A switching power supply circuit

Abstract

The utility model specifically relates to a switching power supply circuit, including a rectifier bridge D1 and a first transformer T1, the rectifier bridge D1 is connected to the input end of the transformer T1, the output end of the first transformer T1 is connected to a high-frequency low-resistance circuit, the output end of the high-frequency low-resistance circuit is connected to a VOUT end, a fifth polyester capacitor C5, a seventeenth resistor R17 and a thirteenth resistor R13 are arranged between the first foot 1 of the first transformer T1 and the output of the rectifier bridge D1, the fifth diode D5 is also connected to the second foot of the first transformer T1, the input end of the first transformer T1 is connected to a detection chip U1, the detection chip U1 is connected to an optocoupler U2, and the optocoupler U2 is also connected to the high-frequency low-resistance circuit. The beneficial effect of the utility model is that the fifth polyester capacitor C5, the seventeenth resistor R17 and the thirteenth resistor R13 are arranged between the first foot 1 of the first transformer T1 and the output of the rectifier bridge D1, the energy of a single pulse input to the first transformer T1 is reduced, the primary current change speed is reduced, and the noise can be further reduced.

Description

Technical Field

[0001] The utility model specifically relates to a switching power supply circuit. Background Art

[0002] An invention application with application number: CN201410822779.5, the name of which is: a switching power supply circuit, the circuit is disclosed as: a rectifier bridge, a first capacitor, a first diode, an inductor, a flyback circuit and a second capacitor, the rectifier bridge has a positive output end and a negative output end, the first capacitor is connected in parallel between the positive output end and the negative output end of the rectifier bridge; the primary circuit of the flyback circuit includes a primary winding of a transformer, a first switch tube and a driving module for driving the first switch tube, and also includes clamping the anode of the first diode at the negative output potential of the rectifier bridge The clamping circuit of the switching power supply circuit is specifically connected as follows: the positive output end of the rectifier bridge is connected to one end of the inductor, the other end of the inductor is connected to the anode of the first diode, the cathode of the first diode is respectively connected to one end of the second capacitor and the drain of the first switch tube, the source of the first switch tube is connected to the same-name end of the primary winding, and the opposite-name end of the primary winding is connected to the other end of the second capacitor; the same-name end of the primary winding is also connected to the negative output end of the rectifier bridge; the anode of the first diode is also connected to the clamping circuit, and the other end of the clamping circuit is connected to the negative output end of the rectifier bridge.

[0003] Noise often occurs during power supply operation. Some of the reasons are process problems with the transformer, such as poor oil immersion, which causes resonance inside the transformer; or other reasons are frequency vibrations initiated by the device itself. Summary of the invention

[0004] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the utility model is to provide a switching power supply circuit that can further reduce noise.

[0005] A switching power supply circuit according to the utility model includes a rectifier bridge D1 and a first transformer T1, the rectifier bridge D1 is connected to the input end of the transformer T1, the output end of the first transformer T1 is connected to a high-frequency low-resistance circuit, the output end of the high-frequency low-resistance circuit is connected to a VOUT end, a fifth polyester capacitor C5, a seventeenth resistor R17 and a thirteenth resistor R13 are arranged between pin 1 of the first transformer T1 and the output of the rectifier bridge D1, the fifth polyester capacitor C5, the seventeenth resistor R17 and the thirteenth resistor R13 are connected in parallel, a fifth diode D5 is connected to a common end between the fifth polyester capacitor C5, the seventeenth resistor R17 and the thirteenth resistor R13, the fifth diode D5 is also connected to pin 2 of the first transformer T1, the input end of the first transformer T1 is connected to a detection chip U1, the detection chip U1 is connected to a photocoupler U2, and the photocoupler U2 is also connected to the high-frequency low-resistance circuit.

[0006] Specifically, the 1st and 2nd feet of the rectifier bridge D1 are connected in parallel with the first polyester capacitor C1, the common end between the 1st and the seventeenth resistor R17 of the rectifier bridge D is connected to the first resistor R1, the first resistor R1 is connected to the third resistor R3, the third resistor R3 is connected to the 5th foot of the detection chip U1, the 5th foot of the detection chip U1 is also connected to the second polyester capacitor C2, the second polyester capacitor C2 is also connected to the eighth resistor R8, the 6th foot of the detection chip U1 is also connected to the seventh resistor R7, the seventh resistor R7 is connected in parallel with the fourth diode D4, the seventh resistor R7 is connected to the other end of the eighth resistor R8, the seventh resistor R7 is connected to the first transistor Q1, and the first three The collector of the transistor Q1 is connected to the common end between pin 2 of the first transformer T1 and the fifth diode D5, an eleventh polyester capacitor C11 is connected in parallel between the collector and the emitter of the first transistor Q1, one end of the eleventh polyester capacitor C11 is connected to pin 2 of the first transformer T1, the other end of the eleventh polyester capacitor C11 is connected to a twelfth resistor R12, the twelfth resistor R12 is also connected in parallel with the eleventh resistor R11 and the tenth resistor R10, a fourth polyester capacitor C4 is connected to the common end between the twelfth resistor R12, the eleventh resistor R11 and the tenth resistor R10, and the other end of the fourth polyester capacitor C4 is connected to pin 4 of the detection chip U1.

[0007] Specifically, the high-frequency low-resistance circuit includes a fourteenth resistor R14, a fifteenth resistor R15, a sixth polyester capacitor C6, a sixth diode D6, a seventh polyester capacitor C7, a twelfth polyester capacitor C12, a second inductor L2, an eighth polyester capacitor C8, a ninth polyester capacitor C9 and a tenth polyester capacitor C10, the fourteenth resistor R14 and the fifteenth resistor R15 are connected in parallel, the fifteenth resistor R15 is connected to the sixth polyester capacitor C6, the sixth diode D6 is equipped with a heat sink, one end of the sixth diode D6 is connected to one end of the sixth polyester capacitor C6, and the common end between one end of the sixth diode D6 and one end of the sixth polyester capacitor C6 is connected to the second inductor L2, the seventh polyester capacitor C7 and the twelfth polyester capacitor C12 are connected in parallel, the common end between the seventh polyester capacitor C7 and the twelfth polyester capacitor C12 is connected to the sixth diode D6, and the eighth polyester capacitor C8, the ninth polyester capacitor C9 and the tenth polyester capacitor C10 are connected in parallel.

[0008] Specifically, one end of the sixth polyester capacitor C6 is also connected to the sixteenth resistor R16, the sixteenth resistor R16 is connected to pin 1 of the photocoupler U2, pin 2 of the photocoupler U2 is respectively connected to the twentieth resistor R20, the fourteenth polyester capacitor C14 and the phototube U3, the fourteenth polyester capacitor C14 is connected to the nineteenth resistor R19, and the nineteenth resistor R19 is connected to the second resistor R2 and the eighteenth resistor R18.

[0009] Specifically, a first safety capacitor CY1 and a second safety capacitor CY2 are connected between pin 5 and pin 6 of the transformer T1 , and the first safety capacitor CY1 and the second safety capacitor CY2 are connected in series.

[0010] Specifically, the 4th pin of the transformer T1 is also connected to a fifth resistor R5, the fifth resistor R5 is connected to a fourth resistor R4, the fourth resistor R4 is connected to the 5th pin of the transformer T1, and the common end between the fifth resistor R5 and the fourth resistor R4 is connected to the 3rd pin of the detection chip U1.

[0011] The beneficial effects of the utility model are as follows: the circuit is provided with a fifth polyester capacitor C5, a seventeenth resistor R17 and a thirteenth resistor R13 between the pin 1 of the first transformer T1 and the output of the rectifier bridge D1, so as to reduce the energy of a single pulse input to the first transformer T1, reduce the primary current change speed, implement voltage division, and further reduce noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings.

[0013] Figure 1 It is a control circuit diagram of the utility model. DETAILED DESCRIPTION

[0014] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0015] Reference below Figure 1 A switching power supply circuit according to an embodiment of the utility model is described, including a rectifier bridge D1 and a first transformer T1, the rectifier bridge D1 is connected to the input end of the transformer T1, the output end of the first transformer T1 is connected to a high-frequency low-resistance circuit, the output end of the high-frequency low-resistance circuit is connected to the VOUT end, a fifth polyester capacitor C5, a seventeenth resistor R17 and a thirteenth resistor R13 are arranged between pin 1 of the first transformer T1 and the output of the rectifier bridge D1, the fifth polyester capacitor C5, the seventeenth resistor R17 and the thirteenth resistor R13 are connected in parallel, a fifth diode D5 is connected to the common end between the fifth polyester capacitor C5, the seventeenth resistor R17 and the thirteenth resistor R13, the fifth diode D5 is also connected to pin 2 of the first transformer T1, the input end of the first transformer T1 is connected to a detection chip U1, the detection chip U1 is connected to a photocoupler U2, and the photocoupler U2 is also connected to the high-frequency low-resistance circuit.

[0016] This circuit is provided with a fifth polyester capacitor C5, a seventeenth resistor R17 and a thirteenth resistor R13 between the pin 1 of the first transformer T1 and the output of the rectifier bridge D1, so as to reduce the energy of a single pulse input to the first transformer T1, reduce the primary current change speed, implement voltage division, and further reduce noise.

[0017] Among them, the AC enters the rectifier bridge D1 to convert into DC, and the DC is input to the combination of the fifth polyester capacitor C5, the seventeenth resistor R17 and the thirteenth resistor R13 to implement voltage division and reduce the primary current change speed, and then input to the input end of the transformer T1. The output end of the transformer T1 outputs DC, and the DC passes through the high-frequency low-resistance circuit. The high-frequency low-resistance circuit outputs 12V DC. The high-frequency low-resistance circuit mainly plays the role of filtering, oscillation, delay, trapping, etc., and also has the functions of screening signals, filtering noise, stabilizing current and suppressing electromagnetic wave interference. The optocoupler U2 is used to detect the DC output of the transformer T1 and feedback it to the detection chip U1, so as to implement the current value of the adjustment target.

[0018] In the present circuit, the 1st and 2nd pins of the rectifier bridge D1 are connected in parallel with a first polyester capacitor C1, which functions to stabilize direct current. The common end between the 1st pin of the rectifier bridge D and the seventeenth resistor R17 is connected with a first resistor R1, which is connected with a third resistor R3, which is connected with pin 5 of the detection chip U1. The rectifier bridge D1 provides power for the detection chip U1, and the combination of the first resistor R1 and the third resistor R3 functions to limit the voltage and protect the detection chip U1. The 5th pin of the detection chip U1 is also connected with a second polyester capacitor C2, which is also connected with an eighth resistor R8. The 6th pin of the detection chip U1 is also connected with a seventh resistor R7, which is connected with a fourth diode D4 in parallel, which is connected with the other end of the eighth resistor R8, and which is connected with the seventh resistor R7. There is a first transistor Q1, the detection chip U1 controls the on-off state of the first transistor Q1, the seventh resistor R7 is used to protect the base of the first transistor Q1, and the collector of the first transistor Q1 is connected to the common end between the 2 of the first transformer T1 and the fifth diode D5, the collector and the emitter of the first transistor Q1 are connected in parallel with the eleventh polyester capacitor C11, one end of the eleventh polyester capacitor C11 is connected to the 2nd foot of the first transformer T1, the other end of the eleventh polyester capacitor C11 is connected to the twelfth resistor R12, the twelfth resistor R12 is also connected in parallel with the eleventh resistor R11 and the tenth resistor R10, the common end between the twelfth resistor R12, the eleventh resistor R11 and the tenth resistor R10 is connected to the fourth polyester capacitor C4, the other end of the fourth polyester capacitor C4 is connected to the 4th foot of the detection chip U1. The detection chip U1 controls the on-off of the 4th and 5th feet of the first transformer T1 to adjust the DC level of the first transformer T1.

[0019] The high-frequency low-resistance circuit of this circuit includes a fourteenth resistor R14, a fifteenth resistor R15, a sixth polyester capacitor C6, a sixth diode D6, a seventh polyester capacitor C7, a twelfth polyester capacitor C12, a second inductor L2, an eighth polyester capacitor C8, a ninth polyester capacitor C9 and a tenth polyester capacitor C10. The fourteenth resistor R14 and the fifteenth resistor R15 are connected in parallel, the fifteenth resistor R15 is connected to the sixth polyester capacitor C6, the sixth diode D6 is equipped with a heat sink, one end of the sixth diode D6 is connected to one end of the sixth polyester capacitor C6, and a common end between one end of the sixth diode D6 and one end of the sixth polyester capacitor C6 is connected to the second inductor L2, the seventh polyester capacitor C7 and the twelfth polyester capacitor C12 are connected in parallel, the common end between the seventh polyester capacitor C7 and the twelfth polyester capacitor C12 is connected to the sixth diode D6, and the eighth polyester capacitor C8, the ninth polyester capacitor C9 and the tenth polyester capacitor C10 are connected in parallel. The high-frequency low-resistance circuit implements the high-frequency effect through the combination of the second inductor L2 and the second inductor L1, and the heat sink is used to cool the sixth diode D6. The sixth polyester capacitor C6, the sixth diode D6, the seventh polyester capacitor C7 and the twelfth polyester capacitor C12 combine to stabilize the voltage.

[0020] One end of the sixth polyester capacitor C6 in the circuit is also connected to the sixteenth resistor R16, the sixteenth resistor R16 is connected to the pin 1 of the photocoupler U2, the pin 2 of the photocoupler U2 is respectively connected to the twentieth resistor R20, the fourteenth polyester capacitor C14 and the phototube U3, the fourteenth polyester capacitor C14 is connected to the nineteenth resistor R19, the nineteenth resistor R19 is connected to the second resistor R2 and the eighteenth resistor R18. The information of the photocoupler U2 is fed back to the detection chip U1, and the thirteenth polyester capacitor C13 plays a role in slowing down the flow, reducing the impact of the current on the detection chip U1, and improving the stability of the detection.

[0021] In this circuit, the first safety capacitor CY1 and the second safety capacitor CY2 are connected between the 5th and 6th pins of the transformer T1, and the first safety capacitor CY1 and the second safety capacitor CY2 are connected in series. The first safety capacitor CY1 and the second safety capacitor CY2 are combined to prevent electric shock and personal safety after the capacitor fails. Safety capacitors are usually only used for filtering in anti-interference circuits.

[0022] In this circuit, the 4th pin of the transformer T1 is also connected to a fifth resistor R5, the fifth resistor R5 is connected to a fourth resistor R4, the fourth resistor R4 is connected to the 5th pin of the transformer T1, and the common end between the fifth resistor R5 and the fourth resistor R4 is connected to the 3rd pin of the detection chip U1. The combination of the fifth resistor R5 and the fourth resistor R4 plays the role of protecting the 2nd pin of the detection chip U1 and detecting the use status of the transformer T1.

[0023] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A switching power supply circuit, comprising a rectifier bridge D1 and a first transformer T1, wherein the rectifier bridge D1 is connected to an input end of the transformer T1, characterized in that: The output end of the first transformer T1 is connected to a high-frequency low-resistance circuit, and the output end of the high-frequency low-resistance circuit is connected to the VOUT end. A fifth polyester capacitor C5, a seventeenth resistor R17 and a thirteenth resistor R13 are provided between pin 1 of the first transformer T1 and the output of the rectifier bridge D1. The fifth polyester capacitor C5, the seventeenth resistor R17 and the thirteenth resistor R13 are connected in parallel. A fifth diode D5 is connected to a common end between the fifth polyester capacitor C5, the seventeenth resistor R17 and the thirteenth resistor R13. The fifth diode D5 is also connected to pin 2 of the first transformer T1. The input end of the first transformer T1 is connected to a detection chip U1, the detection chip U1 is connected to a photocoupler U2, and the photocoupler U2 is also connected to the high-frequency low-resistance circuit.

2. A switching power supply circuit according to claim 1, characterized in that: The 1st and 2nd pins of the rectifier bridge D1 are connected in parallel with the first polyester capacitor C1, the common end between the 1st pin of the rectifier bridge D and the seventeenth resistor R17 is connected with the first resistor R1, the first resistor R1 is connected with the third resistor R3, the third resistor R3 is connected with the 5th pin of the detection chip U1, the 5th pin of the detection chip U1 is also connected with the second polyester capacitor C2, the second polyester capacitor C2 is also connected with the eighth resistor R8, the 6th pin of the detection chip U1 is also connected with the seventh resistor R7, the seventh resistor R7 is connected with the fourth diode D4 in parallel, the seventh resistor R7 is connected with the other end of the eighth resistor R8, the seventh resistor R7 is connected with the first transistor Q1, the first transistor Q The collector of the first transistor Q1 is connected to the common end between pin 2 of the first transformer T1 and the fifth diode D5, an eleventh polyester capacitor C11 is connected in parallel between the collector and the emitter of the first transistor Q1, one end of the eleventh polyester capacitor C11 is connected to pin 2 of the first transformer T1, the other end of the eleventh polyester capacitor C11 is connected to a twelfth resistor R12, the twelfth resistor R12 is also connected in parallel with the eleventh resistor R11 and the tenth resistor R10, a fourth polyester capacitor C4 is connected to the common end between the twelfth resistor R12, the eleventh resistor R11 and the tenth resistor R10, and the other end of the fourth polyester capacitor C4 is connected to pin 4 of the detection chip U1.

3. A switching power supply circuit according to claim 1, characterized in that: The high-frequency low-resistance circuit includes a fourteenth resistor R14, a fifteenth resistor R15, a sixth polyester capacitor C6, a sixth diode D6, a seventh polyester capacitor C7, a twelfth polyester capacitor C12, a second inductor L2, an eighth polyester capacitor C8, a ninth polyester capacitor C9 and a tenth polyester capacitor C10. The fourteenth resistor R14 and the fifteenth resistor R15 are connected in parallel, the fifteenth resistor R15 is connected to the sixth polyester capacitor C6, the sixth diode D6 is provided with a heat sink, one end of the sixth diode D6 is connected to one end of the sixth polyester capacitor C6, a common end between one end of the sixth diode D6 and one end of the sixth polyester capacitor C6 is connected to the second inductor L2, the seventh polyester capacitor C7 and the twelfth polyester capacitor C12 are connected in parallel, the common end between the seventh polyester capacitor C7 and the twelfth polyester capacitor C12 is connected to the sixth diode D6, and the eighth polyester capacitor C8, the ninth polyester capacitor C9 and the tenth polyester capacitor C10 are connected in parallel.

4. A switching power supply circuit according to claim 3, characterized in that: One end of the sixth polyester capacitor C6 is also connected to the sixteenth resistor R16, the sixteenth resistor R16 is connected to the pin 1 of the photocoupler U2, the pin 2 of the photocoupler U2 is respectively connected to the twentieth resistor R20, the fourteenth polyester capacitor C14 and the phototube U3, the fourteenth polyester capacitor C14 is connected to the nineteenth resistor R19, and the nineteenth resistor R19 is connected to the second resistor R2 and the eighteenth resistor R18.

5. The switching power supply circuit according to claim 1, characterized in that: A first safety capacitor CY1 and a second safety capacitor CY2 are connected between pins 5 and 6 of the transformer T1 , and the first safety capacitor CY1 and the second safety capacitor CY2 are connected in series.

6. A switching power supply circuit according to claim 5, characterized in that: Pin 4 of the transformer T1 is also connected to a fifth resistor R5, which is connected to a fourth resistor R4. The fourth resistor R4 is connected to pin 5 of the transformer T1, and a common end between the fifth resistor R5 and the fourth resistor R4 is connected to pin 3 of the detection chip U1.

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