CN219041633U - Control circuit and constant voltage output switching power supply - Google Patents
Control circuit and constant voltage output switching power supply Download PDFInfo
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- CN219041633U CN219041633U CN202222938580.1U CN202222938580U CN219041633U CN 219041633 U CN219041633 U CN 219041633U CN 202222938580 U CN202222938580 U CN 202222938580U CN 219041633 U CN219041633 U CN 219041633U
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Abstract
The present utility model provides a control circuit comprising: the input end of the output current average value calculation module is coupled with the connecting end of the transistor and the sampling resistor, and the output current average value is calculated based on the voltage drop of the sampling resistor and the sampled inductance current signal thereof; the frequency control module is used for outputting a clock signal for controlling the switching period of the transistor based on the output current average value and determining a frequency reduction point; the over-power control module is used for comparing the output current average value with a set reference signal and outputting an over-power protection signal according to a comparison result; and the input end of the control signal module is coupled with the output ends of the frequency control module and the over-power control module, and the output end of the control signal module is coupled with the control end of the transistor and outputs a control signal for controlling the on-off of the transistor. The utility model realizes that the system frequency reduction point keeps consistent during high-voltage or low-voltage input by calculating the output current average value and limiting the maximum output power of the system and controlling the working frequency of the system based on the output current average value.
Description
Technical Field
The utility model relates to the field of electronics, in particular, but not exclusively, to a control circuit and a constant voltage output switching power supply.
Background
In the conventional constant on-time boost type switching power supply control system, as shown in fig. 1-3, the amplitude frequency (the peak value of the inductor current and the switching frequency of the transistor) and the over-power control are controlled by the output signal of the amplifier, wherein the over-power control is realized by limiting the maximum on-time of the transistor, the peak value of the inductor current is realized by controlling the on-time of the transistor, and when the on-time of the transistor is reduced to a certain proportion of the set maximum on-time, the working frequency of the control system is started to be reduced.
In a boost switching power supply control system, according to energy conservation, the relationship between output power and input voltage is:
where η is the system conversion efficiency and ton is the transistor on-time
When the transistor maximum on-time tonmax is set, the system maximum output power is as follows:
as can be seen from the above equation, the larger the input voltage Vin, the larger the maximum output power point at a given ton max. If the frequency-down is started according to the fixed proportion of tonmax, the larger Vin is, the higher the power point (namely, the maximum output power) corresponding to the frequency-down point is. Such as: when the input voltage is 90Vac, the corresponding over-power protection point is 10W, when the input voltage is 265Vac, the corresponding over-power protection point is 20W, but the over-power protection point required by the actual system is 10W, and if the over-power protection point is 20W, the system is damaged. That is, the existing technical scheme cannot achieve the same over-power protection point no matter the high voltage or the low voltage is input, so that the reliability of the system is affected.
In the prior art, the output power corresponding to the frequency reduction point is increased along with the increase of the input voltage, and if the frequency reduction points of the high-voltage or low-voltage input are required to be consistent, a load compensation method is required. Since the maximum output power increases with an increase in the input voltage, it is generally actually required that the corresponding maximum output power is kept uniform for different input voltages, and thus a complicated compensation method is required.
In view of this, there is an urgent need to design a new control circuit to overcome at least some of the above-mentioned drawbacks of the existing switching power supply.
Disclosure of Invention
Aiming at one or more problems in the prior art, the utility model provides a control circuit and a constant voltage output switching power supply, wherein the system frequency reduction point is kept consistent during high-voltage or low-voltage input by calculating the output current average value of a switching power supply system and limiting the maximum output power of the system and the working frequency of the control system according to the output current average value.
The technical solution for realizing the purpose of the utility model is as follows:
according to an aspect of the present utility model, a control circuit for a constant voltage output switching power supply including an inductance, a transistor, and a sampling resistor connected in series with the transistor, the control circuit comprising:
the input end of the output current average value calculation module is coupled with the connecting end of the transistor and the sampling resistor, and the output current average value of the switching power supply is calculated based on the voltage drop of the sampling resistor and the sampled inductance current signal;
the input end of the frequency control module is coupled with the output end of the output current average value calculation module, and the clock signal for controlling the switching period of the transistor is output based on the output current average value and the frequency reduction point is determined;
the first input end of the over-power control module is coupled with the output end of the output current average value calculation module, the second input end of the over-power control module is connected with a reference signal, and the over-power control module is used for comparing the output current average value with a set reference signal and outputting an over-power protection signal according to a comparison result;
the input end of the control signal module is coupled with the output ends of the frequency control module and the over-power control module, the output end of the control signal module is coupled with the control end of the transistor, and the control signal for controlling the on-off of the transistor is output based on the clock signal and the frequency-reducing point of the switching period of the transistor and the over-power protection signal.
Optionally, the output current average value calculation module includes a proportion operation circuit, and an input end of the proportion operation circuit is connected to the output current average value, and is used for converting the calculated output current average value into a voltage signal or a current signal in proportion and outputting the voltage signal or the current signal.
Optionally, the frequency reducing point in the frequency control module is when the average value of the output current reaches a certain preset proportion of the maximum output current.
Optionally, the frequency reducing point is a point of starting to reduce the operating frequency of the switching power supply.
Optionally, the over-power control module includes a comparator, where a first input end of the comparator is coupled to an output end of the output current average value calculation module, a second input end of the comparator is connected to a reference signal, and an output end of the comparator is coupled to the control signal module and is used for comparing the output current average value with the reference signal.
Optionally, the over-power control module outputs the over-power protection signal when the output current average value is greater than the reference signal.
Optionally, the over-power protection signal includes a control signal for controlling the transistor to be turned off, or a control signal for limiting the output current to a set value.
Optionally, the control circuit includes:
the first input end of the constant voltage control module is connected with the reference voltage, the second input end of the constant voltage control module is connected with the output feedback voltage of the switching power supply, and the constant voltage control module is used for comparing and amplifying the reference voltage and the output feedback voltage and outputting an error amplification signal;
the first input end of the amplitude control module is coupled with the output end of the constant voltage control module, the second input end of the amplitude control module is coupled with the connecting end of the transistor and the sampling resistor, and the output end of the amplitude control module is coupled with the control signal module and is used for comparing the error amplification signal with the voltage drop of the sampling resistor and outputting a control signal for controlling the peak value of the inductance current.
Optionally, the control circuit includes:
the first input end of the constant voltage control module is connected with the reference voltage, the second input end of the constant voltage control module is connected with the output feedback voltage of the switching power supply, and the constant voltage control module is used for comparing and amplifying the reference voltage and the output feedback voltage and outputting an error amplification signal;
the first input end of the amplitude control module is coupled with the output end of the constant voltage control module, and the output end of the amplitude control module is coupled with the control signal module and is used for outputting a control signal for setting the on time of the transistor according to the error amplification signal.
Optionally, the constant voltage control module includes an error amplifier, where a first input end of the error amplifier is connected to a reference voltage, and a second input end of the error amplifier is connected to an output feedback voltage of the switching power supply, and is used to compare the reference voltage with the output feedback voltage to obtain an error amplified signal.
Optionally, the amplitude control module includes a comparator, where a first input end of the comparator is coupled to an output end of the constant voltage control module, a second input end of the comparator is coupled to a connection end of the transistor and the sampling resistor, and an output end of the comparator is coupled to the control signal module, and is used to compare the error amplification signal with a voltage drop of the sampling resistor and output a control signal for controlling a peak value of the inductor current or a control signal for controlling a turn-on time of the transistor.
According to another aspect of the present utility model, a constant voltage output switching power supply includes an inductor, a transistor, a sampling resistor, and a control circuit of any of the above, wherein: the inductor, the transistor and the sampling resistor are sequentially connected in series, the other end of the inductor is connected with input voltage, and the other end of the sampling resistor is grounded; a first input terminal of the control circuit is coupled to the connection terminal of the transistor and the sampling resistor, and a second input terminal
Compared with the prior art, the technical scheme provided by the utility model has the following technical effects:
the control circuit of the utility model obtains the output current average value of the switching power supply through indirect calculation, limits the maximum output power of the system according to the output current average value, realizes that the corresponding maximum output power points are kept consistent when high voltage or low voltage is input, and does not need an additional compensation circuit. Meanwhile, the system frequency is controlled according to the average value of the output current, so that the system frequency reduction point is kept consistent when high-voltage or low-voltage is input, and an additional compensation circuit is not needed.
Drawings
The accompanying drawings are included to provide a further understanding of the utility model, and together with the description serve to explain the embodiments of the utility model, and do not constitute a limitation of the utility model. In the drawings:
fig. 1 shows a schematic configuration of a prior art boost switching power supply system.
Fig. 2 shows a graph of operating frequency versus output power of a prior art boost switching power supply system.
Fig. 3 shows a graph of the over-power protection point versus the input voltage of a prior art boost switching power supply system.
Fig. 4 shows a schematic diagram of the structure of the constant voltage output switching power supply and the control circuit thereof of the present utility model.
Detailed Description
For a further understanding of the present utility model, preferred embodiments of the utility model are described below in conjunction with the examples, but it should be understood that these descriptions are merely intended to illustrate further features and advantages of the utility model, and are not limiting of the claims of the utility model.
The description of this section is intended to be illustrative of only a few exemplary embodiments and the utility model is not to be limited in scope by the description of the embodiments. Combinations of the different embodiments, and alternatives of features from the same or similar prior art means and embodiments are also within the scope of the description and protection of the utility model.
"coupled" or "connected" in the specification includes both direct and indirect connections. An indirect connection is a connection via an intermediary, such as a connection via an electrically conductive medium, such as a conductor, where the electrically conductive medium may contain parasitic inductance or parasitic capacitance, or may be a connection via an intermediary circuit or component described in the embodiments of the specification; indirect connections may also include connections through other active or passive devices, such as through circuits or components such as switches, signal amplification circuits, follower circuits, and the like, that may perform the same or similar functions. "plurality" or "multiple" means two or more.
According to one aspect of the present utility model, a control circuit for a constant voltage output switching power supply. The constant voltage output switching power supply comprises an inductor, a transistor Q1 and a sampling resistor Rcs connected in series with the transistor Q1. In a constant voltage output switching power supply system, the output power po=vout×iout, the output power and the output current are in a proportional relationship, and the output current can directly represent the output power.
According to one embodiment of the utility model, the control circuit comprises an output current average value calculation module, a frequency control module, an over-power control module and a control signal module, wherein:
and an output current average value calculation module, wherein an input end of the output current average value calculation module is coupled with the connecting end of the transistor Q1 and the sampling resistor Rcs, and the output current average value of the switching power supply is calculated based on the voltage drop of the sampling resistor Rcs and the sampled inductance current signal thereof. The inductor charge-discharge time can be obtained according to the inductor current signal. Preferably, the output current average value calculation module comprises a proportional operation circuit, and the input end of the proportional operation circuit is connected with the output current average value and is used for converting the calculated output current average value into a voltage signal or a current signal in proportion and outputting the voltage signal or the current signal.
And the frequency control module is used for controlling the working frequency of the switching power supply. The input end of the output current average value calculating module is coupled with the output end of the output current average value calculating module, and a clock signal for controlling the switching period of the transistor Q1 is output based on the output current average value and a frequency reducing point is determined. That is, the frequency control module is controlled by the output current average. The frequency reducing point is a point of starting to reduce the operating frequency of the switching power supply. In one embodiment, the frequency reducing point is when the average value of the output current reaches a certain preset proportion of the maximum output current. Output voltage x output current average = output power, in constant voltage output switching power supply system, output voltage is unchanged, and then output current average just can directly reflect output power size, sets for the frequency down point according to output current average, is equivalent to setting for the frequency down point according to output power. The frequency reduction is started when the output current average reaches a certain proportion of the maximum output current, which is equivalent to the frequency reduction started from a certain proportion of the maximum output power.
And the over-power control module is used for controlling the maximum output power of the switching power supply. The first input end is coupled with the output end of the output current average value calculation module, the second input end is connected with a reference signal, and the first input end is used for comparing the output current average value with a set reference signal and outputting an over-power protection signal according to a comparison result. In one embodiment, the over-power control module outputs the over-power protection signal when the average output current is greater than the reference signal. Preferably, the over-power control module comprises a comparator, wherein a first input end of the comparator is coupled with an output end of the output current average value calculation module, a second input end of the comparator is connected with a reference signal, and an output end of the comparator is coupled with the control signal module and is used for comparing the output current average value with the reference signal and outputting an over-power protection signal according to a comparison result. Still preferably, the over-power control module includes a comparator, and an input end of the comparator is coupled to an output end of the output current average value calculation module, and when the output current average value is greater than a comparator turning threshold value, the comparator turns over and enters over-power protection. In a preferred embodiment, the over-power protection signal comprises a control signal that controls the transistor to turn off. In another preferred embodiment, the over-power protection signal comprises a control signal defining the output current as a set value.
The input end of the control signal module is coupled with the output ends of the frequency control module and the over-power control module, the output end of the control signal module is coupled with the control end of the transistor Q1, and the control signal for controlling the on-off of the transistor Q1 is output based on the clock signal and the frequency-reducing point of the switching period of the transistor Q1 and the over-power protection signal.
According to another embodiment of the present utility model, as shown in fig. 4, the control circuit includes an output current average value calculation module, a frequency control module, an over-power control module, a constant voltage control module, an amplitude control module, and a control signal module. Wherein:
and an output current average value calculation module, wherein an input end of the output current average value calculation module is coupled with the connecting end of the transistor Q1 and the sampling resistor Rcs, and the output current average value of the switching power supply is calculated based on the voltage drop of the sampling resistor Rcs and the sampled inductance current signal thereof. Preferably, the output current average value calculation module comprises a proportional operation circuit, and the input end of the proportional operation circuit is connected with the output current average value and is used for converting the calculated output current average value into a voltage signal or a current signal in proportion and outputting the voltage signal or the current signal.
And the frequency control module is used for controlling the working frequency of the switching power supply. The input end of the frequency-reducing device is coupled with the output end of the output current average value calculation module, a clock signal for controlling the switching period of the transistor Q1 is output based on the output current average value, and a frequency-reducing point is determined, wherein the frequency-reducing point is a time point for starting to reduce the working frequency of the switching power supply. In one embodiment, the frequency reducing point is when the average value of the output current reaches a certain preset proportion of the maximum output current.
And the over-power control module is used for controlling the maximum output power of the switching power supply. The first input end is coupled with the output end of the output current average value calculation module, the second input end is connected with a reference signal, and the first input end is used for comparing the output current average value with a set reference signal and outputting an over-power protection signal according to a comparison result. In one embodiment, the over-power control module outputs the over-power protection signal when the average output current is greater than the reference signal. Preferably, the over-power control module comprises a comparator, wherein a first input end of the comparator is coupled with an output end of the output current average value calculation module, a second input end of the comparator is connected with a reference signal, and an output end of the comparator is coupled with the control signal module and is used for comparing the output current average value with the reference signal and outputting an over-power protection signal according to a comparison result. In a preferred embodiment, the over-power protection signal comprises a control signal that controls the transistor to turn off. In another preferred embodiment, the over-power protection signal comprises a control signal defining the output current as a set value.
And the constant voltage control module is connected with the reference voltage at a first input end and connected with an output voltage feedback signal of the switching power supply at a second input end, and is used for comparing and amplifying the reference voltage with the output feedback signal and outputting an error amplification signal. Preferably, the constant voltage control module comprises an error amplifier, wherein a first input end of the error amplifier is connected with the reference voltage, and a second input end of the error amplifier is connected with an output voltage feedback signal of the switching power supply, and the error amplifier is used for comparing the reference voltage with the output feedback signal to obtain the error amplification signal.
And the amplitude control module is used for limiting the peak value of the inductive current of the switching power supply. In one embodiment, the first input terminal is coupled to the output terminal of the constant voltage control module, the second input terminal is coupled to the connection terminal of the transistor Q1 and the sampling resistor Rcs, and the output terminal is coupled to the control signal module, for comparing the error amplification signal with the voltage drop Vcs of the sampling resistor Rcs, and outputting a control signal for limiting the peak value of the inductor current. Preferably, the amplitude control module includes a comparator, where a first input end of the comparator is coupled to an output end of the constant voltage control module, a second input end of the comparator is coupled to a connection end of the transistor Q1 and the sampling resistor Rcs, and an output end of the comparator is coupled to the control signal module, and is configured to compare the error amplification signal with the voltage drop Vcs of the sampling resistor Rcs, and output a control signal for controlling a peak value of the inductor current, or a control signal for controlling an on time of the transistor Q1. In another embodiment, the first input terminal is coupled to the output terminal of the constant voltage control module, and the output terminal is coupled to the control signal module, for outputting a control signal for setting the on time of the transistor Q1 according to the error amplification signal.
The input end of the control signal module is coupled with the output ends of the frequency control module, the over-power control module and the amplitude control module, the output end of the control signal module is coupled with the control end of the transistor Q1, and the control signal for controlling the on-off of the transistor Q1 is output based on a clock signal and a frequency reduction point of a switching period of the transistor Q1, an over-power protection signal, and a control signal of an inductance current peak value or a control signal for controlling the on-time of the transistor Q1.
According to another aspect of the present utility model, a constant voltage output switching power supply, as shown in fig. 4, includes an inductor, a transistor Q1, a sampling resistor Rcs, and the control circuit described above. Wherein: the inductor, the transistor Q1 and the sampling resistor Rcs are sequentially connected in series, the other end of the inductor is connected with the input voltage Vin, and the other end of the sampling resistor Rcs is grounded. The first input end of the control circuit is coupled to the connection end of the transistor Q1 and the sampling resistor Rcs, the second input end is connected to the output voltage feedback signal, and the output end is coupled to the control end of the transistor Q1.
The control method realized by the control circuit of the utility model is as follows: the control method is used for the constant voltage output switching power supply, the constant voltage output switching power supply comprises an inductor, a transistor and a sampling resistor connected with the transistor in series, and the control method comprises the following steps:
s1, obtaining voltage drop of a resistor and an inductance current signal sampled by the voltage drop, calculating an output current average value of a switching power supply, and converting the output current average value into a voltage signal or a current signal according to a set proportion.
S2, generating a clock signal for controlling the switching period of the transistor based on the voltage signal or the current signal and setting a frequency-reducing point. Preferably, the frequency reducing point is set when the average value of the output current corresponding to the voltage signal or the current signal reaches the set proportion of the maximum output current, and the working frequency of the switching power supply starts to be reduced.
S3, comparing the voltage signal or the current signal with a reference signal to generate an over-power protection signal. Preferably, when the voltage signal or the current signal is greater than the reference signal, a control signal for controlling the transistor to be turned off is outputted, or a control signal for limiting the output current to a set value is outputted.
S4, comparing an output voltage feedback signal of the switching power supply with a reference voltage to generate an error amplification signal; and generating a control signal for controlling the peak value of the inductive current or a control signal for controlling the on time of the transistor according to the error amplification signal and the voltage drop of the sampling resistor.
S5, generating a control signal for controlling the on-off of the transistor according to the clock signal and the frequency-reducing point of the switching period of the transistor, the over-power protection signal, and the control signal of the peak value of the inductive current or the control signal of the on-time of the transistor.
According to the control circuit, the control method and the constant-voltage output switching power supply, the system frequency reduction point is kept consistent during high-voltage or low-voltage input by calculating the output current average value of the switching power supply system and limiting the maximum output power of the system and the working frequency of the control system according to the output current average value.
It will be appreciated by those skilled in the art that the logic controls of the "high" and "low", "set" and "reset", "and" or "," in-phase input "and" anti-phase input "among the logic controls described in the specification or drawings may be interchanged or changed, and that the same functions or purposes as those of the above embodiments may be achieved by adjusting the subsequent logic controls.
The description and applications of the present utility model herein are illustrative and are not intended to limit the scope of the utility model to the embodiments described above. The relevant descriptions of effects, advantages and the like in the description may not be presented in practical experimental examples due to uncertainty of specific condition parameters or influence of other factors, and the relevant descriptions of effects, advantages and the like are not used for limiting the scope of the utility model. Variations and modifications of the embodiments disclosed herein are possible, and alternatives and equivalents of the various components of the embodiments are known to those of ordinary skill in the art. It will be clear to those skilled in the art that the present utility model may be embodied in other forms, structures, arrangements, proportions, and with other assemblies, materials, and components, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the utility model.
Claims (12)
1. A control circuit for a constant voltage output switching power supply comprising an inductor, a transistor, and a sampling resistor in series with the transistor, the control circuit comprising:
the input end of the output current average value calculation module is coupled with the connecting end of the transistor and the sampling resistor, and the output current average value of the switching power supply is calculated based on the voltage drop of the sampling resistor and the sampled inductance current signal;
the input end of the frequency control module is coupled with the output end of the output current average value calculation module, and the clock signal for controlling the switching period of the transistor is output based on the output current average value and the frequency reduction point is determined;
the first input end of the over-power control module is coupled with the output end of the output current average value calculation module, the second input end of the over-power control module is connected with a reference signal, and the over-power control module is used for comparing the output current average value with a set reference signal and outputting an over-power protection signal according to a comparison result;
the input end of the control signal module is coupled with the output ends of the frequency control module and the over-power control module, the output end of the control signal module is coupled with the control end of the transistor, and the control signal for controlling the on-off of the transistor is output based on the clock signal and the frequency-reducing point of the switching period of the transistor and the over-power protection signal.
2. The control circuit according to claim 1, wherein the output current average value calculation module comprises a proportional operation circuit, and an input end of the proportional operation circuit is connected to the output current average value and is used for converting the calculated output current average value into a voltage signal or a current signal in proportion and outputting the voltage signal or the current signal.
3. The control circuit of claim 1, wherein the frequency down point in the frequency control module is when the average output current reaches a certain preset ratio of the maximum output current.
4. A control circuit according to claim 1 or 3, wherein the frequency-reducing point is a point at which the operation frequency of the switching power supply starts to be reduced.
5. The control circuit of claim 1, wherein the over-power control module comprises a comparator having a first input coupled to an output of the output current average calculation module, a second input coupled to a reference signal, and an output coupled to the control signal module for comparing the output current average to the reference signal.
6. The control circuit of claim 1 or 5, wherein the over-power control module outputs the over-power protection signal when the output current average is greater than the reference signal.
7. A control circuit according to claim 1 or 6, wherein the over-power protection signal comprises a control signal that controls the transistor to turn off, or a control signal that limits the output current to a set value.
8. The control circuit of claim 1, wherein the control circuit comprises:
the first input end of the constant voltage control module is connected with the reference voltage, the second input end of the constant voltage control module is connected with the output feedback voltage of the switching power supply, and the constant voltage control module is used for comparing and amplifying the reference voltage and the output feedback voltage and outputting an error amplification signal;
the first input end of the amplitude control module is coupled with the output end of the constant voltage control module, the second input end of the amplitude control module is coupled with the connecting end of the transistor and the sampling resistor, and the output end of the amplitude control module is coupled with the control signal module and is used for comparing the error amplification signal with the voltage drop of the sampling resistor and outputting a control signal for limiting the peak value of the inductive current.
9. The control circuit of claim 1, wherein the control circuit comprises:
the first input end of the constant voltage control module is connected with the reference voltage, the second input end of the constant voltage control module is connected with the output feedback voltage of the switching power supply, and the constant voltage control module is used for comparing and amplifying the reference voltage and the output feedback voltage and outputting an error amplification signal;
the first input end of the amplitude control module is coupled with the output end of the constant voltage control module, and the output end of the amplitude control module is coupled with the control signal module and is used for outputting a control signal for setting the on time of the transistor according to the error amplification signal.
10. The control circuit according to claim 8 or 9, wherein the constant voltage control module comprises an error amplifier, a first input terminal of the error amplifier being connected to a reference voltage, and a second input terminal being connected to an output feedback voltage of the switching power supply, for comparing the reference voltage with the output feedback voltage to obtain the error amplified signal.
11. The control circuit of claim 8, wherein the amplitude control module comprises a comparator having a first input coupled to an output of the constant voltage control module, a second input coupled to a connection of the transistor to the sampling resistor, and an output coupled to the control signal module for comparing the error amplification signal with a voltage drop across the sampling resistor and outputting a control signal for controlling a peak value of the inductor current or a control signal for controlling an on-time of the transistor.
12. A constant voltage output switching power supply comprising an inductor, a transistor, a sampling resistor, and a control circuit as claimed in any one of claims 1 to 11, wherein: the inductor, the transistor and the sampling resistor are sequentially connected in series, the other end of the inductor is connected with input voltage, and the other end of the sampling resistor is grounded; the first input end of the control circuit is coupled with the connecting end of the transistor and the sampling resistor, the second input end of the control circuit is connected with the output feedback voltage, and the output end of the control circuit is coupled with the control end of the transistor.
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| CN202222938580.1U CN219041633U (en) | 2022-11-04 | 2022-11-04 | Control circuit and constant voltage output switching power supply |
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| CN202222938580.1U CN219041633U (en) | 2022-11-04 | 2022-11-04 | Control circuit and constant voltage output switching power supply |
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