of the three-terminal adjustable shunt reference voltage source is connected to a voltage output end through the first resistor, the reference end of the three-terminal adjustable shunt reference voltage source is also connected to a power ground through the second resistor, the anode of the three-terminal adjustable shunt reference voltage source is connected to the power ground through the third resistor, and the anode of the three-terminal adjustable shunt reference voltage source is connected to a signal ground.
Further, the control module comprises a fourth resistor, a first capacitor and a second capacitor, wherein the first end of the fourth resistor is connected to the cathode of the three-terminal adjustable shunt reference voltage source, the second end of the fourth resistor is connected to the reference end of the three-terminal adjustable shunt reference voltage source through the second capacitor, and the cathode of the three-terminal adjustable shunt reference voltage source is connected to the reference end of the three-terminal adjustable shunt reference voltage source through the first capacitor.
Further, the step-down circuit further comprises an optocoupler circuit module connected between the cathode of the three-terminal adjustable shunt reference voltage source and the voltage input end, wherein a first input end of the optocoupler circuit module is connected to the voltage input end, and a second input end of the optocoupler circuit module is connected to the cathode of the three-terminal adjustable shunt reference voltage source.
Further, the optocoupler circuit module comprises a fifth resistor, a sixth resistor, a seventh resistor and an optocoupler, wherein the anode of an optocoupler diode of the optocoupler is connected to the voltage input end through the sixth resistor, the anode of the optocoupler diode of the optocoupler is connected to the cathode of the optocoupler diode of the optocoupler through the seventh resistor, the cathode of the optocoupler diode of the optocoupler is connected to the cathode of the three-terminal adjustable shunt reference voltage source, the collector of an optocoupler triode of the optocoupler is connected to the feedback end through the fifth resistor, and the emitter of the optocoupler triode of the optocoupler is connected to analog ground.
In a second aspect, the present utility model provides a switching power supply comprising a step-down circuit as described in the first aspect.
Compared with the prior art, the utility model has the following beneficial effects:
According to the utility model, the third resistor is introduced into the feedback module and connected between the three-terminal adjustable shunt reference voltage source and the power supply ground, so that the output voltage can be reduced, the problem of power supply overpower use caused by larger current required by output is avoided, and the active voltage reduction effect of the output voltage is effectively realized. The circuit is simple in structure and easy to realize, and can effectively reduce the production cost.
Drawings
FIG. 1 is a schematic diagram of a step-down circuit according to the present utility model;
Fig. 2 is a schematic diagram of an application circuit of an embodiment of a voltage step-down circuit according to the present utility model.
Detailed Description
The present utility model will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present utility model more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.
Referring to fig. 1, the embodiment of the utility model provides a voltage reducing circuit, which includes a feedback module 100 and a control module 200, wherein the feedback module 100 is connected with the control module 200;
The feedback module 100 includes a three-terminal adjustable shunt reference voltage source U1, a first resistor R1, a second resistor R2, and a third resistor, where a cathode of the three-terminal adjustable shunt reference voltage source U1 is connected to a voltage input terminal, a cathode of the three-terminal adjustable shunt reference voltage source U1 is connected to a reference terminal of the three-terminal adjustable shunt reference voltage source U1 through the control module 200, the reference terminal of the three-terminal adjustable shunt reference voltage source U1 is connected to a voltage output terminal through the first resistor R1, the reference terminal of the three-terminal adjustable shunt reference voltage source U1 is also connected to a power ground GND through the second resistor R2, an anode of the three-terminal adjustable shunt reference voltage source U1 is connected to the power ground GND through the third resistor, and an anode of the three-terminal adjustable shunt reference voltage source U1 is connected to the signal ground SGND.
In this embodiment, let Vo be the output voltage; the first resistor R1 and the second resistor R2 are respectively feedback pull-up and pull-down resistors, and Vref is the reference voltage of the three-terminal adjustable shunt reference voltage source U1; when the third resistor is not set, R3 is set as a 0Ω resistor;
Then: vo=vref (R1+R2) (1)/(R2)
Setting Vo as an output voltage; io is the output current; the first resistor R1 and the second resistor R2 are respectively feedback pull-up resistors and pull-down resistors; v R2 is the voltage across the second resistor R2; after the third resistor is arranged, vx is the voltage at two ends of the third resistor R3, and since two ends of the third resistor R3 are respectively connected with GND and SGND, the actual current flow direction is as follows: GND flows to SGND, when the current on the third resistor R3 is-Io; vref is the reference voltage for the control IC; then:
(1)R3＊(-Io)＝-Vx；
(1)VR2+Vx＝Vref；
(2)VR2＝Vref-Vx；
(3)Vo＝R1*(Vref-Vx)/R2+Vref；
(4)Vo＝Vref*(R1+R2)/R2-Vx*R1/R2；
Finally, the method comprises the following steps: vo=vref (r1+r2)/R2-R3 Io R1/R2) -2;
the above calculation can be used to determine that after the negative end GND of the output terminal and the output feedback pull-down resistor are connected to the two ends of the third resistor R3 introduced by the connection of the a pole of the three-terminal adjustable shunt reference voltage source U1, the above calculation formulas (1) and (2) can be compared with the output voltage Vo, and the output voltage Vo is reduced by the voltage R3 x Io x R1/R2. In this embodiment, when the output load current increases, the line loss increases, and the output voltage can be correspondingly reduced, so that the problem of power supply overpower use caused by the need of larger output current is solved, and the active voltage reduction effect of the output voltage is effectively achieved. In this embodiment, the first resistor R1 and the second resistor R2 can adjust resistance values according to different output voltages, and the third resistor R3 can adjust resistance values according to different impedances of lines and output required currents, so that the output voltage can be adjusted.
In an embodiment, the control module 200 includes a fourth resistor R4, a first capacitor C1 and a second capacitor C2, wherein a first end of the fourth resistor R4 is connected to the cathode of the three-terminal adjustable shunt reference voltage source U1, a second end of the fourth resistor R4 is connected to the reference end of the three-terminal adjustable shunt reference voltage source U1 through the second capacitor C2, and the cathode of the three-terminal adjustable shunt reference voltage source U1 is connected to the reference end of the three-terminal adjustable shunt reference voltage source U1 through the first capacitor C1.
In this embodiment, the control module 200 is composed of a first capacitor C1, a second capacitor C2 and a fourth resistor R4, and the stability, accuracy and rapidity of the output can be adjusted by adjusting the first capacitor C1 and the second capacitor C2 of the loop.
In an embodiment, the step-down circuit further includes an optocoupler circuit module 300 connected between the cathode of the three-terminal adjustable shunt reference voltage source U1 and the voltage input terminal, wherein a first input terminal of the optocoupler circuit module 300 is connected to the voltage input terminal, and a second input terminal of the optocoupler circuit module 300 is connected to the cathode of the three-terminal adjustable shunt reference voltage source U1.
In this embodiment, the optocoupler circuit module 300 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and an optocoupler OP1, wherein an anode of an optocoupler diode of the optocoupler OP1 is connected to the voltage input terminal through the sixth resistor R6, an anode of the optocoupler diode of the optocoupler OP1 is connected to a cathode of the optocoupler diode of the optocoupler OP1 through the seventh resistor R7, a cathode of the optocoupler diode of the optocoupler OP1 is connected to a cathode of the three-terminal adjustable shunt reference voltage source U1, a collector of an optocoupler triode of the optocoupler OP1 is connected to the feedback terminal through the fifth resistor R5, and an emitter of the optocoupler triode of the optocoupler OP1 is connected to the analog ground AGND.
In this embodiment, the feedback terminal FB is a feedback signal pin of the control IC, and different control signals are sent out through IC control by feeding back different feedback signals, so as to control the transformer T1, as shown in fig. 2, to affect the voltage input terminal Vo1, so as to obtain different input voltages.
In addition, the embodiment of the utility model also provides a switching power supply, which comprises the step-down circuit.
The above description is not intended to limit the utility model to the particular embodiments disclosed, but to enable any person skilled in the art to make variations, alterations, additions or substitutions within the spirit and scope of the utility model as disclosed.
Claims (5)
1. A voltage step-down circuit, characterized by: the voltage reduction circuit comprises a feedback module and a control module, and the feedback module is connected with the control module;
the feedback module comprises a three-terminal adjustable shunt reference voltage source, a first resistor, a second resistor and a third resistor, wherein the cathode of the three-terminal adjustable shunt reference voltage source is connected to a voltage input end, the cathode of the three-terminal adjustable shunt reference voltage source is connected to the reference end of the three-terminal adjustable shunt reference voltage source through the control module, the reference end of the three-terminal adjustable shunt reference voltage source is connected to a voltage output end through the first resistor, the reference end of the three-terminal adjustable shunt reference voltage source is also connected to a power ground through the second resistor, the anode of the three-terminal adjustable shunt reference voltage source is connected to the power ground through the third resistor, and the anode of the three-terminal adjustable shunt reference voltage source is connected to a signal ground.
2. The buck circuit according to claim 1, wherein the control module includes a fourth resistor, a first capacitor, and a second capacitor, a first end of the fourth resistor being connected to the cathode of the three-terminal adjustable shunt reference voltage source, a second end of the fourth resistor being connected to the reference end of the three-terminal adjustable shunt reference voltage source through the second capacitor, and a cathode of the three-terminal adjustable shunt reference voltage source being connected to the reference end of the three-terminal adjustable shunt reference voltage source through the first capacitor.
3. The voltage reduction circuit according to claim 1, further comprising an optocoupler circuit module connected between the cathode of the three-terminal adjustable shunt reference voltage source and the voltage input terminal, a first input terminal of the optocoupler circuit module being connected to the voltage input terminal, a second input terminal of the optocoupler circuit module being connected to the cathode of the three-terminal adjustable shunt reference voltage source.
4. The voltage reduction circuit according to claim 3, wherein the optocoupler circuit module comprises a fifth resistor, a sixth resistor, a seventh resistor and an optocoupler, wherein an anode of an optocoupler diode of the optocoupler is connected to a voltage input terminal through the sixth resistor, an anode of the optocoupler diode of the optocoupler is connected to a cathode of the optocoupler diode of the optocoupler through the seventh resistor, a cathode of the optocoupler diode of the optocoupler is connected to a cathode of the three-terminal adjustable shunt reference voltage source, a collector of an optocoupler triode of the optocoupler is connected to a feedback terminal through the fifth resistor, and an emitter of the optocoupler triode of the optocoupler is connected to analog ground.
5. A switching power supply comprising a step-down circuit as claimed in any one of claims 1 to 4.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322837642.4U CN221688507U (en) | 2023-10-20 | 2023-10-20 | Step-down circuit and switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322837642.4U CN221688507U (en) | 2023-10-20 | 2023-10-20 | Step-down circuit and switching power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN221688507U true CN221688507U (en) | 2024-09-10 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202322837642.4U Active CN221688507U (en) | 2023-10-20 | 2023-10-20 | Step-down circuit and switching power supply |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN221688507U (en) |
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2023
- 2023-10-20 CN CN202322837642.4U patent/CN221688507U/en active Active
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