CN209994272U - Ripple noise suppression device of switching power supply - Google Patents
Ripple noise suppression device of switching power supply Download PDFInfo
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Abstract
The utility model discloses a ripple noise suppression device of a switching power supply, which comprises a control module, a switch module, a voltage output module and a feedback suppression module, wherein the switch module is electrically connected with the control module, the switch module is electrically connected with the voltage output module, the feedback suppression module is electrically connected with the voltage output module, and the feedback suppression module is electrically connected with the control module; the feedback suppression module comprises a sampling unit, a voltage stabilizing unit and an optical coupling unit, the sampling unit is electrically connected with the voltage output module, the sampling unit is electrically connected with the voltage stabilizing unit, the voltage stabilizing unit is electrically connected with the input end of the optical coupling unit, and the optical coupling unit is electrically connected with the control module. The utility model discloses can reduce ripple noise effectively, stabilize the voltage of output to under the condition of product space restriction, need not add a plurality of electrolytic capacitor, multistage filter inductance and solid-state electric capacity, realize that ripple noise reduces to required index scope, thereby can reduce cost, make the structure of device compacter, the structure is simpler.
Description
Technical Field
The utility model relates to a noise elimination structure field especially relates to a switching power supply's ripple noise suppression device.
Background
In recent years, the development of the switching power supply is very rapid, because the switching power supply has the characteristics of high efficiency, small volume and high reliability, the switching power supply has replaced the traditional linear stabilized power supply as the power supply of the system in many fields, at present, the switching power supply has been widely applied to various control devices, communication devices and household appliances, the electromagnetic interference problem and the electromagnetic compatibility problem with other electronic devices have become the focus of people's attention, the electromagnetic interference and the related problems thereof will be researched more in the future, and now under the trend that the switching power supply has smaller volume and larger power density: EMI, EMC issues become a critical factor for the stability of the switching power supply and are also one of the most easily overlooked aspects. The EMI suppression technology of the switching power supply has an important position in the design of the switching power supply, practices prove that the EMI problem is considered and solved earlier, the cost is smaller, the effect is better, the working modes of the existing switching power supply mainly comprise PWM (pulse width modulation), Pulse Frequency Modulation (PFM) modes and the like, the switching power supply can be divided into a full bridge type, a half bridge type, a push-pull type and the like according to the main circuit type, and strong ripple noise (ripple noise) can be generated no matter what type of switching power supply is in working. They are conducted outwards in common mode or differential mode through the supply lines, while also radiating into the surrounding space. The switching power supply is also sensitive to external noise intruding from the power grid and generates interference through the external noise to other electronic equipment, and the larger the noise of the power supply is, the larger the output ripple is. The strong ripple waves can cause the generation of surge voltage or current, the efficiency of a power supply is reduced, and the electric appliances in use are burnt; the logic relation of the digital circuit is interfered, and the normal work of the digital circuit is influenced; the image equipment and the sound equipment can not work normally, etc.
The definition of ripple (ripple) refers to an alternating current component superimposed on a constant amount of direct current in a direct current voltage or current, and we finally aim to reduce the output ripple to a tolerable level.
Currently, there are several common methods for suppressing power supply ripple noise: 1. increasing output low-frequency filter inductance; 2. Increasing electrolytic capacitors and increasing output electrolytic capacitor parameters; 3. increasing an output ceramic chip type capacitor; 4. the output capacitor is high-frequency low-resistance or even solid capacitor.
The prior art has the defects that: 1. the cost is increased and the product space is increased by increasing the output low-frequency filter inductance, and the problem is difficult to improve if the designed product size is not allowed; 2. the cost is increased and the product space is increased due to the increase of the electrolytic capacitor and the increase of the output electrolytic capacitor parameters, and the problems are difficult to improve if the designed product size permits; the electrolytic capacitor can not be increased without limit, and output low-frequency ripple wave residue can be caused; 3. the cost is increased by adding a plurality of output ceramic chip capacitors; 4. the output capacitor is a high-frequency low-resistance capacitor, even a solid capacitor, so that the cost is increased and exceeds the budget price, and the output capacitor is not easy to accept by customers.
SUMMERY OF THE UTILITY MODEL
The utility model aims at overcoming the weak point among the prior art, providing a switching power supply's ripple noise suppression device, under the condition of product space restriction, need not add a plurality of electrolytic capacitor, multistage filter inductance and solid-state electric capacity, realize that the ripple noise reduces to required index range to can reduce cost, make the structure of device compacter, the structure is simpler.
The purpose of the utility model is realized through the following technical scheme:
a ripple noise suppression apparatus of a switching power supply, comprising: the voltage feedback control circuit comprises a control module, a switch module, a voltage output module and a feedback suppression module, wherein the input end of the switch module is electrically connected with the control module, the output end of the switch module is electrically connected with the voltage output module, the acquisition end of the feedback suppression module is electrically connected with the voltage output module, and the output end of the feedback suppression module is electrically connected with the feedback end of the control module;
the feedback suppression module comprises a sampling unit, a voltage stabilizing unit and an optical coupling unit, one end of the sampling unit is electrically connected with the output end of the voltage output module, the other end of the sampling unit is electrically connected with the voltage stabilizing unit, the output end of the voltage stabilizing unit is electrically connected with the input end of the optical coupling unit, and the output end of the optical coupling unit is electrically connected with the feedback end of the control module.
In one embodiment, the sampling unit includes a resistor R8 and a resistor R9, a first end of the resistor R8 is electrically connected to the output end of the voltage output module, and a second end of the resistor R8 is grounded through the resistor R9.
In one embodiment, the voltage regulation unit includes a capacitor C3, a resistor R7, and a voltage regulator U6, one end of the capacitor C3 is electrically connected to the second end of the resistor R8, the other end of the capacitor C3 is electrically connected to the first end of the resistor R7, the second end of the resistor R7 is electrically connected to the cathode of the voltage regulator U6, the anode of the voltage regulator U6 is grounded, and the reference electrode of the voltage regulator U6 is also electrically connected to the second end of the resistor R8.
In one embodiment, the optical coupling unit includes a resistor R5, a resistor R6, and a photo coupler PC1, a first end of the resistor R6 is electrically connected to the output end of the voltage output module, second ends of the resistors R6 are electrically connected to a first end of the resistor R5 and an anode of the photo coupler PC1, respectively, a second end of the resistor R5 is electrically connected to a cathode of the photo coupler PC1 and the output end of the voltage stabilizing unit, respectively, and an output end of the photo coupler PC1 is electrically connected to the control module.
In one embodiment, the control module includes a PWM control chip and a capacitor C1, one end of the capacitor C1 is electrically connected to a feedback pin of the PWM control chip, the other end of the capacitor C1 is grounded, and the feedback pin of the PWM control chip is further electrically connected to an output terminal of the optical coupling unit.
In one embodiment, the switch module includes a driving unit and a switch unit, an input end of the driving unit is electrically connected to an output end of the control module, an output end of the driving unit is electrically connected to the switch unit, and an output end of the switch unit is electrically connected to an input end of the voltage output module.
In one embodiment, the driving unit includes a resistor R1 and a diode D1, a first terminal of the resistor R1 is electrically connected to the output terminal of the control module, a second terminal of the resistor R1 is electrically connected to the input terminal of the switching unit, a cathode of the diode D1 is electrically connected to a first terminal of the resistor R1, and an anode of the diode D1 is electrically connected to a second terminal of the resistor R1.
In one embodiment, the switching unit includes a resistor R2, a capacitor C4, and a MOS transistor Q3, a G-pole of the MOS transistor Q3 is electrically connected to the output terminal of the driving unit, a D-pole of the MOS transistor Q3 is electrically connected to the input terminal of the voltage output module, an S-pole of the MOS transistor Q3 is electrically connected to the control module, one end of the resistor R2 is electrically connected to the G-pole of the MOS transistor Q3, the other end of the resistor R2 is grounded, and two ends of the capacitor C4 are respectively connected to the D-pole and the S-pole of the MOS transistor Q3.
In one embodiment, the voltage output module includes a transformer T1, a diode D2, and a capacitor C6, wherein a primary of the transformer T1 is electrically connected to the output terminal of the switch module, a secondary of the transformer T1 is electrically connected to an anode of the diode D2, a cathode of the diode D2 is electrically connected to one end of the capacitor C6, and the other end of the capacitor C6 is grounded.
In one embodiment, the ripple noise suppression device of the switching power supply further includes a shielding copper foil and an insulating gasket, the shielding copper foil is used for being embedded between the body of the MOS transistor Q3 and the radiator of the MOS transistor Q3, and one side surface of the shielding copper foil is attached to the body of the MOS transistor Q3, and the insulating gasket is disposed on one side surface of the shielding copper foil, which is far away from the MOS transistor Q3.
The utility model discloses compare in prior art's advantage and beneficial effect as follows:
the utility model relates to a switching power supply's ripple noise suppression device, through setting up sampling unit, steady voltage unit and opto-coupler unit, can reduce the ripple noise effectively, stabilize the voltage of output to under the condition of product space restriction, need not add a plurality of electrolytic capacitor, multistage filter inductance and solid-state electric capacity, realize that the ripple noise reduces to required index range, thereby can reduce cost, make the structure of device compacter, the structure is simpler.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a functional block diagram of a ripple noise suppression apparatus of a switching power supply according to an embodiment of the present invention;
fig. 2 is a circuit diagram of a ripple noise suppression apparatus of the switching power supply shown in fig. 1;
fig. 3 is a schematic structural diagram of a ripple noise suppression device of the switching power supply shown in fig. 1.
Detailed Description
In order to facilitate understanding of the present invention, the present invention will be described more fully hereinafter with reference to the accompanying drawings. The preferred embodiments of the present invention are shown in the drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not represent the only embodiments.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
To remove ripple noise, and to achieve the desired product, it is clear first where the ripple is the main source of the output ripple of the switching power supply? The output ripple of the switching power supply mainly comes from the following aspects: 1. inputting low-frequency ripples; 2. high-frequency ripples; 3. common mode ripple noise caused by parasitic parameters; 4. ultrahigh frequency resonance noise generated in the switching process of the power device; 5. the closed loop regulation controls the resulting ripple noise.
The method for eliminating ripple noise comprises the following steps: the ripple is related to the filter capacitance capacity of the output circuit, the alternating current ripple is transformed and attenuated by the DC/DC high-frequency transformer, and then appears as low-frequency noise at the output end of the switching power supply, the size of the low-frequency noise is determined by the transformation ratio of the DC/DC high-frequency transformer and the gain of a control chip (PWM IC), and filtering measures must be taken for the low-frequency power supply ripple to realize the low-ripple output of the switching power supply. Except for increasing the inductance and capacitance parameters of the output low-frequency filter, the low-frequency ripple noise is reduced to the required index.
The method mainly uses a feedforward control method to reduce low-frequency ripple components, and is mainly used for large ripple noise caused by some pure hysteresis or capacity hysteresis.
Referring to fig. 1, a ripple noise suppression apparatus of a switching power supply includes: the feedback suppression circuit comprises a control module 100, a switch module 200, a voltage output module 300 and a feedback suppression module 400, wherein the input end of the switch module is electrically connected with the control module, the output end of the switch module is electrically connected with the voltage output module, the acquisition end of the feedback suppression module is electrically connected with the voltage output module, and the output end of the feedback suppression module is electrically connected with the feedback end of the control module. It should be noted that the control module 100 is configured to control the output of the voltage; the switch module 200 is used for switching off or switching on the output of the voltage; the voltage output module 300 is configured to output a stable voltage; the feedback suppression module 400 is used for collecting the voltage at the output end and transmitting the voltage to the control module in time, so as to adjust the voltage at the output end, reduce the ripple noise in the output voltage and improve the stability of voltage output.
Referring to fig. 1, the feedback suppression module 400 includes a sampling unit 410, a voltage regulation unit 420, and an optical coupling unit 430, where one end of the sampling unit is electrically connected to the output end of the voltage output module, the other end of the sampling unit is electrically connected to the voltage regulation unit, the output end of the voltage regulation unit is electrically connected to the input end of the optical coupling unit, and the output end of the optical coupling unit is electrically connected to the feedback end of the control module. It should be noted that the sampling unit 410 is used for acquiring a voltage at an output end; the voltage stabilizing unit 420 is used for stabilizing the acquired voltage; the optical coupling unit 430 is configured to output the received regulated voltage to a feedback end of the control module.
Referring to fig. 2, the sampling unit includes a resistor R8 and a resistor R9, a first end of the resistor R8 is electrically connected to the output end of the voltage output module, and a second end of the resistor R8 is grounded through the resistor R9.
Further, the voltage stabilizing unit includes a capacitor C3, a resistor R7, and a voltage regulator U6, wherein one end of the capacitor C3 is electrically connected to the second end of the resistor R8, the other end of the capacitor C3 is electrically connected to the first end of the resistor R7, the second end of the resistor R7 is electrically connected to the cathode of the voltage regulator U6, the anode of the voltage regulator U6 is grounded, and the reference electrode of the voltage regulator U6 is also electrically connected to the second end of the resistor R8.
Specifically, the optical coupling unit includes a resistor R5, a resistor R6, and a photocoupler PC1, a first end of the resistor R6 is electrically connected to the output terminal of the voltage output module, a second end of the resistor R6 is electrically connected to the first end of the resistor R5 and the anode of the photocoupler PC1, a second end of the resistor R5 is electrically connected to the cathode of the photocoupler PC1 and the output terminal of the voltage stabilizing unit, and an output terminal of the photocoupler PC1 is electrically connected to the control module.
In the figure, the output end voltage is VB +, the sampling voltage is divided and limited from the output voltage (VB +) through a resistor R8 with a fixed resistance value and a resistor R9, and is also added to a precision voltage stabilizer U6(TL431 controllable shunt reference) together with a light emitting diode inside a photoelectric coupler (PC1), the light intensity of a base electrode of a photosensitive triode in the photoelectric coupler is increased, and the CE junction conducting voltage of the photoelectric coupler is reduced. The feedback voltage is fed back to an error amplifying and comparing circuit of a feedback pin of a preceding stage PWM IC, the duty ratio of an output pin of the PWM IC is controlled, namely the duty ratio of a GATE pin of the PWM IC is controlled, the conduction time of a switching tube in an output switching module is driven, and the output voltage (VB +) achieves stability.
The capacitor C3 and the resistor R7 in fig. 2 form an RC frequency compensation network, the voltage regulator U6(TL431 controllable shunt reference) feeds back and amplifies the error to drive the light emitting part of a photocoupler, and the feedback voltage PWM IC pin 2 obtained from the photocoupler light sensing part on the main side adjusts the duty ratio of the PWM pin 6. The capacitor C3 should not be too large when moved, and is between 0.1uF and 0.22uF, the too large will affect the corresponding speed to slow down, leading to the output voltage VB + ripple noise increase, and through adjusting the capacitance value of the capacitor C3, the frequency compensation is changed, and the ripple noise can be reduced to the required index.
Referring to fig. 2, the control module includes a PWM control chip and a capacitor C1, one end of the capacitor C1 is electrically connected to a feedback pin of the PWM control chip, the other end of the capacitor C1 is grounded, and the feedback pin of the PWM control chip is further electrically connected to an output terminal of the optocoupler unit.
It should be noted that, the capacitor C1 in fig. 2 is connected to the 2 nd pin of the PWM IC, that is, the voltage feedback pin, and the control loop is closed by connecting the photocoupler, so as to achieve the purpose of adjusting the output voltage to achieve stability, the capacitor C1 is a compensation capacitor, and the selection for one movement is not too large, and between 100PF and 0.01uF, too large will also affect the corresponding speed to slow down, resulting in unstable output voltage VB +, increasing ripple noise, and the output voltage ripple noise can be reduced to the required index by adjusting the capacitance value of the capacitor C1.
Referring to fig. 1, the switch module 200 includes a driving unit 210 and a switch unit 220, an input end of the driving unit is electrically connected to an output end of the control module, an output end of the driving unit is electrically connected to the switch unit, and an output end of the switch unit is electrically connected to an input end of the voltage output module. It should be noted that the driving unit 210 is configured to drive the switching unit to be turned on and output a voltage; the switch unit is used for realizing the conduction function of voltage output.
Referring to fig. 2, the driving unit includes a resistor R1 and a diode D1, a first end of the resistor R1 is electrically connected to the output end of the control module, a second end of the resistor R1 is electrically connected to the input end of the switching unit, a cathode of the diode D1 is electrically connected to a first end of the resistor R1, and an anode of the diode D1 is electrically connected to a second end of the resistor R1.
Referring to fig. 2, the switch unit includes a resistor R2, a capacitor C4, and a MOS transistor Q3, a G-pole of the MOS transistor Q3 is electrically connected to the output terminal of the driving unit, a D-pole of the MOS transistor Q3 is electrically connected to the input terminal of the voltage output module, an S-pole of the MOS transistor Q3 is electrically connected to the control module, one end of the resistor R2 is electrically connected to the G-pole of the MOS transistor Q3, the other end of the resistor R2 is grounded, and two ends of the capacitor C4 are respectively connected to the D-pole and the S-pole of the MOS transistor Q3.
The resistor R1 in fig. 2 belongs to a driving resistor, one end of which is connected to the 6 th pin of the PWM IC, and the other end of which is connected to the gate driving pin of the external MOS transistor Q3. The driving resistor of the resistor R1 is properly changed, the resistor R1 cannot be changed to be too large, the ripple noise of the output voltage VB + can be improved by adjusting the driving resistor between 20 ohms and 47 ohms generally according to actual circuit adjustment, the switching speed of the MOS transistor Q3 is changed by changing the size of the driving resistor, the switching speed of the MOS transistor Q3 is reduced by increasing the resistance value of the resistor R1, common mode noise can be inhibited by changing the size of the resistor R1 by the method, and the requirement that the output voltage drop ripple noise is reduced to a required index can be met.
Meanwhile, the feedback voltage is fed back to an error amplifying and comparing circuit of a feedback pin of a preceding stage PWM IC, the duty ratio of an output pin of the PWM IC is controlled, namely the duty ratio of a GATE pin of the PWM IC is controlled, the on-time of an external MOSFET (Q3) is driven and output, and the output voltage (VB +) achieves stability.
It should be noted that the voltage output module includes a transformer T1, a diode D2, and a capacitor C6, the primary of the transformer T1 is electrically connected to the output terminal of the switch module, the secondary of the transformer T1 is electrically connected to the anode of the diode D2, the cathode of the diode D2 is electrically connected to one end of the capacitor C6, and the other end of the capacitor C6 is grounded.
Referring to fig. 3, the ripple noise suppression device of the switching power supply further includes a shielding copper foil and an insulating spacer, the shielding copper foil is embedded between the body of the MOS transistor Q3 and the heat sink of the MOS transistor Q3, a side surface of the shielding copper foil is attached to the body of the MOS transistor Q3, and the insulating spacer is disposed on a side surface of the shielding copper foil away from the MOS transistor Q3.
It should be noted that, when the power MOS transistor Q3 in fig. 3 is assembled with the heat sink 10, the mounting is performed according to the method in fig. 3, that is, the shielding copper foil 20 is disposed on the transistor, so that noise propagation caused by parasitic capacitance can be reduced, the coupling capacitance between the moving point and the ground is reduced, and the most basic moving point is generally the D pole of the switching power transistor Q3, and the D pole passing through the switching power transistor Q3 has the effect of heat dissipation and is attached to the large-area heat sink 10, while the coupling capacitance of the large-area heat sink 10 to the ground is large, so that the D pole of the switching power transistor Q3 should not be directly connected to the large-area heat sink, but be separated from the shielding copper foil 20 by the insulating spacer 30, thereby achieving the reduction of ripple noise to the required index, thus effectively reducing the noise, stabilizing the output voltage, and in case of the product space limitation, need not add a plurality of electrolytic capacitors, multistage filter inductance and solid-state electric capacity, realize that ripple noise reduces to required index range to can reduce cost, make the structure of device compacter, the structure is simpler.
The utility model discloses compare in prior art's advantage and beneficial effect as follows:
the utility model relates to a switching power supply's ripple noise suppression device, through setting up sampling unit, steady voltage unit and opto-coupler unit, can reduce the ripple noise effectively, stabilize the voltage of output to under the condition of product space restriction, need not add a plurality of electrolytic capacitor, multistage filter inductance and solid-state electric capacity, realize that the ripple noise reduces to required index range, thereby can reduce cost, make the structure of device compacter, the structure is simpler.
The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (10)
1. A ripple noise suppression apparatus of a switching power supply, comprising: the voltage feedback control circuit comprises a control module, a switch module, a voltage output module and a feedback suppression module, wherein the input end of the switch module is electrically connected with the control module, the output end of the switch module is electrically connected with the voltage output module, the acquisition end of the feedback suppression module is electrically connected with the voltage output module, and the output end of the feedback suppression module is electrically connected with the feedback end of the control module;
the feedback suppression module comprises a sampling unit, a voltage stabilizing unit and an optical coupling unit, one end of the sampling unit is electrically connected with the output end of the voltage output module, the other end of the sampling unit is electrically connected with the voltage stabilizing unit, the output end of the voltage stabilizing unit is electrically connected with the input end of the optical coupling unit, and the output end of the optical coupling unit is electrically connected with the feedback end of the control module.
2. The ripple noise suppression device of claim 1, wherein the sampling unit comprises a resistor R8 and a resistor R9, a first end of the resistor R8 is electrically connected to the output terminal of the voltage output module, and a second end of the resistor R8 is grounded via the resistor R9.
3. The ripple noise suppression device of the switching power supply according to claim 2, wherein the voltage regulator unit includes a capacitor C3, a resistor R7, and a regulator U6, one end of the capacitor C3 is electrically connected to the second end of the resistor R8, the other end of the capacitor C3 is electrically connected to the first end of the resistor R7, the second end of the resistor R7 is electrically connected to the cathode of the regulator U6, the anode of the regulator U6 is grounded, and the reference pole of the regulator U6 is further electrically connected to the second end of the resistor R8.
4. The ripple noise suppression device of the switching power supply according to claim 1, wherein the optical coupling unit comprises a resistor R5, a resistor R6 and a photo coupler PC1, a first end of the resistor R6 is electrically connected to the output end of the voltage output module, a second end of the resistor R6 is electrically connected to a first end of the resistor R5 and an anode of the photo coupler PC1, respectively, a second end of the resistor R5 is electrically connected to a cathode of the photo coupler PC1 and an output end of the voltage stabilizing unit, respectively, and an output end of the photo coupler PC1 is electrically connected to the control module.
5. The ripple noise suppression device of switching power supply according to claim 1, wherein the control module comprises a PWM control chip and a capacitor C1, one end of the capacitor C1 is electrically connected to a feedback pin of the PWM control chip, the other end of the capacitor C1 is grounded, and the feedback pin of the PWM control chip is further electrically connected to the output terminal of the optical coupling unit.
6. The ripple noise suppression device of the switching power supply according to claim 1, wherein the switching module includes a driving unit and a switching unit, an input terminal of the driving unit is electrically connected to an output terminal of the control module, an output terminal of the driving unit is electrically connected to the switching unit, and an output terminal of the switching unit is electrically connected to an input terminal of the voltage output module.
7. The ripple noise suppression device of the switching power supply according to claim 6, wherein the driving unit comprises a resistor R1 and a diode D1, a first end of the resistor R1 is electrically connected to the output terminal of the control module, a second end of the resistor R1 is electrically connected to the input terminal of the switching unit, a cathode of the diode D1 is electrically connected to a first end of the resistor R1, and an anode of the diode D1 is electrically connected to a second end of the resistor R1.
8. The ripple noise suppression device of the switching power supply according to claim 6, wherein the switching unit includes a resistor R2, a capacitor C4 and a MOS transistor Q3, a G-pole of the MOS transistor Q3 is electrically connected to the output terminal of the driving unit, a D-pole of the MOS transistor Q3 is electrically connected to the input terminal of the voltage output module, an S-pole of the MOS transistor Q3 is electrically connected to the control module, one end of the resistor R2 is electrically connected to the G-pole of the MOS transistor Q3, the other end of the resistor R2 is grounded, and two ends of the capacitor C4 are respectively connected to the D-pole and the S-pole of the MOS transistor Q3.
9. The ripple noise suppression device of the switching power supply according to claim 1, wherein the voltage output module comprises a transformer T1, a diode D2 and a capacitor C6, wherein a primary side of the transformer T1 is electrically connected to the output terminal of the switching module, a secondary side of the transformer T1 is electrically connected to an anode of the diode D2, a cathode of the diode D2 is electrically connected to one end of the capacitor C6, and the other end of the capacitor C6 is grounded.
10. The ripple noise suppression device of the switching power supply according to claim 8, further comprising a shielding copper foil and an insulating spacer, wherein the shielding copper foil is embedded between the body of the MOS transistor Q3 and the heat sink of the MOS transistor Q3, and one side of the shielding copper foil is attached to the body of the MOS transistor Q3, and the insulating spacer is disposed on a side of the shielding copper foil away from the MOS transistor Q3.
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| CN201920779938.6U CN209994272U (en) | 2019-05-27 | 2019-05-27 | Ripple noise suppression device of switching power supply |
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| CN201920779938.6U CN209994272U (en) | 2019-05-27 | 2019-05-27 | Ripple noise suppression device of switching power supply |
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