CN115664163A - Control circuit, control method and constant-voltage output switching power supply - Google Patents
Control circuit, control method and constant-voltage output switching power supply Download PDFInfo
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Abstract
The present invention 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 inductive current signal; the frequency control module outputs a clock signal for controlling the switching period of the transistor based on the average value of the output current and determines a frequency reduction point; the over-power control module is used for comparing the average value of the output current 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 overpower control module, and the output end of the control signal module is coupled with the control end of the transistor to output a control signal for controlling the on-off of the transistor. The invention realizes that the system frequency reduction points are kept consistent when high voltage or low voltage is input by calculating the average value of the output current and limiting the maximum output power of the system and controlling the working frequency of the system based on the average value.
Description
Technical Field
The invention relates to the field of electronics, in particular but not exclusively to a control circuit, a control method and a constant-voltage output switching power supply.
Background
As shown in fig. 1 to 3, in a conventional boost switching power supply control system with a constant on-time, amplitude-frequency (peak inductor current and switching frequency of a transistor) characteristics and overpower control are both controlled by an amplifier output signal, where overpower control is implemented by limiting a maximum on-time of the transistor, peak inductor current is implemented by controlling the on-time of the transistor, and when the on-time of the transistor is reduced to a certain proportion of a set maximum on-time, a working frequency of the system starts 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 maximum on-time tonmax of the transistor is set, the maximum output power of the system is as follows:
as can be seen from the above equation, when tonmax is constant, the larger the input voltage Vin is, the larger the maximum output power point is. If the down-conversion is started according to the fixed proportion of tonmax, the larger Vin is, the higher the power point (i.e. the maximum output power) corresponding to the down-conversion point is. Such as: when the input voltage is 90Vac, the corresponding over-power protection point is 10W, and 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 prior art scheme cannot achieve the same overpower protection point no matter the high voltage or low voltage is input, thereby affecting the system reliability.
In the prior art, the output power corresponding to the frequency reduction point increases with the increase of the input voltage, and if the frequency reduction points of high-voltage or low-voltage input are required to be consistent, a load compensation method is required. Since the maximum output power increases with the increase of the input voltage, it is usually actually required that the corresponding maximum output power is consistent for different input voltages, and therefore a complicated compensation method is required.
In view of the above, there is a need to design a new control method to overcome at least some of the above-mentioned disadvantages of the existing switching power supply.
Disclosure of Invention
The invention provides a control circuit, a control method and a constant-voltage output switching power supply, aiming at one or more problems in the prior art, and the invention realizes that the system frequency reduction points are kept consistent when high-voltage or low-voltage input is carried out by calculating the output current mean value of a switching power supply system, limiting the maximum output power of the system and controlling the working frequency of the system according to the output current mean value.
The technical solution for realizing the purpose of the invention is as follows:
according to an aspect of the present invention, a control circuit for a constant voltage output switching power supply including an inductor, a transistor, and a sampling resistor connected in series with the transistor, includes:
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 and obtained based on the voltage drop of the sampling resistor and the inductance current signal sampled by the sampling resistor;
the input end of the frequency control module is coupled with the output end of the output current mean value calculation module, and the frequency control module outputs a clock signal for controlling the switching period of the transistor and determines a frequency reduction point based on the output current mean value;
the first input end of the overpower control module is coupled with the output end of the output current average value calculation module, and the second input end of the overpower control module is connected with a reference signal and used for comparing the output current average value with a set reference signal and outputting an overpower 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 overpower 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 a clock signal and a drop frequency point of a transistor switching period and an overpower protection signal.
Optionally, the output current mean value calculating module includes a proportional operation circuit, and an input end of the proportional operation circuit is connected to the output current mean value and is configured to convert the calculated output current mean value into a voltage signal or a current signal in proportion and output the voltage signal or the current signal.
Optionally, the frequency drop 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 drop point is a time point when the operating frequency of the switching power supply starts to be reduced.
Optionally, the over-power control module includes a comparator, a first input end of the comparator is coupled to an output end of the output current average value calculating module, a second input end of the comparator is coupled to the reference signal, and an output end of the comparator is coupled to the control signal module, and is configured to compare the output current average value with the reference signal.
Optionally, the over-power control module outputs an over-power protection signal when the average value of the output current 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 be a set value.
Optionally, the control circuit includes:
the first input end of the constant voltage control module is connected with a reference voltage, and the second input end of the constant voltage control module is connected with the output feedback voltage of the switching power supply, and is used for comparing and amplifying the reference voltage and the output feedback voltage and outputting an error amplification signal;
and the amplitude control module is coupled with the output end of the constant voltage control module at a first input end, coupled with the connecting end of the transistor and the sampling resistor at a second input end, and coupled with the control signal module at an output end, 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 inductive current.
Optionally, the control circuit includes:
the first input end of the constant voltage control module is connected with a reference voltage, and the second input end of the constant voltage control module is connected with the output feedback voltage of the switching power supply, and is used for comparing and amplifying the reference voltage and the output feedback voltage and outputting an error amplification signal;
and 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 used for outputting a control signal for setting the conduction time of the transistor according to the error amplification signal.
Optionally, the constant voltage control module includes an error amplifier, a first input end of the error amplifier is connected to the reference voltage, and a second input end of the error amplifier is connected to the output feedback voltage of the switching power supply, so as to compare the reference voltage with the output feedback voltage, and obtain the error amplification signal.
Optionally, the amplitude control module includes a comparator, 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 the control signal module is configured 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 conduction time of the transistor.
According to another aspect of the present invention, a constant voltage output switching power supply includes an inductor, a transistor, a sampling resistor, and a control circuit of any one 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; the first input end of the control circuit is coupled with the connection 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.
According to still another aspect of the present invention, a control method for a constant voltage output switching power supply including an inductor, a transistor, and a sampling resistor connected in series with the transistor, includes:
acquiring voltage drop of a resistor and an inductive current signal sampled by the resistor, calculating an output current mean value of the switching power supply, and converting the output current mean value into a voltage signal or a current signal according to a set proportion;
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 reduction point;
comparing the voltage signal or the current signal with a reference signal to generate an over-power protection signal;
comparing the output feedback voltage of the switching power supply with a reference voltage to generate an error amplification signal; generating a control signal for controlling the peak value of the inductive current or a control signal for controlling the conduction time of the transistor according to the error amplification signal and the voltage drop of the sampling resistor;
and generating a control signal for controlling the on-off of the transistor according to a clock signal and a frequency reduction point of a switching period of the transistor, an over-power protection signal, and a control signal of an inductive current peak value or a control signal of the on-off time of the transistor.
Optionally, when the average value of the output currents corresponding to the voltage signals or the current signals reaches a set proportion of the maximum output current, a drop frequency point is set, and the working frequency of the switching power supply starts to be reduced.
Optionally, when the voltage signal or the current signal is greater than the reference signal, a control signal for controlling the transistor to turn off is output, or a control signal for limiting the output current to a set value is output.
Compared with the prior art, the invention adopting the technical scheme has the following technical effects:
the control circuit obtains the average value of the output current of the switching power supply through indirect calculation, limits the maximum output power of the system according to the average value of the output current, realizes the consistency of the corresponding maximum output power points 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, the system drop frequency points are 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 invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:
fig. 1 shows a schematic diagram of a boost switching power supply system in the prior art.
Fig. 2 shows a graph of operating frequency versus output power for a prior art boost-type switching power supply system.
Fig. 3 shows a graph of an over-power protection point versus an input voltage for a prior art boost switching power supply system.
Fig. 4 is a schematic diagram showing the structure of the constant voltage output switching power supply and the control circuit thereof according to the present invention.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
The description in this section is for several exemplary embodiments only, and the present invention is not limited only to the scope of the embodiments described. Combinations of different embodiments, and substitutions of features from different embodiments, or similar prior art means may be substituted for or substituted for features of the embodiments shown and described.
The term "coupled" or "connected" in this specification includes both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as a conductor, wherein the electrically conductive medium may contain parasitic inductance or parasitic capacitance, or through an intermediate circuit or component as described in the embodiments in the specification; indirect connections may also include connections through other active or passive devices that perform the same or similar function, such as connections through switches, signal amplification circuits, follower circuits, and so on. "plurality" or "plurality" means two or more.
According to one aspect of the present invention, 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 with the transistor Q1 in series. In the constant-voltage output switching power supply system, the output power Po = Vout Iout, the output power and the output current are in a direct proportion relation, and the magnitude of the output current can directly represent the magnitude of the output power.
According to one embodiment of the present invention, the control circuit includes an output current mean value calculation module, a frequency control module, an over-power control module, and a control signal module, wherein:
and the input end of the output current average value calculation module is coupled to the connection 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 inductive current signal thereof. And obtaining the charging and discharging time of the inductor according to the inductor current signal. Preferably, the output current average value calculating module includes a proportional operation circuit, and an input end of the proportional operation circuit is connected to the output current average value, and is configured to convert the calculated output current average value into a voltage signal or a current signal in proportion and output 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 voltage-reducing circuit is coupled with the output end of the output current mean value calculation module, and the voltage-reducing circuit outputs a clock signal for controlling the switching period of the transistor Q1 and determines a voltage-reducing point based on the output current mean value. That is, the frequency control module is controlled by the output current mean value. 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 drop point is when the average value of the output current reaches a predetermined proportion of the maximum output current. The output voltage is multiplied by the average value of the output current = the output power, in the constant-voltage output switch power supply system, the output voltage is unchanged, the average value of the output current can directly reflect the output power, and the drop frequency point is set according to the average value of the output current, which is equivalent to the drop frequency point set according to the output power. The average value of the output current starts to reduce the frequency when reaching a certain proportion of the maximum output current, which is equivalent to starting to reduce the frequency 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 of the over-power protection circuit is coupled with the output end of the output current mean value calculation module, and the second input end of the over-power protection circuit is connected with the reference signal and used for comparing the output current mean value with the set reference signal and outputting an over-power protection signal according to the comparison result. In one embodiment, the over-power control module outputs an over-power protection signal when the average value of the output current is greater than the reference signal. Preferably, the overpower control module includes a comparator, a first input end of the comparator is coupled to an output end of the output current average value calculating module, a second input end of the comparator is coupled to the reference signal, and an output end of the comparator is coupled to the control signal module, and is configured to compare the output current average value with the reference signal and output an overpower protection signal according to a comparison result. Still preferably, the over-power control module includes a comparator, an input end of the comparator is coupled to an output end of the output current average value calculating module, and when the output current average value is greater than a comparator turning threshold, 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.
And the input end of the control signal module is coupled with the output ends of the frequency control module and the overpower 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 drop frequency point of a switching period of the transistor Q1 and an overpower protection signal.
According to another embodiment of the present invention, as shown in fig. 4, the control circuit includes an output current mean value calculation module, a frequency control module, an overpower control module, a constant voltage control module, an amplitude control module, and a control signal module. Wherein:
and the input end of the output current average value calculation module is coupled to the connection 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 inductive current signal thereof. Preferably, the output current mean value calculation module includes a proportional operation circuit, and an input end of the proportional operation circuit is connected to the output current mean value and is used for converting the calculated output current mean 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 calculation module is coupled with the output end of the output current average value calculation module, and outputs a clock signal for controlling the switching period of the transistor Q1 based on the output current average value and determines a frequency reduction point, wherein the frequency reduction point is a time point for starting to reduce the working frequency of the switching power supply. In one embodiment, the frequency drop point is when the average value of the output current reaches a predetermined 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 of the over-power protection circuit is coupled with the output end of the output current mean value calculation module, and the second input end of the over-power protection circuit is connected with the reference signal and used for comparing the output current mean value with the set reference signal and outputting an over-power protection signal according to the comparison result. In one embodiment, the over-power control module outputs an over-power protection signal when the average value of the output current is greater than a reference signal. Preferably, the overpower control module includes a comparator, a first input end of the comparator is coupled to an output end of the output current average value calculating module, a second input end of the comparator is coupled to the reference signal, and an output end of the comparator is coupled to the control signal module, and is configured to compare the output current average value with the reference signal and output an overpower 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 a first input end of the constant voltage control module is connected with a reference voltage, and a second input end of the constant voltage control module is connected with an output voltage feedback signal of the switching power supply, and is used for comparing and amplifying the reference voltage and the output feedback signal and outputting an error amplification signal. Preferably, the constant voltage control module includes an error amplifier, a first input end of the error amplifier is connected to the reference voltage, and a second input end of the error amplifier is connected to the output voltage feedback signal of the switching power supply, and the error amplifier is configured to compare the reference voltage with the output feedback signal to obtain an 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, a first input terminal of the constant voltage control module is coupled to an output terminal of the constant voltage control module, a second input terminal of the constant voltage control module is coupled to a connection terminal of the transistor Q1 and the sampling resistor Rcs, and an output terminal of the constant voltage control module is coupled to the control signal module, and is configured to compare the error amplification signal with a voltage drop Vcs of the sampling resistor Rcs and output a control signal for limiting a peak value of the inductor current. Preferably, the amplitude control module includes a comparator, 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 the comparator 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 a conduction 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.
And the input end of the control signal module is coupled with the output ends of the frequency control module, the overpower 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 a control signal for controlling the on-off of the transistor Q1 is output based on a clock signal of a switching period of the transistor Q1, a frequency reduction point, an overpower protection signal and a control signal of an inductive current peak value or a control signal for controlling the on-off time of the transistor Q1.
According to another aspect of the present invention, a constant voltage output switching power supply, as shown in fig. 4, includes an inductor, a transistor Q1, a sampling resistor Rcs, and the above control circuit. 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 with the connection end of the transistor Q1 and the sampling resistor Rcs, the second input end of the control circuit is connected with the output voltage feedback signal, and the output end of the control circuit is coupled with the control end of the transistor Q1.
According to still another aspect of the present invention, a control method for a constant voltage output switching power supply including an inductor, a transistor, and a sampling resistor connected in series with the transistor, includes:
s1, obtaining voltage drop of a resistor and an inductive current signal sampled by the resistor, calculating an output current mean value of the switching power supply, and converting the output current mean value into a voltage signal or a current signal according to a set proportion.
And 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 reduction point. Preferably, the set 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.
And 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 output, or a control signal for limiting the output current to a set value is output.
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 conduction time of the transistor according to the error amplification signal and the voltage drop of the sampling resistor.
And S5, generating a control signal for controlling the on-off of the transistor according to the clock signal and the frequency reduction point of the transistor switching period, the over-power protection signal, and the control signal of the inductive current peak value or the control signal of the transistor on-time.
The control circuit, the control method and the constant-voltage output switching power supply provided by the invention realize that the system frequency reduction points are kept consistent when high voltage or low voltage is input by calculating the output current mean value of the switching power supply system, limiting the maximum output power of the system according to the output current mean value and controlling the working frequency of the system.
Those skilled in the art should understand that the logic controls such as "high" and "low", "set" and "reset", "and gate" and "or gate", "non-inverting input" and "inverting input" in the logic controls referred to in the specification or the drawings may be exchanged or changed, and the subsequent logic controls may be adjusted to achieve the same functions or purposes as the above-mentioned embodiments.
The description and applications of the invention herein are illustrative and are not intended to limit the scope of the invention to the embodiments described above. The descriptions related to the effects or advantages in the specification may not be reflected in practical experimental examples due to uncertainty of specific condition parameters or influence of other factors, and the descriptions related to the effects or advantages are not used for limiting the scope of the invention. Variations and modifications of the embodiments disclosed herein are possible, and alternative and equivalent various components of the embodiments will be apparent to those skilled in the art. It will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, and with other components, materials, and parts, 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 invention.
Claims (15)
1. A control circuit for a constant voltage output switching power supply including an inductor, 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 and obtained based on the voltage drop of the sampling resistor and the inductance current signal sampled by the sampling resistor;
the input end of the frequency control module is coupled with the output end of the output current mean value calculation module, and the frequency control module outputs a clock signal for controlling the switching period of the transistor and determines a frequency reduction point based on the output current mean value;
the first input end of the overpower control module is coupled with the output end of the output current mean value calculation module, and the second input end of the overpower control module is connected with a reference signal and used for comparing the output current mean value with a set reference signal and outputting an overpower 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 overpower control module, the output end of the control signal module is coupled with the control end of the transistor, and a clock signal and a drop frequency point based on the switching period of the transistor and an overpower protection signal output control signal for controlling the on-off of the transistor.
2. The control circuit of claim 1, wherein the output current mean value calculation module comprises a proportional operation circuit, and an input end of the proportional operation circuit is connected to the output current mean value and is configured to convert the calculated output current mean value into a voltage signal or a current signal in proportion and output the voltage signal or the current signal.
3. The control circuit of claim 1, wherein the down-conversion point in the frequency control module is when the average value of the output current reaches a predetermined proportion of the maximum output current.
4. The control circuit according to claim 1 or 3, wherein the down-conversion frequency point is a time point when the operating 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, a first input terminal of the comparator is coupled to the output terminal of the output current average value calculation module, a second input terminal of the comparator is coupled to the reference signal, and an output terminal of the comparator is coupled to the control signal module for comparing the output current average value with 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 average value of the output current is greater than the reference signal.
7. The control circuit of claim 1 or 6, wherein the over-power protection signal comprises a control signal for controlling a transistor to be turned off or a control signal for limiting an 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 a 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;
and the amplitude control module is coupled with the output end of the constant voltage control module at a first input end, coupled with the connecting end of the transistor and the sampling resistor at a second input end, and coupled with the control signal module at an output end, 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 a reference voltage, and the second input end of the constant voltage control module is connected with the output feedback voltage of the switching power supply, and is used for comparing and amplifying the reference voltage and the output feedback voltage and outputting an error amplification signal;
and 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 used for outputting a control signal for setting the conduction 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 is connected to a reference voltage, and a second input terminal of the error amplifier is connected to an output feedback voltage of the switching power supply, for comparing the reference voltage with the output feedback voltage to obtain an error amplified signal.
11. The control circuit of claim 8, wherein the amplitude control module comprises a comparator, a first input terminal of the comparator is coupled to an output terminal of the constant voltage control module, a second input terminal of the comparator is coupled to a connection terminal of the transistor and the sampling resistor, and an output terminal of the comparator is coupled to the control signal module, and is configured 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 conduction time of the transistor.
12. A constant voltage output switching power supply comprising an inductor, a transistor, a sampling resistor, and the control circuit of 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 connection 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.
13. A control method for a constant-voltage output switching power supply including an inductor, a transistor, and a sampling resistor connected in series with the transistor, comprising:
acquiring voltage drop of a resistor and an inductive current signal sampled by the resistor, calculating an output current mean value of the switching power supply, and converting the output current mean value into a voltage signal or a current signal according to a set proportion;
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 reduction point;
comparing the voltage signal or the current signal with a reference signal to generate an over-power protection signal;
comparing the output feedback voltage of the switching power supply with a reference voltage to generate an error amplification signal; generating a control signal for controlling the peak value of the inductive current or a control signal for controlling the conduction time of the transistor according to the error amplification signal and the voltage drop of the sampling resistor;
and generating a control signal for controlling the on-off of the transistor according to a clock signal and a frequency reduction point of a switching period of the transistor, an over-power protection signal, and a control signal of an inductive current peak value or a control signal of the on-off time of the transistor.
14. The control method according to claim 13, wherein a down-frequency point is set when the average value of the output current corresponding to the voltage signal or the current signal reaches a set proportion of the maximum output current, and the operating frequency of the switching power supply starts to be reduced.
15. The control method according to claim 13, wherein when the voltage signal or the current signal is greater than the reference signal, a control signal for turning off the transistor is outputted, or a control signal for limiting the output current to a set value is outputted.
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| CN202211378078.8A CN115664163A (en) | 2022-11-04 | 2022-11-04 | Control circuit, control method and constant-voltage output switching power supply |
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| CN202211378078.8A CN115664163A (en) | 2022-11-04 | 2022-11-04 | Control circuit, control method and constant-voltage output switching power supply |
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| CN115664163A true CN115664163A (en) | 2023-01-31 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115932380A (en) * | 2023-02-23 | 2023-04-07 | 杰华特微电子股份有限公司 | Power detection circuit and detection method of switching circuit and switching circuit |
| CN117375388A (en) * | 2023-09-26 | 2024-01-09 | 山东艾诺智能仪器有限公司 | Self-adaptive over-power protection circuit |
-
2022
- 2022-11-04 CN CN202211378078.8A patent/CN115664163A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115932380A (en) * | 2023-02-23 | 2023-04-07 | 杰华特微电子股份有限公司 | Power detection circuit and detection method of switching circuit and switching circuit |
| CN117375388A (en) * | 2023-09-26 | 2024-01-09 | 山东艾诺智能仪器有限公司 | Self-adaptive over-power protection circuit |
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