CN113809927B - Transmission structure and transmission method for constant voltage control error signal of flyback power supply - Google Patents
Transmission structure and transmission method for constant voltage control error signal of flyback power supply Download PDFInfo
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- CN113809927B CN113809927B CN202111017912.6A CN202111017912A CN113809927B CN 113809927 B CN113809927 B CN 113809927B CN 202111017912 A CN202111017912 A CN 202111017912A CN 113809927 B CN113809927 B CN 113809927B
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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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/3353—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter
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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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- 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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Abstract
The invention relates to a transmission structure and a transmission method of a flyback power supply constant voltage control error signal, wherein the transmission structure comprises a first side used for connecting an input voltage, a second side used for connecting a load and a feedback circuit; the first side comprises a pulse width control circuit; the pulse width control circuit comprises a pulse width control chip; the second side is provided with an error signal amplifying circuit; the error signal amplifying circuit comprises a three-terminal adjustable voltage stabilizing device; the feedback circuit comprises an optical coupler; the light emitting side of the optical coupler is connected in parallel with the first end and the second end of the three-end adjustable voltage stabilizing device; one end of the photosensitive side of the optical coupler is connected to the feedback signal input pin, and the photosensitive side of the optical coupler is connected in series to a loop between the working power supply pin and the grounding end; the standby current of the pulse width control chip is positively correlated with the photosensitive side current of the optocoupler. When the pulse width control chip is in standby, no continuous current is generated in a loop where a pull-down resistor in the pulse width control chip is located, so that the standby power consumption is reduced to the minimum.
Description
Technical Field
The invention relates to the field of analog power management integrated chips, in particular to a transmission device and a transmission method for a flyback power supply constant voltage control error signal.
Background
Fig. 1 is a schematic diagram of a circuit structure of the prior art. As shown in fig. 1, in the prior art, a flyback power constant voltage control apparatus includes an isolation transformer T, a primary side of the isolation transformer T is used for inputting a voltage, a secondary side of the isolation transformer T is used for connecting a load, and an optocoupler. The optocoupler includes a light emitting side OC2 and a light sensitive side OC 1. The light emitting side OC2 includes light emitting diodes. The photo side OC1 includes a photo transistor.
The secondary side is provided with an error signal amplification circuit. The error signal amplifying circuit comprises a three-terminal adjustable voltage stabilizing chip U2 with the model number of TL 431. The series circuit of the first resistor R1 and the second resistor R2 samples the output voltage. The voltage of the common end of the first resistor R1 and the second resistor R2 is used as the reference voltage of the three-terminal adjustable voltage-stabilizing chip U2. The anode end of the three-terminal adjustable voltage-stabilizing chip U2 is grounded, the cathode end is connected to the cathode of the light-emitting diode, and the anode of the light-emitting diode is connected to the voltage output end VBUS through the third resistor R3.
The primary side is provided with a pulse width control chip U1, and the pulse width control chip U1 includes a feedback signal input pin FB and a working power supply pin VDD. The emitter of the phototriode is connected with the grounding end, and the collector of the phototriode is connected with the feedback signal input pin FB. Inside the pulse width control chip U1, the feedback signal input pin FB is connected to the operating power supply pin VDD via a pull-up resistor Rup.
When an error current signal is generated between the cathode end and the anode end of the three-end adjustable voltage-stabilizing chip U2, a current signal is also generated in the light-emitting diode connected in series with the cathode end and the anode end of the three-end adjustable voltage-stabilizing chip U2, the photosensitive side OC1 of the optical coupler receives the error current signal, and then the signal output by the pulse width control chip U1 is adjusted, the voltage duty ratio of the primary side of the isolation transformer T is adjusted, and the closed-loop constant voltage control of the system is realized.
In the prior art shown in fig. 1, when the system is in a standby state, the current flowing through the light emitting diode reaches the maximum, and accordingly, the phototransistor is also coupled to generate the maximum current, and a continuous current is also generated in a loop formed by the operating power supply pin VDD, the pull-up resistor Rup, the feedback signal input pin FB, and the phototransistor to the ground terminal of the pulse width control chip U1, so that when the system is in a standby state and is in an idle state, a continuous current path is formed inside the pulse width control chip U1 on the primary side, and continuous static power consumption is generated. With the implementation of new power consumption standards and the demands of users, standby power consumption requirements are lower and lower (for example, less than 20mW), and the prior art limits the minimum standby power consumption.
Disclosure of Invention
Aiming at the defects of the prior art, the invention discloses a transmission structure and a transmission method of a flyback power supply constant voltage control error signal.
The technical scheme adopted by the invention is as follows:
a transmission structure of a flyback power supply constant voltage control error signal is disclosed, wherein the flyback power supply comprises a first side used for connecting an input voltage, a second side used for connecting a load and a feedback circuit;
the first side comprises a pulse width control circuit; the pulse width control circuit comprises a pulse width control chip; the pulse width control chip comprises a feedback signal input pin and a working power supply pin;
the second side is provided with an error signal amplifying circuit; the error signal amplifying circuit comprises a three-terminal adjustable voltage stabilizing device; the three-terminal adjustable voltage regulator comprises a control terminal, a first terminal and a second terminal, the error signal amplifying circuit samples an electric signal at a load to be used as a reference voltage of the control terminal, and the reference voltage input by the control terminal is in positive correlation with a current between the first terminal and the second terminal;
the feedback circuit comprises an optocoupler; the light emitting side of the optical coupler is connected in parallel with the first end and the second end of the three-end adjustable voltage stabilizing device; one end of the photosensitive side of the optical coupler is connected to the feedback signal input pin, and the photosensitive side of the optical coupler is connected in series to a loop between the working power supply pin and the grounding end; the standby current of the pulse width control chip is positively correlated with the photosensitive side current of the optocoupler.
The further technical scheme is as follows: the error signal amplifying circuit comprises a first resistor and a second resistor which are connected between the voltage output end and the grounding end and are connected in series with each other; the control end of the three-end adjustable voltage stabilizing device is connected to the common end of the first resistor and the second resistor; the first end of the three-end adjustable voltage stabilizing device is connected to the voltage output end through a third resistor, and the second end of the three-end adjustable voltage stabilizing device is connected to the grounding end.
The further technical scheme is as follows: the three-end adjustable voltage stabilizing device is a three-end adjustable voltage stabilizing chip with the model number of TL 431; the reference voltage end of the three-end adjustable voltage stabilizing chip is used as a control end and is connected to the common end of the first resistor and the second resistor; the cathode end of the three-end adjustable voltage-stabilizing chip is connected to the voltage output end through a third resistor, and the anode end of the three-end adjustable voltage-stabilizing chip is connected to the grounding end.
The further technical scheme is as follows: the light emitting side of the optocoupler comprises a light emitting diode; the anode of the light emitting diode is connected to the first end of the three-end adjustable voltage stabilizing device through a fifth resistor; the cathode terminal of the light emitting diode is connected to the ground terminal.
The further technical scheme is as follows: the photosensitive side of the optocoupler comprises a phototriode; the collector of the phototriode is connected with the working power supply pin; an emitter of the phototriode is connected to the feedback signal input pin; in the pulse width control chip, a feedback signal input pin is connected to a ground terminal through a pull-down resistor.
The further technical scheme is as follows: the photosensitive side of the optocoupler comprises a phototriode; the collector of the phototriode is connected with the feedback signal input pin, and the emitter of the phototriode is connected with the ground terminal; the pulse width control chip comprises a mirror current source circuit; the current input end of the mirror current source circuit is connected to the working power supply pin, the input loop of the mirror current source circuit is connected to the feedback signal input pin, and the output loop of the mirror current source circuit is connected to the grounding end through the pull-down resistor.
The further technical scheme is as follows: the flyback power supply also comprises an isolation transformer; the primary side of the isolation transformer inputs an input voltage superposed with the pulse width modulation signal output by the pulse width control circuit; the secondary side of the isolation transformer is connected with a load; the error signal amplifying circuit is connected to the secondary side of the transformer and samples the output voltage.
A method for transmitting a flyback power supply constant voltage control error signal as described in any one of the above, comprising the following steps:
when the load power is reduced, the output voltage is increased; the error signal amplifying circuit samples the output voltage and increases the reference voltage at the control end of the three-end adjustable voltage stabilizing device; the current between the first end and the second end of the three-end adjustable voltage stabilizing device is increased; further reducing the current flowing through the light-emitting side of the optical coupler; when the current of the photosensitive side of the optocoupler is reduced, the potential of a feedback signal input pin of the pulse width control chip is reduced, so that the duty ratio of the pulse width voltage signal of the first side is reduced; the output voltage of the second side is reduced to realize constant voltage control;
when the load power is increased, the output voltage is reduced; the error signal amplifying circuit samples the output voltage and reduces the reference voltage at the control end of the three-end adjustable voltage stabilizing device; the current between the first end and the second end of the three-end adjustable voltage stabilizing device is reduced; further increasing the current of the light emitting side flowing through the optical coupler; when the current of the photosensitive side of the optical coupler is increased, the potential of a feedback signal input pin of the pulse width control chip is increased, so that the duty ratio of the pulse width voltage signal of the first side is increased; the output voltage of the second side increases to realize constant voltage control.
According to the transmission method of the constant voltage control error signal of the flyback power supply, when the load power is 0, the output voltage is the maximum value; the error signal amplifying circuit samples the output voltage and enables the reference voltage at the control end of the three-end adjustable voltage stabilizing device to be maximum; the current between the first end and the second end of the three-end adjustable voltage stabilizing device is the maximum value; further, the current of the light-emitting side flowing through the optical coupler is 0; the photosensitive side current of the optical coupler is 0, namely the current in a loop between a working power supply pin and a grounding end is 0, the standby current of the pulse width control chip is 0, and no standby power consumption exists.
The invention has the following beneficial effects:
the invention changes the structure for sampling the output voltage by changing the connection method of the light-emitting side of the optical coupler in the feedback circuit, correspondingly changes the connection method of the photosensitive side of the optical coupler, and changes the loop generated by the standby current in the pulse width control chip, so that when the output voltage is in no-load, the current of the light-emitting side of the optical coupler is reduced, the current of the photosensitive side is correspondingly reduced, and the loop of the pull-down resistor in the pulse width control chip is free from continuous current generation, thereby reducing the standby power consumption to the lowest.
The flyback power supply has the advantages of ingenious design and simple circuit structure, does not influence the original constant voltage control function of the flyback power supply, and has strong practicability on the basis.
Drawings
Fig. 1 is a schematic diagram of a circuit structure of the prior art.
Fig. 2 is a schematic diagram of a circuit structure according to embodiment 1 of the present invention.
Fig. 3 is a schematic diagram of a circuit structure according to embodiment 2 of the present invention.
Detailed Description
The following description of the embodiments of the present invention refers to the accompanying drawings.
Fig. 2 and 3 show a specific embodiment of the solution according to the invention.
Fig. 2 is a schematic diagram of a circuit structure according to embodiment 1 of the present invention. As shown in fig. 2, the flyback power supply includes an isolation transformer T. The primary side of the transformer T is used for connecting input voltage, the secondary side of the transformer T is used for connecting a load, and the feedback circuit feeds back an electric signal on the load side to the primary side.
The primary side includes a pulse width control chip U1. The pulse width control chip U1 has a comparator, a flip-flop, and the like built therein. The pulse width control chip U1 includes a feedback signal input pin FB, an operating power supply pin VDD, and a switching signal output pin GATE. The operating power supply is connected to the operating power supply pin VDD through a diode D1 that functions as a rectifier. Inside the pulse width control chip U1, the feedback signal input pin FB is connected to the ground terminal through a pull-down resistor Rdn. The primary side also includes a field effect transistor T1. The source of the fet T1 is connected to ground via a fourth resistor R4. The drain of the fet T1 is connected to a second input terminal on the primary side of the transformer T1. A first input of the primary side of the transformer T1 is used for connecting the input voltage VIN.
The secondary side includes an error signal amplification circuit. The error signal amplifying circuit comprises a three-terminal adjustable voltage stabilizing device. In this embodiment, the three-terminal adjustable voltage regulator device is a three-terminal adjustable voltage regulator chip U2 with model number TL 431. Other types of chips or amplifying circuits with the same function can be used for the three-terminal adjustable voltage stabilizing device. The error signal amplifying circuit further includes a first resistor R1 and a second resistor R2 connected in series. The first end of the first resistor R1 is connected to the voltage output terminal VBUS, the second end of the first resistor R1 is connected to the first end of the second resistor R2, and the second end of the second resistor R2 is connected to ground. The reference voltage end of the three-end adjustable voltage-stabilizing chip U2 is connected to the common end of the first resistor R1 and the second resistor R2 as a control end. The cathode terminal of the three-terminal adjustable voltage regulation chip U2 is connected to the voltage output terminal VBUS through a third resistor R3, and the anode terminal of the three-terminal adjustable voltage regulation chip U2 is connected to the ground terminal.
The feedback circuit includes an optocoupler. The optocoupler includes a light emitting side OC2 and a light sensitive side OC 1. The light emitting side OC2 comprises light emitting diodes. The photo side OC1 includes a photo transistor. The anode of the light emitting diode is connected to a first terminal of a fifth resistor R5. The second end of the fifth resistor R5 is connected to the cathode end of the three-terminal adjustable voltage regulation chip U2. The anode of the light emitting diode is grounded. The collector of the phototriode is connected to the working power supply pin VDD, and the emitter of the phototriode is connected to the feedback signal input pin FB. Inside the pulse width control chip U1, the feedback signal input pin FB is connected to ground through a pull-down resistor Rdn. Also due to such a connection method, the standby power consumption of the pulse width control chip U1 mainly occurs on the pull-down resistor Rdn.
In the circuit shown in fig. 2, the output voltage of the secondary side of the isolation transformer T passes through the optical coupler of the feedback circuit, and the electrical signal is fed back to the feedback signal input pin FB of the pulse width control chip U1, and the pulse width control chip U1 controls the voltage duty ratio of the primary side of the isolation transformer T, that is, controls the input power, by controlling the high-low level output by the switching signal output pin GATE, so that when the flyback power supply normally operates, the closed-loop constant voltage control can be realized by the feedback circuit.
When the flyback power supply is in standby, when the load power is 0, the output voltage is the maximum value, the series circuit formed by the first resistor R1 and the second resistor R2 samples the output voltage, at this time, the reference voltage VREF at the control end of the three-end adjustable voltage stabilization chip U2 is the maximum value, the current between the cathode end and the anode end of the three-end adjustable voltage stabilization chip U2 is the maximum value, when the resistance value of the fifth resistor R5 is large enough, the current in the light emitting diode is 0, the current from the collector electrode to the emitter electrode of the phototriode is 0, then in a loop formed by the working power supply pin VDD, the phototriode, the feedback signal input pin FB, the pull-down resistor Rdn to the ground end, the current is 0, the standby current of the pulse width control chip is 0, and no static standby power consumption exists.
Fig. 3 is a schematic diagram of a circuit structure according to embodiment 2 of the present invention.
As shown in fig. 3, in embodiment 2, the circuit configuration of the secondary side of the isolation transformer T is the same as that of embodiment 1. On the primary side of the isolation transformer T, the collector of the phototransistor is connected to the feedback signal input pin FB, and the emitter of the phototransistor is grounded. A second capacitor C2 is also connected in parallel between the collector and emitter of the phototransistor. And a mirror current source circuit is arranged in the pulse width control chip U1, the current input end of the mirror current source circuit is connected to the working power supply pin VDD, the input loop of the mirror current source circuit is connected to the feedback signal input pin FB, and the output loop of the mirror current source circuit is connected to the ground end through a pull-down resistor Rdn. Since the pull-down resistor Rdn generates a loop between the operating power pin VDD and the ground terminal, if the pulse width control chip U1 has a static power consumption inside, it is mainly reflected on the pull-down resistor Rdn.
When the flyback power supply normally works, closed-loop constant-voltage control can be realized through the feedback circuit, and the principle is not repeated. When the standby state is realized, when the load power is 0, the output voltage is the maximum value, the series circuit formed by the first resistor R1 and the second resistor R2 samples the output voltage, the reference voltage VREF at the control end of the three-terminal adjustable voltage stabilization chip U2 is the maximum value, the current between the cathode end and the anode end of the three-terminal adjustable voltage stabilization chip U2 is the maximum value, when the resistance value of the fifth resistor R5 is large enough, the current in the light emitting diode is 0, the current from the collector to the emitter of the phototriode is 0, the current in a loop formed by the working power supply pin VDD, the input loop of the mirror current source circuit, the feedback signal input pin FB, the collector of the phototriode, and the emitter to the ground of the phototriode is 0, and according to the basic principle of the mirror current source circuit, the output loop current of the mirror current source circuit is also 0, the working power supply pin VDD, In a loop formed by an output loop of the mirror current source circuit and a pull-down resistor Rdn to a grounding end, the current is 0, the standby current of the pulse width control chip is 0, and no static standby power consumption exists.
In summary, the present invention discloses a transmission structure for a constant voltage control error signal of a flyback power supply, wherein the flyback power supply includes a first side for connecting an input voltage, a second side for connecting a load, and a feedback circuit. The first side includes a pulse width control circuit. The pulse width control circuit comprises a pulse width control chip. The pulse width control chip comprises a feedback signal input pin and a working power supply pin. The level of the feedback signal input pin can influence the level output by the switching signal output pin GATE of the pulse width control chip, so as to control the switching device to be switched on and switched off, and when such a signal is superposed on the input voltage, the input power of the first side can be controlled.
The second side is provided with an error signal amplifying circuit. The error signal amplifying circuit comprises a three-terminal adjustable voltage stabilizing device. The three-terminal adjustable voltage regulator comprises a control terminal, a first terminal and a second terminal, wherein the error signal amplifying circuit samples an electric signal at a load as a reference voltage of the control terminal, and the reference voltage input by the control terminal is in positive correlation with a current between the first terminal and the second terminal.
The feedback circuit includes an optocoupler. The light emitting side of the optical coupler is connected in parallel with the first end and the second end of the three-end adjustable voltage stabilizing device. In the transmission structure, the light emitting side of the optical coupler is connected in parallel with the first end and the second end of the three-end adjustable voltage stabilizing device, and the photosensitive side of the optical coupler is connected in series in a loop between the working power supply pin and the grounding end. The standby current of the pulse width control chip is positively correlated with the photosensitive side current of the optocoupler. Such a relationship of positive current correlation can be realized by a series circuit as shown in embodiment 1, a mirror current source circuit as shown in embodiment 2, or other similar circuit configurations. The standby power consumption of the pulse width control chip is related to the standby current, and when the standby current is minimum, the standby power consumption can be reduced to the minimum.
The foregoing description is illustrative of the present invention and is not to be construed as limiting thereof, as the invention is defined by the appended claims, as they may be modified in all forms without departing from the essential structures of the invention.
Claims (9)
1. A transmission structure of a constant voltage control error signal of a flyback power supply comprises a first side used for connecting an input voltage, a second side used for connecting a load and a feedback circuit; the method is characterized in that:
the first side comprises a pulse width control circuit; the pulse width control circuit comprises a pulse width control chip; the pulse width control chip comprises a feedback signal input pin and a working power supply pin;
the second side is provided with an error signal amplifying circuit; the error signal amplifying circuit comprises a three-terminal adjustable voltage stabilizing device; the three-terminal adjustable voltage regulator comprises a control terminal, a first terminal and a second terminal, the error signal amplifying circuit samples an electric signal at a load to be used as a reference voltage of the control terminal, and the reference voltage input by the control terminal is in positive correlation with a current between the first terminal and the second terminal;
the feedback circuit comprises an optical coupler; the light emitting side of the optical coupler is connected in parallel with the first end and the second end of the three-end adjustable voltage stabilizing device; one end of the photosensitive side of the optocoupler is connected to the feedback signal input pin, and the photosensitive side of the optocoupler is connected in series to a loop between the working power supply pin and the ground terminal; the standby current of the pulse width control chip is positively correlated with the photosensitive side current of the optocoupler.
2. The transmission structure of the flyback power supply constant voltage control error signal as claimed in claim 1, wherein: the error signal amplifying circuit comprises a first resistor and a second resistor which are connected between the voltage output end and the grounding end and are connected in series with each other; the control end of the three-end adjustable voltage stabilizing device is connected to the common end of the first resistor and the second resistor; the first end of the three-end adjustable voltage stabilizing device is connected to the voltage output end through the third resistor, and the second end of the three-end adjustable voltage stabilizing device is connected to the grounding end.
3. The transmission structure of the flyback power supply constant voltage control error signal as claimed in claim 2, wherein: the three-end adjustable voltage stabilizing device is a three-end adjustable voltage stabilizing chip with the model number of TL 431; the reference voltage end of the three-end adjustable voltage stabilizing chip is used as a control end and is connected to the common end of the first resistor and the second resistor; the cathode end of the three-end adjustable voltage-stabilizing chip is connected to the voltage output end through a third resistor, and the anode end of the three-end adjustable voltage-stabilizing chip is connected to the grounding end.
4. The transmission structure of the flyback power supply constant voltage control error signal as claimed in claim 1, wherein: the light emitting side of the optocoupler comprises a light emitting diode; the anode of the light emitting diode is connected to the first end of the three-end adjustable voltage stabilizing device through a fifth resistor; the cathode terminal of the light emitting diode is connected to the ground terminal.
5. The transmission structure of the flyback power supply constant voltage control error signal as claimed in claim 1, wherein: the photosensitive side of the optocoupler comprises a phototriode; the collector of the phototriode is connected with the working power supply pin; an emitter of the phototriode is connected to the feedback signal input pin; in the pulse width control chip, a feedback signal input pin is connected to a ground terminal through a pull-down resistor.
6. The transmission structure of the flyback power supply constant voltage control error signal as claimed in claim 1, wherein: the photosensitive side of the optocoupler comprises a phototriode; the collector of the phototriode is connected with the feedback signal input pin, and the emitter of the phototriode is connected with the ground terminal; the pulse width control chip comprises a mirror current source circuit; the current input end of the mirror current source circuit is connected to the working power supply pin, the input loop of the mirror current source circuit is connected to the feedback signal input pin, and the output loop of the mirror current source circuit is connected to the grounding end through the pull-down resistor.
7. The transmission structure of the flyback power supply constant voltage control error signal as claimed in claim 1, wherein: the flyback power supply also comprises an isolation transformer; the primary side of the isolation transformer inputs an input voltage superposed with the pulse width modulation signal output by the pulse width control circuit; the secondary side of the isolation transformer is connected with a load; the error signal amplifying circuit is connected to the secondary side of the transformer and samples the output voltage.
8. A transmission method of a flyback power supply constant voltage control error signal, wherein the transmission structure of the flyback power supply constant voltage control error signal according to any one of claims 1 to 7 is adopted, characterized by comprising the following processes:
when the load power is reduced, the output voltage is increased; the error signal amplifying circuit samples the output voltage and increases the reference voltage at the control end of the three-end adjustable voltage stabilizing device; the current between the first end and the second end of the three-end adjustable voltage stabilizing device is increased; further reducing the current flowing through the light-emitting side of the optical coupler; when the current of the photosensitive side of the optocoupler is reduced, the potential of a feedback signal input pin of the pulse width control chip is reduced, so that the duty ratio of the pulse width voltage signal of the first side is reduced; the output voltage of the second side is reduced to realize constant voltage control;
when the load power is increased, the output voltage is reduced; the error signal amplifying circuit samples the output voltage and reduces the reference voltage at the control end of the three-end adjustable voltage stabilizing device; the current between the first end and the second end of the three-end adjustable voltage stabilizing device is reduced; further increasing the current of the light emitting side flowing through the optical coupler; when the current of the photosensitive side of the optical coupler is increased, the potential of a feedback signal input pin of the pulse width control chip is increased, so that the duty ratio of the pulse width voltage signal of the first side is increased; the output voltage of the second side increases to realize constant voltage control.
9. A transmission method of a flyback power supply constant voltage control error signal, wherein a transmission structure of a flyback power supply constant voltage control error signal according to any one of claims 1 to 7 is adopted, characterized in that: when the load power is 0, the output voltage is the maximum value; the error signal amplifying circuit samples the output voltage and enables the reference voltage at the control end of the three-end adjustable voltage stabilizing device to be maximum; the current between the first end and the second end of the three-end adjustable voltage stabilizing device is the maximum value; further, the current of the light-emitting side flowing through the optical coupler is 0; the photosensitive side current of the optical coupler is 0, namely the current in a loop between a working power supply pin and a grounding end is 0, the standby current of the pulse width control chip is 0, and no standby power consumption exists.
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| CN102566635A (en) * | 2010-12-15 | 2012-07-11 | 立锜科技股份有限公司 | Parallel regulator, flyback converter and control method of output feedback thereof |
| CN104253954A (en) * | 2014-09-17 | 2014-12-31 | 广州视源电子科技股份有限公司 | Low-power-consumption constant-current and backlight control circuit and television |
| CN108448876A (en) * | 2018-03-30 | 2018-08-24 | 成都芯源系统有限公司 | Circuit and method for reducing light load power consumption |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7023005B2 (en) * | 2001-12-21 | 2006-04-04 | Texas Instruments Incorporated | Gain compensation for optocoupler feedback circuit |
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2021
- 2021-08-31 CN CN202111017912.6A patent/CN113809927B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102566635A (en) * | 2010-12-15 | 2012-07-11 | 立锜科技股份有限公司 | Parallel regulator, flyback converter and control method of output feedback thereof |
| CN104253954A (en) * | 2014-09-17 | 2014-12-31 | 广州视源电子科技股份有限公司 | Low-power-consumption constant-current and backlight control circuit and television |
| CN108448876A (en) * | 2018-03-30 | 2018-08-24 | 成都芯源系统有限公司 | Circuit and method for reducing light load power consumption |
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| CN113809927A (en) | 2021-12-17 |
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