CN110233563B - Frequency modulation circuit and switching power supply - Google Patents
Frequency modulation circuit and switching power supply Download PDFInfo
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- CN110233563B CN110233563B CN201910672511.0A CN201910672511A CN110233563B CN 110233563 B CN110233563 B CN 110233563B CN 201910672511 A CN201910672511 A CN 201910672511A CN 110233563 B CN110233563 B CN 110233563B
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- 238000001514 detection method Methods 0.000 claims abstract description 22
- 239000003990 capacitor Substances 0.000 claims abstract description 18
- 230000001052 transient effect Effects 0.000 claims description 8
- 230000001629 suppression Effects 0.000 claims description 5
- 230000010355 oscillation Effects 0.000 abstract description 12
- 238000000034 method Methods 0.000 abstract description 4
- 230000002035 prolonged effect Effects 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000000087 stabilizing effect Effects 0.000 description 3
- 230000006978 adaptation Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0048—Circuits or arrangements for reducing losses
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The embodiment of the invention provides a frequency modulation circuit and a switching power supply, wherein the frequency modulation circuit is applied to the switching power supply, and the switching power supply comprises: the power chip, the resistance detection end of power chip passes through first resistance ground connection, and the frequency modulation circuit includes: the source electrode of the first MOS tube is grounded, the grid electrode is connected with the load feedback signal input end of the power supply chip through the first capacitor so as to receive a load feedback signal of the switching power supply, and the drain electrode is connected with the resistance detection end of the power supply chip through the second resistor so as to adjust the resistance value of the resistance detection end according to the load feedback signal and adjust the working frequency of the switching power supply. Through the scheme, the resistance value of the resistance detection end can be automatically adjusted according to the size of the load in the use process of the switching power supply, so that the working frequency of the switching power supply is consistent with the oscillation frequency of the output voltage of the switching power supply all the time, the use efficiency of the switching power supply is improved, the power consumption is reduced, and the service life of the switching power supply is prolonged.
Description
Technical Field
The invention relates to the technical field of power supplies, in particular to a frequency modulation circuit and a switching power supply.
Background
A switch mode power supply (Switch Mode Power Supply, SMPS for short), also called a switching power supply, a switching converter, is a high frequency power conversion device, which is a type of power supply. The function is to convert a voltage of one level into a voltage or current required by the user terminal through different types of structures. The input of the switching power supply is mostly an ac power supply (e.g. mains supply) or a dc power supply, while the output is mostly a device requiring a dc power supply, such as a personal computer, and the switching power supply performs voltage and current conversion between the two.
In the use process of the existing switching power supply, when the working frequency of the switching power supply is consistent with the oscillation frequency of the output direct-current voltage value of the switching power supply, the switching power supply works in an optimal state, the power consumption is small, the direct-current voltage feedback signal value of the switching power supply can be changed along with the size of a load, and the oscillation frequency of the direct-current voltage value can also be changed, however, once the existing switching power supply is designed, the working frequency of the existing switching power supply is fixed, so that when the size of the load is changed, the working frequency of the switching power supply is difficult to be consistent with the oscillation frequency of the output direct-current voltage value of the switching power supply, the power consumption of the switching power supply can be increased, the use efficiency of the switching power supply is affected, and the switching power supply is damaged seriously.
Disclosure of Invention
The invention aims to provide a frequency modulation circuit and a switching power supply, which are used for solving the problem that the switching power supply cannot adjust the oscillation frequency according to the size of a load.
According to a first aspect, an embodiment of the present invention provides a frequency modulation circuit, the frequency modulation circuit being applied to a switching power supply, the switching power supply comprising: the power chip, the resistance detection end of power chip passes through first resistance ground connection, frequency modulation circuit includes: the power supply comprises a power supply chip, a first capacitor, a second resistor and a first MOS tube, wherein the source electrode of the first MOS tube is grounded, the grid electrode is connected with the load feedback signal input end of the power supply chip through the first capacitor so as to receive a load feedback signal of the power supply, and the drain electrode is connected with the resistance detection end of the power supply chip through the second resistor so as to adjust the resistance value of the resistance detection end according to the load feedback signal and adjust the working frequency of the power supply.
Optionally, the frequency modulation circuit further includes: the high-frequency suppression subcircuit is connected with the grid electrode of the first MOS tube so as to limit the voltage value of the grid electrode of the first MOS tube; the high frequency suppressor circuit includes: the third resistor, the fourth resistor and the first diode; one end of the third resistor is grounded, and the other end of the third resistor is connected with the anode of the first diode; one end of the fourth resistor is grounded, and the other end of the fourth resistor is connected with the grid electrode of the first MOS tube; and the cathode of the first diode is connected with the grid electrode of the first MOS tube.
According to a second aspect, an embodiment of the present invention further provides a switching power supply comprising a frequency modulation circuit as described in the first aspect.
Optionally, the switching power supply further includes: a start-up circuit; the input end of the starting circuit is connected with the high-voltage direct-current signal end of the switching power supply, and the output end of the starting circuit is connected with the power end of the power supply chip and is used for converting the high-voltage direct-current signal into a starting voltage signal of the power supply chip; the start-up circuit includes: the fifth resistor, the sixth resistor, the seventh resistor, the eighth resistor, the transient diode, the zener diode, the second capacitor and the second MOS tube; the input end of the starting circuit is connected with the output end of the starting circuit through the transient diode, the seventh resistor, the eighth resistor and the second capacitor in sequence and is used for converting the high-voltage direct-current signal into a starting voltage signal of the power supply chip; the input end of the starting circuit is connected with the drain electrode of the second MOS tube through a fifth resistor and a sixth resistor in sequence; the source electrode of the second MOS tube is connected with the power end of the power chip and is used for providing a starting voltage signal for the power chip; and the cathode of the voltage stabilizing diode is connected with the grid electrode of the second MOS tube, and the anode of the voltage stabilizing diode is grounded.
Optionally, the switching power supply further includes: a power input module; the input end of the power input module is connected with the input end of an external alternating current power supply, receives an alternating current input voltage signal of the external alternating current power supply, and the output end of the power input module is connected with the input end of the starting circuit and is used for converting the alternating current input voltage signal into the high-voltage direct current signal.
Optionally, the switching power supply further includes: a signal driving circuit; the input end of the signal driving circuit is connected with the signal driving end of the power chip and is used for converting the output driving signals into a first voltage signal and a second voltage signal respectively and outputting the first voltage signal and the second voltage signal.
Optionally, the switching power supply further includes: a power output module; the input end of the power supply output module is connected with the first output end of the signal driving circuit, and converts the first voltage signal into a direct current output voltage signal to be output.
Optionally, the switching power supply further includes: a power supply module; the input end of the power supply module is connected with the second output end of the signal driving circuit, and the output end of the power supply module is connected with the power supply end of the power supply chip through a third diode and is used for converting the second voltage signal into a power supply voltage to supply power for the power supply chip.
Optionally, the switching power supply further includes: a load voltage feedback circuit; the input end of the load voltage feedback circuit is connected with the second output end of the power supply output module, the output end of the load voltage feedback circuit is connected with the load feedback signal input end of the power supply chip, the direct current output voltage signal is converted into a load feedback signal, and the load feedback signal is transmitted to the power supply chip.
Optionally, the switching power supply further includes: a fan control circuit; the input end of the fan control circuit is connected with the output end of the load voltage feedback circuit, the output end of the fan control circuit is connected with the fan of the switching power supply, and the fan is driven to radiate heat.
Optionally, the switching power supply further includes: a protection circuit; the first input end of the protection circuit is connected with the second output end of the power supply output module, the second input end of the protection circuit is connected with the output end of the fan control circuit, and the first output end of the protection circuit is connected with the output end of the starting circuit;
when the input voltage of the first input end and/or the second input end of the protection circuit exceeds the voltage protection value of the protection circuit, the protection circuit is conducted to conduct power-off protection on the switching power supply.
The technical scheme of the invention has the following beneficial effects:
an embodiment of the present invention provides a frequency modulation circuit, which is applied to a switching power supply, the switching power supply including: the power chip, the resistance detection end of power chip passes through first resistance ground connection, and the frequency modulation circuit includes: the source electrode of the first MOS tube is grounded, the grid electrode is connected with the load feedback signal input end of the power supply chip through the first capacitor so as to receive a load feedback signal of the switching power supply, and the drain electrode is connected with the resistance detection end of the power supply chip through the second resistor so as to adjust the resistance value of the resistance detection end according to the load feedback signal and adjust the working frequency of the switching power supply. Through the cooperation of above-mentioned frequency modulation circuit's first resistance, second resistance and first MOS pipe use for switching power supply can be according to the resistance value of the size automatically regulated resistance detection end of load in the use, and then realize the adjustment to switching power supply operating frequency, make switching power supply's operating frequency keep unanimous with the oscillation frequency of the output voltage that the size of the load that switching power supply output carried all the time corresponds, improved switching power supply's availability factor, reduced power loss and prolonged switching power supply's life.
Drawings
FIG. 1 is a block diagram of a FM circuit of a switching power supply according to an embodiment of the present invention;
FIG. 2 is a diagram showing another configuration of a FM circuit of a switching power supply according to an embodiment of the present invention;
FIG. 3 is a block diagram of a start-up circuit of a switching power supply according to an embodiment of the present invention;
fig. 4 shows a block diagram of a switching power supply according to an embodiment of the present invention.
The main reference numerals illustrate:
1-a start-up circuit; 2-a power input module; 3-a signal driving circuit; 4-a power output module; 5-a power supply module; 6-a load voltage feedback circuit; 7-a fan control circuit; 8-a protection circuit; 9-a power chip; a 10-frequency modulation circuit; 11-a high frequency suppressor circuit; r101-a first resistor; r102-a second resistor; r103-third resistance; r104-fourth resistance; r105-first resistance; r106-sixth resistance; r107-seventh resistor; r108-eighth resistor; r110-tenth resistor; d101—a first diode; d102-transient diode; d103—a third diode; ZD 103-zener diode; c101-a first capacitance; c102-a second capacitance; q101-a first MOS tube; q102-a second MOS tube.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; the two components can be directly connected or indirectly connected through an intermediate medium, or can be communicated inside the two components, or can be connected wirelessly or in a wired way. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In addition, the technical features of the different embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
As shown in fig. 1, an embodiment of the present invention provides a frequency modulation circuit 10, where the frequency modulation circuit 10 is applied to a switching power supply, and the switching power supply includes: the power chip 9, the resistance detection end of power chip 9 passes through first resistance R101 ground connection, and frequency modulation circuit 10 includes: the power supply comprises a first capacitor C101, a second resistor R102 and a first MOS tube Q101, wherein the source electrode of the first MOS tube Q101 is grounded, the grid electrode is connected with a load feedback signal input end FB of the power supply chip 9 through the first capacitor C101 so as to receive a load feedback signal of the switch power supply, and the drain electrode is connected with a resistance detection end RT of the power supply chip 9 through the second resistor R102 so as to adjust the resistance value of the resistance detection end RT according to the load feedback signal and adjust the working frequency of the switch power supply.
Through the frequency modulation circuit 10, through the cooperation of the first resistor R101, the second resistor R102 and the first MOS tube Q101, the resistance value of the resistor detection end can be automatically adjusted according to the size of a load in the use process of the switching power supply, and further the adjustment of the working frequency of the switching power supply is realized, so that the working frequency of the switching power supply is always consistent with the oscillation frequency of the output voltage of the switching power supply, the use efficiency of the switching power supply is improved, the power loss is reduced, and the service life of the switching power supply is prolonged.
As shown in fig. 2, in one embodiment, the frequency modulation circuit 10 further includes: the high-frequency suppression subcircuit 11, the high-frequency suppression subcircuit 11 is connected with the grid electrode of the first MOS tube Q101, so as to limit the voltage value of the grid electrode of the first MOS tube Q101;
specifically, the high-frequency suppressor circuit 11 includes: a third resistor R103, a fourth resistor R104, and a first diode D101; one end of the third resistor R103 is grounded, and the other end of the third resistor R103 is connected with the anode of the first diode D101; one end of the fourth resistor R104 is grounded, and the other end of the fourth resistor R is connected with the grid electrode of the first MOS tube Q101; the cathode of the first diode D101 is connected to the gate of the first MOS transistor Q101. The third resistor R103 plays a role in protecting the first diode D101; the load feedback signal is a voltage signal; the first MOS transistor Q101 may be an NMOS transistor.
Specifically, when the load feedback signal input end of the power chip 9 receives the load feedback signal, the load feedback signal will flow to the gate of the first MOS transistor Q101 through the first capacitor C101, and the first MOS transistor Q101 is turned on; here, because the first resistor R101, the first MOS transistor Q101, and the second resistor R102 are in a parallel relationship, the resistance value between the resistance detection end of the power chip 9 and the ground will change along with the conduction strength of the first MOS transistor Q101; when the oscillation frequency of the dc output voltage of the switching power supply is greater than the operating frequency of the switching power supply, the load feedback signal input end of the power supply chip 9 receives a larger load feedback signal (in practical application, the load feedback signal is a voltage feedback signal reflecting the dc output voltage of the switching power supply, the feedback signal of the dc output voltage is changed due to the change of the corresponding load, and the load feedback signal flows to the gate of the first MOS transistor Q101 through the first capacitor C101, so that the first MOS transistor is turned on, the conduction strength is consistent with the magnitude of the load feedback signal, so that the resistance value between the resistance detection end of the power supply chip 9 and the ground is reduced, and the operating frequency of the switching power supply is further improved, so that the oscillation frequency of the dc output voltage of the switching power supply is consistent with that of the switching power supply; when the oscillation frequency of the direct current output voltage of the switching power supply is smaller than the working frequency of the switching power supply, the load feedback signal input end of the power supply chip 9 receives a smaller load feedback signal, the load feedback signal flows to the grid electrode of the first MOS tube Q101 through the first capacitor C101, so that the first MOS tube is conducted, the conduction strength is consistent with the magnitude of the load feedback signal, the resistance value between the resistance detection end of the power supply chip 9 and the ground is increased, and the working frequency of the switching power supply is reduced, so that the oscillation frequency of the load feedback signal is consistent with the oscillation frequency of the direct current output voltage of the switching power supply. Therefore, the function of automatically adjusting the working frequency of the switching power supply according to the change of the load condition is realized, the service efficiency of the switching power supply is improved, the power loss is reduced, and the service life is prolonged.
In practical application, according to the design requirement of the switching power supply, the switching power supply is required to work in a certain frequency range, at this time, if the load feedback signal input end of the power supply chip 9 receives too large load feedback signal, if the working frequency of the switching power supply is adjusted according to the load feedback signal, the working frequency of the switching power supply exceeds the preset working frequency range, the overall performance of the switching power supply is affected, and even the switching power supply is damaged.
In practical applications, the oscillating frequency of the dc output voltage of the switching power supply is affected by the load, and in this application, the current flowing through the load is affected by the size of the load, and the dc output voltage value is also affected by the load being supplied with power by the dc output voltage, so that the oscillating frequency of the load affects the oscillating frequency of the dc output voltage.
Therefore, when the frequency modulation circuit 10 is used, the condition that the switching power supply is damaged due to the fact that the oscillating frequency is too high due to the fact that the resistance between the resistance detection end of the power supply chip 9 and the ground is reduced due to the fact that the conducting force of the first MOS tube Q101 is too high due to the fact that the voltage of the grid electrode is too high is avoided.
The embodiment of the invention also provides a switching power supply, which comprises the frequency modulation circuit 10.
As shown in fig. 3, in an embodiment, the switching power supply further includes: the input end of the starting circuit 1 is connected with a high-voltage direct-current signal end of the switching power supply, and the output end of the starting circuit 1 is connected with the power end of the power chip 9 and is used for converting the high-voltage direct-current signal into a starting voltage signal of the power chip 9;
specifically, the starting circuit 1 includes: a fifth resistor R105, a sixth resistor R106, a seventh resistor R107, an eighth resistor R108, a transient diode D102, a zener diode ZD103, a second capacitor C102 and a second MOS transistor Q102; the input end of the starting circuit 1 is connected with the output end of the starting circuit 1 through a transient diode D102, a seventh resistor R107, an eighth resistor R108 and a second capacitor C102 in sequence, and is used for converting a high-voltage direct-current signal into a starting voltage signal of the power chip 9; the input end of the starting circuit 1 is also connected with the drain electrode of the second MOS tube Q102 through a fifth resistor R105 and a sixth resistor R106 in sequence; the source electrode of the second MOS transistor Q102 is connected with the power end of the power chip 9 and is used for providing a starting voltage signal for the power chip 9; the cathode of the zener diode ZD103 is connected with the grid electrode of the second MOS tube Q102, and the anode is grounded; the transient diode D102 plays a role in undervoltage protection, and when the voltage input by the input end of the starting circuit 1 is too low, the output end of the starting circuit 1 is too low, so that the switching power supply cannot be started, and the whole switching power supply is powered off; the zener diode ZD103 plays a role in stabilizing voltage, when the input voltage of the input end is higher, the voltage transmitted to the gate of the second MOS transistor Q102 is also higher, and at this time, the zener diode ZD103 can make the gate voltage of the second MOS transistor Q102 still be normal voltage, so that the voltage value of the output end of the starting circuit 1 is unchanged.
Specifically, when the input end of the starting circuit 1 receives the high-voltage direct current signal, the transient diode D102 is turned on, the high-voltage direct current signal is reduced, and then the high-voltage direct current signal is divided by the seventh resistor R107 and the eighth resistor R108 and then transmitted to the gate of the second MOS transistor Q102, the second MOS transistor Q102 is turned on to form a starting voltage signal, and the starting voltage signal is transmitted to the power supply end VCC of the power supply chip 9, so that the power supply chip 9 is started.
As shown in fig. 4, in an embodiment, the switching power supply further includes: the power input module 2, the input of power input module 2 is connected with the input of external alternating current power, receives external alternating current power's alternating current input voltage signal, and the output is connected with the input of starting circuit 1 for change alternating current input voltage signal into high voltage direct current signal.
After receiving the external alternating current, the power input module 2 converts the received alternating current input voltage signal of the external alternating current power supply into a high-voltage direct current signal through the first-stage filter LF1 and the second-stage filter LF2 and then through a rectifier bridge BD 1. It should be noted that, the circuit structure of the power input module 2 and the working principle thereof are conventional technical means adopted in the prior art, and those skilled in the art can realize corresponding functions without any doubt based on the disclosure, and no further description is given here.
In an embodiment, the switching power supply further comprises: and the input end of the signal driving circuit 3 is connected with the signal driving end DRV of the power chip 9 and is used for respectively converting the output driving signals into a first voltage signal and a second voltage signal to be output.
The first output end of the signal driving circuit 3 outputs a first voltage signal through a first secondary side B1 of the third transformer T3, and the second output end outputs a second voltage signal through a second secondary side B2 of the third transformer T3. It should be noted that, the circuit structure of the signal driving circuit 3 and the working principle thereof are conventional technical means adopted in the prior art, and those skilled in the art can realize corresponding functions without any doubt based on the disclosure, and no further description is given here.
In an embodiment, the switching power supply further comprises: the input end of the power output module 4 is connected with the first output end of the signal driving circuit 3, and the first voltage signal is converted into a direct current output voltage signal through the rectifying tube D11 and the freewheel tube D12 and is output to a load from the first output end. It should be noted that, the circuit structure of the power output module 4 and the working principle thereof are conventional technical means adopted in the prior art, and those skilled in the art can realize corresponding functions without any doubt based on the disclosure, and no further description is given here.
In an embodiment, the switching power supply further comprises: the input end of the power supply module 5 is connected with the second output end of the signal driving circuit 3, and the output end of the power supply module 5 is connected with the power end VCC of the power chip 9 through the third diode D103 and is used for converting the second voltage signal into the power supply voltage to continuously supply power for the power chip 9. It should be noted that, the circuit structure of the power supply module 5 and the working principle thereof are conventional technical means adopted in the prior art, and those skilled in the art can realize corresponding functions without any doubt based on the disclosure, and no further description is given here.
In an embodiment, the switching power supply further comprises: the input end of the load voltage feedback circuit 6 is connected with the second output end of the power output module 4, the output end is connected with the load feedback signal input end FB of the power chip 9, the direct current output voltage signal is converted into a load feedback signal, and the load feedback signal is transmitted to the power chip 9.
When the load feedback signal received by the load feedback signal input terminal FB is too large or too small, the driving signal received by the input terminal of the logic circuit control signal driving circuit 3 in the power chip 9 will also become large or small, and the first voltage signal output by the first output terminal and the second voltage signal output by the second output terminal will also become large or small. It should be noted that, the circuit structure and the working principle of the load voltage feedback circuit 6 are all conventional technical means adopted in the prior art, and those skilled in the art can realize corresponding functions without any doubt based on the disclosure, and no further description is given here.
In an embodiment, the switching power supply further comprises: and the input end of the fan control circuit 7 is connected with the output end of the load voltage feedback circuit 6, the output end of the fan control circuit 7 is connected with the fan of the switching power supply, and the fan is driven to dissipate heat.
In practical application, the thermistor RTH3 connected with the fan on the fan control circuit 7 is closely adjacent to the inductance coil LI on the power output module 4, and the higher the temperature of the thermistor RTH3, the smaller the resistance, and the larger the voltage between the thermistor RTH3 and one end of the fan. It should be noted that, the circuit structure of the fan control circuit 7 and the working principle thereof are conventional technical means adopted in the prior art, and those skilled in the art can realize corresponding functions without any doubt based on the disclosure, and no further description is given here.
In an embodiment, the switching power supply further comprises: the protection circuit 8, the first input end of the protection circuit 8 is connected with the second output end of the power output module 4, the second input end is connected with the output end of the fan control circuit 7, and the first output end of the protection circuit 8 is connected with the output end of the starting circuit 1.
When the input voltage of the first input end and/or the second input end of the protection circuit 8 exceeds the voltage protection value of the protection circuit 8, the protection circuit 8 is conducted to perform power-off protection on the switching power supply; the voltage protection value is the highest voltage value of the first input terminal and the second input terminal of the protection circuit 8, and of course, the highest voltage value of the first input terminal is different from the highest voltage value of the second input terminal.
Specifically, when the voltage signal at the second output end of the power output module 4 obtained at the first input end of the protection circuit 8 is too large, or the voltage at one end of the thermistor RTH3 connected to the fan is too large, the sixth diode ZD6 is turned on, the third optocoupler U3 is turned on, and since the emitter of the triode of the third optocoupler U3 is grounded, the base OVP is connected to the output end of the starting circuit 1 through the tenth resistor R110, and the output end of the starting circuit 1 is connected to the power end VCC of the power chip 9, so that the power end VCC of the power chip 9 is grounded, thereby resulting in the power-off of the whole switching power supply, and preventing the switching roll power supply from being damaged due to the too large voltage. It should be noted that, the circuit structure of the protection circuit 8 and the working principle thereof are conventional technical means adopted in the prior art, and those skilled in the art can realize corresponding functions without any doubt based on the disclosure, and no further description is given here.
In summary, the power supply process of the switching power supply provided by the invention is as follows:
when the input end of the power input module 2 receives an alternating current input voltage signal of an external alternating current power supply, the alternating current input voltage signal is converted into a high-voltage direct current signal through a first-stage filter LF1 and a second-stage filter LF2, then the high-voltage direct current signal is converted into a starting voltage signal through a starting circuit through a rectifier bridge BD1, the starting voltage signal is transmitted to a power end VCC of the power chip 9 to start the power chip 9, the power chip 9 transmits a driving signal to the signal driving circuit 3 through a signal driving end DRV through an internal logic relation, and the signal driving circuit 3 converts the driving signal into a first voltage signal and a second voltage signal which are respectively output through a first secondary side B1 of a third transformer T3 and a second secondary side B2 of the third transformer T3 of the signal driving circuit 3; the first voltage signal is converted into a direct current output voltage signal through a rectifying tube D11 and a freewheel tube D12 of the power output module 4 and is output; the second voltage signal is converted into a power supply voltage through a power supply module, and then is connected with a power end VCC of the power chip 9 through a third diode D103 to continuously supply power to the power chip 9; because the input end of the load voltage feedback circuit 6 is connected with the second output end of the power output module, the load voltage feedback circuit 6 converts the received direct current output voltage signal into a load feedback signal, the load feedback signal is transmitted to the power chip 9 and the frequency modulation circuit through the load feedback signal input end FB of the power chip 9, the power chip 9 calculates the received load feedback signal through internal logic to control the signal driving end DRV, and controls the magnitude of the driving signal, so as to adjust the first voltage signal and the second voltage signal.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.
Claims (10)
1. A frequency modulation circuit (10) for use in a switching power supply, the switching power supply comprising: the power chip (9), the resistance detection end of power chip (9) is through first resistance (R101) ground connection, its characterized in that, frequency modulation circuit (10) includes: a first capacitor (C101), a second resistor (R102) and a first MOS transistor (Q101), wherein,
the source electrode of the first MOS tube (Q101) is grounded, the grid electrode is connected with the load feedback signal input end of the power supply chip (9) through a first capacitor (C101) so as to receive a load feedback signal of the switching power supply, and the drain electrode is connected with the resistance detection end of the power supply chip (9) through the second resistor (R102) so as to adjust the resistance value of the resistance detection end according to the load feedback signal and adjust the working frequency of the switching power supply;
the frequency modulation circuit further includes: a high-frequency suppression subcircuit (11), wherein the high-frequency suppression subcircuit (11) is connected with the grid electrode of the first MOS tube (Q101) so as to limit the voltage value of the grid electrode of the first MOS tube (Q101);
the high-frequency suppressing sub-circuit (11) includes: a third resistor (R103), a fourth resistor (R104) and a first diode (D101);
one end of the third resistor (R103) is grounded, and the other end of the third resistor is connected with the anode of the first diode (D101);
one end of the fourth resistor (R104) is grounded, and the other end of the fourth resistor is connected with the grid electrode of the first MOS tube (Q101);
the cathode of the first diode (D101) is connected with the grid electrode of the first MOS tube (Q101).
2. A switching power supply, characterized in that it comprises a frequency modulation circuit (10) as claimed in claim 1.
3. The switching power supply of claim 2 further comprising: a start-up circuit (1);
the input end of the starting circuit (1) is connected with the high-voltage direct-current signal end of the switching power supply, and the output end of the starting circuit is connected with the power supply end of the power supply chip (9) and is used for converting the high-voltage direct-current signal into a starting voltage signal of the power supply chip (9);
the starting circuit (1) comprises: a fifth resistor (R105), a sixth resistor (R106), a seventh resistor (R107), an eighth resistor (R108), a transient diode (D102), a zener diode (ZD 103), a second capacitor (C102) and a second MOS tube (Q102);
the input end of the starting circuit (1) is connected with the output end of the starting circuit (1) sequentially through the transient diode (D102), the seventh resistor (R107), the eighth resistor (R108) and the second capacitor (C102), and is used for converting the high-voltage direct-current signal into a starting voltage signal of the power chip (9);
the input end of the starting circuit (1) is connected with the drain electrode of the second MOS tube (Q102) through a fifth resistor (R105) and a sixth resistor (R106) in sequence;
the source electrode of the second MOS tube (Q102) is connected with the power end of the power chip (9) and is used for providing a starting voltage signal for the power chip (9); the grid electrode of the second MOS tube (Q102) is connected between the eighth resistor (R108) and the second capacitor (C102), the cathode of the zener diode (ZD 103) is connected with the grid electrode of the second MOS tube (Q102), and the anode is grounded.
4. A switching power supply as claimed in claim 3, further comprising: a power input module (2);
the input end of the power input module (2) is connected with the input end of an external alternating current power supply, receives an alternating current input voltage signal of the external alternating current power supply, and the output end of the power input module is connected with the input end of the starting circuit (1) and is used for converting the alternating current input voltage signal into the high-voltage direct current signal.
5. A switching power supply as claimed in claim 3, further comprising: a signal driving circuit (3);
the input end of the signal driving circuit (3) is connected with the signal driving end of the power chip (9) and is used for converting the output driving signals into a first voltage signal and a second voltage signal respectively and outputting the first voltage signal and the second voltage signal.
6. The switching power supply of claim 5 further comprising: a power output module (4);
the input end of the power output module (4) is connected with the first output end of the signal driving circuit (3), and converts the first voltage signal into a direct-current output voltage signal to be output.
7. The switching power supply of claim 5 further comprising: a power supply module (5);
the input end of the power supply module (5) is connected with the second output end of the signal driving circuit (3), and the output end of the power supply module is connected with the power end of the power chip (9) through a third diode and is used for converting the second voltage signal into a power supply voltage to supply power for the power chip (9).
8. The switching power supply of claim 6 further comprising: a load voltage feedback circuit (6);
the input end of the load voltage feedback circuit (6) is connected with the second output end of the power supply output module (4), the output end of the load voltage feedback circuit is connected with the load feedback signal input end of the power supply chip (9), the direct current output voltage signal is converted into a load feedback signal, and the load feedback signal is transmitted to the power supply chip (9).
9. The switching power supply of claim 8 further comprising: a fan control circuit (7);
the input end of the fan control circuit (7) is connected with the output end of the load voltage feedback circuit (6), the output end of the fan control circuit is connected with the fan of the switching power supply, and the fan is driven to work so as to radiate heat of the switching power supply.
10. The switching power supply of claim 9 further comprising: a protection circuit (8);
the first input end of the protection circuit (8) is connected with the second output end of the power supply output module (4), the second input end of the protection circuit (8) is connected with the output end of the fan control circuit (7), and the first output end of the protection circuit (8) is connected with the output end of the starting circuit (1);
when the input voltage of the first input end and/or the second input end of the protection circuit (8) exceeds the voltage protection value of the protection circuit (8), the protection circuit (8) is conducted to conduct power-off protection on the switching power supply.
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| CN112506829B (en) * | 2020-12-05 | 2021-11-30 | 青岛鼎信通讯股份有限公司 | Method for eliminating interference of switching power supply of MBUS water meter |
| CN113746338B (en) * | 2021-09-15 | 2023-11-24 | 西安易朴通讯技术有限公司 | Connection circuit and industrial personal computer |
| CN113839369B (en) * | 2021-10-28 | 2024-01-30 | 山东新一代信息产业技术研究院有限公司 | Driver MOS tube parallel protection circuit of robot |
| CN114151375A (en) * | 2021-11-16 | 2022-03-08 | 珠海格力电器股份有限公司 | Fan control device and fan equipment |
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