CN115864836B - Switching power supply control circuit and electronic equipment - Google Patents
Switching power supply control circuit and electronic equipment Download PDFInfo
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- CN115864836B CN115864836B CN202310050195.XA CN202310050195A CN115864836B CN 115864836 B CN115864836 B CN 115864836B CN 202310050195 A CN202310050195 A CN 202310050195A CN 115864836 B CN115864836 B CN 115864836B
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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
Abstract
The invention discloses a switching power supply control circuit and electronic equipment, and belongs to the technical field of electronics. The switching power supply control circuit includes: a first pulse circuit configured to provide a first pulse signal; the timing circuit is configured to send a timing signal to the first pulse circuit when the first period duration of the first pulse signal reaches the target period duration, so that the first pulse circuit inverts the level of the first pulse signal according to the timing signal; and a second pulse circuit configured to determine a second period duration based on the first period duration of the first pulse signal to generate a second pulse signal having the second period duration, the second pulse signal being used to drive the switching power supply. According to the invention, the switching frequency of the switching power supply is controlled, so that the intermittent working frequency of the inductive current is limited above the target frequency, and is not in the sound frequency range which can be heard by human ears, and the user experience is improved.
Description
Technical Field
The invention belongs to the technical field of electronics, and particularly relates to a switching power supply control circuit and electronic equipment.
Background
In general, when the switching power supply is operated in a light load mode, the switching power supply system intermittently adjusts the inductor current according to the load size. Normally, the frequency range of sound that the human ear can hear is between 20Hz and 20KHz, so when the intermittent working frequency of the inductive current is between 20Hz and 20KHz, the human ear can hear the howling of the inductor in the switching power supply circuit. This phenomenon occurs in many electronic products, and it makes the system that would otherwise operate silently appear slightly loud, severely affecting the user's use.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention provides the switching power supply control circuit and the electronic equipment, wherein the intermittent working frequency of the inductive current is not in the sound frequency range which can be heard by human ears, so that the user experience is improved.
In a first aspect, the present invention provides a switching power supply control circuit comprising: a first pulse circuit configured to provide a first pulse signal; the timing circuit is electrically connected with the first pulse circuit and is configured to send a timing signal to the first pulse circuit when the first period duration of the first pulse signal reaches the target period duration, so that the first pulse circuit inverts the level of the first pulse signal according to the timing signal; and the second pulse circuit is respectively and electrically connected with the first pulse circuit and the switching power supply and is configured to determine a second period duration based on the first period duration of the first pulse signal so as to generate a second pulse signal with the second period duration, wherein the second pulse signal is used for driving the switching power supply.
According to the switching power supply control circuit, the timing circuit is arranged to detect and control the first period duration of the first pulse signal output by the first pulse circuit, so that the overlong first period duration is avoided, the second period duration of the second pulse signal is controlled, the switching frequency of the switching power supply is controlled, the intermittent working frequency of the inductive current is limited above the target frequency, the intermittent working frequency of the inductive current is not in the audible frequency range of human ears, and the user experience is improved.
According to one embodiment of the present invention, the switching power supply control circuit further includes: the first amplifying circuit is electrically connected with the switching power supply and is configured to compare the feedback output voltage of the switching power supply with a first reference voltage and generate a first amplifying voltage based on a comparison result; the first pulse circuit is electrically connected with the first amplifying circuit and is further configured to compare the first amplifying voltage with the second reference voltage and provide a first pulse signal based on the comparison result.
According to one embodiment of the present invention, a first pulse circuit includes: a voltage circuit having a first voltage output configured to provide a first voltage and a second voltage output configured to provide a second voltage, the first voltage and the second voltage having different voltage values; the first input end of the first switch is electrically connected with the first voltage output end, and the second input end of the first switch is electrically connected with the second voltage output end; the positive input end of the comparator is electrically connected with the output end of the first switch so as to be connected with the second reference voltage, the negative input end of the comparator is electrically connected with the first amplifying circuit so as to be connected with the first amplifying voltage, and the output end of the comparator outputs a first pulse signal; and the timing circuit is electrically connected with the control end of the first switch and is configured to control the output end of the first switch to be communicated with the first input end or the second input end.
According to one embodiment of the invention, the voltage circuit further has a third voltage output configured to provide a third voltage and a fourth voltage output configured to provide a fourth voltage, the third voltage and the fourth voltage having different voltage values; the first pulse circuit further includes: the first input end of the second switch is electrically connected with the third voltage output end, and the second input end of the second switch is electrically connected with the fourth voltage output end; the input end of the clamping circuit is electrically connected with the output end of the second switch, and the output end of the clamping circuit is electrically connected with the first amplifying circuit so as to clamp the first amplifying voltage; the timing circuit is also electrically connected with the control end of the second switch and is also configured to control the output end of the second switch to be communicated with the first input end or the second input end.
According to one embodiment of the invention, the first voltage is greater than the third voltage, the third voltage is greater than the second voltage, and the second voltage is greater than the fourth voltage; and the timing circuit is configured to control the first switch to switch from the first voltage to the second voltage when the first period duration of the first pulse signal reaches the target period duration, and control the second switch to switch from the third voltage to the fourth voltage.
According to one embodiment of the invention, a timing circuit is electrically connected to the output of the comparator, the timing circuit being configured to start timing when a falling edge of the first pulse signal is detected.
According to one embodiment of the present invention, the switching power supply control circuit further includes: the second amplifying circuit is electrically connected with the first amplifying circuit and is configured to compare the first amplifying voltage with a third reference voltage, and generate a second amplifying voltage based on the comparison result, wherein the third reference voltage represents the output current value of the switching power supply; the second pulse circuit is also electrically connected with the second amplifying circuit and is further configured to determine a duty cycle based on the second amplifying voltage and a second period duration based on the first period duration to generate a second pulse signal with the duty cycle and the second period duration.
According to one embodiment of the invention, the first amplifying circuit comprises a first error amplifier, wherein a non-inverting input end of the first error amplifier is connected with a first reference voltage, an inverting input end of the first error amplifier is connected with a feedback output voltage, and an output end of the first error amplifier outputs the first amplifying voltage; the second amplifying circuit comprises a second error amplifier, wherein the non-inverting input end of the second error amplifier is connected with the first amplifying voltage, the inverting input end of the second error amplifier is connected with the third reference voltage, and the output end of the second error amplifier outputs the second amplifying voltage.
According to one embodiment of the invention, the first period duration is equal to the second period duration and the target period duration is less than or equal to 40 μs.
In a second aspect, the present invention provides an electronic device comprising a switching power supply and a switching power supply control circuit according to any one of the preceding embodiments, the switching power supply control circuit being electrically connected to the switching power supply.
According to the electronic equipment, under the control of the switching power supply control circuit, the intermittent working frequency of the inductive current is limited above the target frequency and is not in the sound frequency range which can be heard by human ears, so that the user experience is improved.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
fig. 1 is a schematic diagram of a switching power supply control circuit according to an embodiment of the present invention;
FIG. 2 is a schematic waveform diagram of an inductor current according to an embodiment of the present invention;
FIG. 3 is a second schematic diagram of a switching power supply control circuit according to an embodiment of the present invention;
FIG. 4 is a third schematic diagram of a switching power supply control circuit according to an embodiment of the present invention;
fig. 5 is a schematic diagram of voltage variation of a switching power supply control circuit according to an embodiment of the present invention.
Reference numerals:
a first pulse circuit 100, a voltage circuit 110, a first voltage output terminal 111, a second voltage output terminal 112, a third voltage output terminal 113, a fourth voltage output terminal 114, a first switch 120, a second switch 130, and a clamp circuit 140;
a second pulse circuit 200;
a timer circuit 300;
a switching power supply 400;
a first amplifying circuit 500;
a second amplifying circuit 600;
comparator COMP, first error amplifier EA1, second error amplifier EA2.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
Referring to fig. 1, one embodiment of the present invention provides a switching power supply control circuit.
In the present embodiment, the switching power supply control circuit includes a first pulse circuit 100, a second pulse circuit 200, and a timer circuit 300; the first pulse circuit 100 is configured to provide a first pulse signal; the timing circuit 300 is electrically connected to the first pulse circuit 100, and the timing circuit 300 is configured to send a timing signal to the first pulse circuit 100 when the first period duration of the first pulse signal reaches the target period duration, so that the first pulse circuit 100 inverts the level of the first pulse signal according to the timing signal; the second pulse circuit 200 is electrically connected to the first pulse circuit 100 and the switching power supply 400, respectively, and the second pulse circuit 200 is configured to determine a second period duration based on the first period duration of the first pulse signal to generate a second pulse signal having the second period duration, the second pulse signal being used to drive the switching power supply 400.
It is understood that the switching power supply 400 is internally integrated with a power switch tube, such as a MOS (Metal-Oxide-Semiconductor) tube. The second pulse circuit 200 may be electrically connected to the gate of the MOS transistor to apply the second pulse signal to the MOS transistor. The second pulse signal may include a high level portion and a low level portion, wherein the gate of the MOS transistor is turned on when a high level is applied and turned off when a low level is applied; of course, the gate of the MOS transistor is turned off when a high level is applied and turned on when a low level is applied. The specific structure and principle of the switching power supply 400 are well known and will not be described in detail here.
Referring to fig. 2, il denotes an inductor current, and Vout denotes an output voltage of the switching power supply 400. The switching power supply 400 is typically operated in an intermittent mode when operating in a light load mode. The power switch tube is turned on and then turned off in one period, the inductance current rises in the turn-on period of the power switch tube, continuously drops to zero in the turn-off period, and is maintained. The output voltage of the switching power supply 400 increases when the inductor current is greater than zero, and decreases when the inductor current is kept zero. One duty cycle of the inductor current may rise from zero to the next from zero, which corresponds to the actual time period of the power switching tube between the closing instant and the next closing instant.
In some embodiments, the second pulse circuit 200 may integrate a pulse width modulation function and a pulse frequency modulation function. The second pulse circuit 200 may generate a pulse modulation signal having a variable duty ratio and a variable frequency, which is the second pulse signal. The first pulse signal can be used as a control signal of a pulse frequency modulation function to control the frequency of the second pulse signal.
In some embodiments of the invention, the first period duration may be equal to the second period duration, e.g., both the first period duration and the second period duration are 40 μs. The second pulse circuit 200 can directly modulate the second pulse signal by using the first pulse signal as a clock signal, thereby facilitating signal processing. Meanwhile, since the first period duration may be equal to the second period duration, after the target period duration is set, the maximum period duration of the second pulse signal is the target period duration.
In some embodiments of the invention, the target period duration may be less than or equal to 40 μs. Taking the target period duration of 40 mu s as an example, the working frequency corresponding to 40 mu s is 25kHz, and the maximum value of the second period duration of the second pulse signal is 40 mu s; thus, the switching frequency of the switching power supply 400 is 25kHz, and the corresponding operating frequency of the inductor current is 25kHz. And, as the first period duration of the first pulse signal is shorter, the operating frequency of the inductor current is higher.
In some embodiments, the timing circuit 300 may include a timer. The timer may detect the first pulse signal and count the time with the rising edge (or the falling edge) of the first pulse signal as the count start time. If the counted time reaches the target period duration, if the counted time reaches 40 mu s, the timer sends a counted signal to the first pulse circuit 100; if the timer detects a rising edge (or a falling edge) again when the counted time does not reach the target period duration, the timer counts again.
In the present embodiment, when the first pulse circuit 100 receives the timing signal, the output first pulse signal is controlled to be inverted, and the first pulse signal is then subjected to the next cycle. That is, when the timing signal is received, the first pulse signal is outputted at a high level, and the first pulse circuit 100 is switched to output at a low level; when the timing signal is received, the first pulse signal is outputted at a low level, and the first pulse circuit 100 switches to output a high level.
In some embodiments, the signal generator in the first pulse circuit 100 may directly invert the output when the timing signal is detected; alternatively, an inverter or the like may be provided in the first pulse circuit 100, and the timing signal is switched in or out of the loop by controlling the inverter to invert the level of the first pulse signal.
It will be appreciated that as the level of the first pulse signal is inverted, the second pulse signal is also inverted accordingly. Because the inversion time is usually in the period that the power switch tube is in turn-off, the level after inversion can control the power switch tube to be turned on according to the control logic, the inductance current starts to rise, and the inductance current enters a new working period.
According to the switching power supply control circuit, the timing circuit 300 is arranged to detect and control the first period duration of the first pulse signal output by the first pulse circuit 100, so that the overlong first period duration is avoided, the second period duration of the second pulse signal is controlled, the switching frequency of the switching power supply 400 is further controlled, the intermittent working frequency of the inductive current is limited above the target frequency, the intermittent working frequency is not in the audible frequency range of human ears, and the user experience is improved.
Referring to fig. 3, in some embodiments of the present invention, the switching power supply control circuit may further include a first amplifying circuit 500; the first amplifying circuit 500 is electrically connected to the switching power supply 400, and the first amplifying circuit 500 is configured to compare a feedback output voltage of the switching power supply 400 with a first reference voltage and generate a first amplified voltage based on the comparison result; the first pulse circuit 100 is electrically connected to the first amplifying circuit 500, and the first pulse circuit 100 is further configured to compare the first amplified voltage with the second reference voltage and provide a first pulse signal based on the comparison result.
It should be noted that the feedback output voltage may represent the output voltage of the switching power supply 400. The switching power supply control circuit may further include a voltage sampling circuit configured to sample an output voltage of the switching power supply 400 and convert the sampled output voltage into a feedback signal, and transmit the feedback signal to the first amplifying circuit 500. The first amplifying circuit 500 uses the voltage of the feedback signal as a feedback output voltage. The sampling circuit can be composed of a voltage division loop formed by connecting a plurality of resistors in series.
The first reference voltage may represent a desired output voltage of the switching power supply 400, and a difference between the feedback output voltage and the first reference voltage may reflect a difference between an actual output and the desired output of the switching power supply 400, which may also indirectly reflect a magnitude of a load current of the switching power supply 400.
In some embodiments, the first amplifying circuit 500 may perform a difference between the feedback output voltage and the first reference voltage to perform a comparison; the first amplified voltage is obtained by amplifying the difference. Wherein, amplifying the difference value can facilitate subsequent detection and identification.
In some embodiments, the first pulse circuit 100 may determine a magnitude between the first amplified voltage and the second reference voltage; outputting a high level when the first amplified voltage is greater than or equal to the second reference voltage, and outputting a low level when the first amplified voltage is less than the second reference voltage; or outputting a low level when the first amplified voltage is greater than or equal to the second reference voltage, and outputting a high level when the first amplified voltage is less than the second reference voltage. The second reference voltage may be used to set the duty cycle of the first pulse signal, and its specific value may be set according to the control requirement of the switching power supply 400, which is not limited in this embodiment.
According to the switching power supply control circuit, the first pulse signal is generated according to the feedback output voltage of the switching power supply 400, so that closed-loop control is formed, and the control precision is improved while the inductor howling of the switching power supply 400 is reduced.
Referring to fig. 4, in some embodiments of the present invention, the first pulse circuit 100 may include a voltage circuit 110, a first switch 120, and a comparator COMP; the voltage circuit 110 has a first voltage output terminal 111 configured to supply a first voltage and a second voltage output terminal 112 configured to supply a second voltage, the first voltage and the second voltage having different voltage values; a first input terminal of the first switch 120 is electrically connected to the first voltage output terminal 111, and a second input terminal of the first switch 120 is electrically connected to the second voltage output terminal 112; the non-inverting input terminal of the comparator COMP is electrically connected to the output terminal of the first switch 120 to access the second reference voltage, the inverting input terminal of the comparator COMP is electrically connected to the first amplifying circuit 500 to access the first amplifying voltage, and the output terminal of the comparator COMP outputs the first pulse signal; the timing circuit 300 is electrically connected to the control terminal of the first switch 120, and the timing circuit 300 is configured to control the output terminal of the first switch 120 to communicate with the first input terminal or the second input terminal.
It should be noted that the voltage circuit 110 may have a plurality of voltage output terminals, and each voltage output terminal has a different voltage value. The voltage circuit 110 may convert an input power source into a plurality of different voltages, which may be divided or composed of elements of a power management chip.
In some embodiments, the first switch 120 may have a first conductive state and a second conductive state. In the first conducting state, the output terminal of the first switch 120 is communicated with the first input terminal; in the second conductive state, the output terminal of the first switch 120 is in communication with the second input terminal. In general, the first switch 120 mainly operates in a first conductive state or a second conductive state, and the timing circuit 300 may generate a control signal to the control terminal of the first switch 120 to control the first switch 120 to switch between the first conductive state or the second conductive state.
It is understood that the second reference voltage is equal to the first voltage when the first switch 120 is in the first conductive state, and the second reference voltage is equal to the second voltage when the first switch 120 is in the second conductive state. Therefore, the second reference voltage is changed when the first switch 120 is switched.
In the present embodiment, when the second reference voltage is greater than or equal to the first amplified voltage, the output terminal of the comparator COMP is at a high level, and when the second reference voltage is less than the first amplified voltage, the output terminal of the comparator COMP is at a low level. Therefore, by setting the voltages of the first voltage and the second voltage, the level of the output terminal of the comparator COMP can be inverted when the first switch 120 is switched.
In some embodiments of the present invention, the voltage circuit 110 may further have a third voltage output terminal 113 and a fourth voltage output terminal 114, the third voltage output terminal 113 being configured to provide a third voltage, the fourth voltage output terminal 114 being configured to provide a fourth voltage, the third voltage and the fourth voltage having different voltage values; the first pulse circuit 100 may further include a second switch 130 and a clamp circuit 140; the first input terminal of the second switch 130 is electrically connected to the third voltage output terminal 113, and the second input terminal of the second switch 130 is electrically connected to the fourth voltage output terminal 114; an input end of the clamping circuit 140 is electrically connected with an output end of the second switch 130, and an output end of the clamping circuit 140 is electrically connected with the first amplifying circuit 500 to clamp the first amplifying voltage; the timing circuit 300 is further electrically connected to the control terminal of the second switch 130, and the timing circuit 300 is further configured to control the output terminal of the second switch 130 to communicate with the first input terminal or the second input terminal.
In some embodiments, the second switch 130 may have a first conductive state and a second conductive state. In the first conducting state, the output end of the second switch 130 is communicated with the first input end; in the second conducting state, the output terminal of the second switch 130 is in communication with the second input terminal. In general, the second switch 130 mainly operates in a first conductive state or a second conductive state, and the timing circuit 300 may generate a control signal to a control terminal of the first switch to control the second switch 130 to switch between the first conductive state or the second conductive state.
It is understood that the input voltage of the clamp circuit 140 is equal to the first voltage when the second switch 130 is in the first conductive state, and the input voltage of the clamp circuit 140 is equal to the second voltage when the second switch 130 is in the second conductive state. Therefore, when the second switch 130 is switched, the input voltage of the clamp circuit 140 changes.
It should be noted that the timing circuit 300 may output a first timing signal VA1 and a second timing signal VA2, where the first timing signal VA1 is used to control the first switch 120 to switch, and the second timing signal VA2 is used to control the second switch 130 to switch. The first timing signal VA1 and the second timing signal VA2 may be at a high level or a low level, where the high level corresponds to the first conductive state and the low level corresponds to the second conductive state; of course, the reverse is also possible.
In some embodiments, the clamping circuit 140 may clamp the first amplified voltage in accordance with the input voltage. The clamping of the first amplified voltage may refer to clamping a minimum value of the first amplified voltage to the input voltage or clamping a maximum value of the first amplified voltage to the input voltage.
For a clearer explanation of the working principle of the switching power supply control circuit of the present invention, the following examples are presented:
referring to fig. 5, vc1 represents a first amplified voltage, V1 represents a first voltage, V2 represents a second voltage, V3 represents a third voltage, V4 represents a fourth voltage, and PFM represents an output waveform of the comparator COMP. In one example of the present invention, the first amplifying circuit 500 adopts a negative feedback form, when the output voltage of the switching power supply 400 becomes larger, VC1 decreases and the switching power supply control circuit controls the switching power supply 400 to decrease the output voltage when the feedback output voltage is greater than the first reference voltage; when the output voltage of the switching power supply 400 becomes smaller, and the feedback output voltage is smaller than the first reference voltage, VC1 increases, and the switching power supply control circuit controls the switching power supply 400 to increase the output voltage.
In this example, the timing circuit 300 is electrically connected to the output of the comparator COMP, the timing circuit 300 being configured to start timing when a falling edge of the first pulse signal is detected. The falling edge of the first pulse signal is used as the start of a control period, and the second pulse circuit 200 switches the power switch tube in the switch power supply 400 from the non-switching state to the switching state at the falling edge time of the first pulse signal, so that the switch power supply 400 enters a new switching period.
In this example, the first voltage V1 is greater than the third voltage V3, the third voltage V3 is greater than the second voltage V2, and the second voltage V2 is greater than the fourth voltage V4. The timing circuit 300 is configured to control the first switch 120 to switch from switching to the second voltage from switching to the third voltage and control the second switch 130 to switch to the fourth voltage when the first period duration of the first pulse signal reaches the target period duration. The working process of the switching power supply control circuit is divided into two cases.
First case (section t1 in fig. 5): in the light load mode of the switching power supply 400, the timing circuit 300 starts with the falling edge of the PFM signal as timing, and at the beginning, the first amplified voltage VC1 is greater than the first voltage V1, and the comparator COMP outputs a low level. During the timing time, the first switch 120 and the second switch 130 are both switched to the first on state, at this time, the second reference voltage is equal to the first voltage V1, and the clamp circuit 140 clamps the first amplified voltage with the third voltage V3, so that the first amplified voltage VC1 is not less than the third voltage V3. When the first amplified voltage VC1 falls below the first voltage V1, the comparator COMP outputs a high level. The first amplified voltage VC1 is then controlled at the third voltage V3 by the clamp circuit 140. At the end of the timing time (entering t 2), the timing circuit 300 switches both the first switch 120 and the second switch 130 to the second conducting state, at this time, since the first amplified voltage VC1 is greater than the second voltage V2, the comparator COMP output becomes low level, and enters the next cycle, and the cycle time of the current cycle is controlled to be the timing duration. Meanwhile, when the comparator COMP output changes from the high level to the low level, the timing circuit 300 restarts timing.
Second case (section t3 in fig. 5): the clamping voltage of the clamping circuit 140 becomes the fourth voltage V4, the first amplified voltage VC1 continues to decrease, and when the first amplified voltage VC1 is smaller than the second voltage, the comparator COMP outputs a high level, and the timing circuit 300 switches both the first switch 120 and the second switch 130 to the first conductive state. Since the output voltage becomes low, the first amplified voltage VC1 starts to rise, which may exceed the first voltage V1 before the timing of the timing circuit 300 is finished, the comparator COMP output becomes low, and the next cycle is entered, and the cycle time of the current cycle is smaller than the timing duration. Meanwhile, when the comparator COMP output changes from the high level to the low level, the timing circuit 300 restarts timing.
With continued reference to fig. 3, in some embodiments of the invention, the switching power supply control circuit may further include a second amplification circuit 600; the second amplifying circuit 600 is electrically connected to the first amplifying circuit 500, and the second amplifying circuit 600 is configured to compare the first amplifying voltage with a third reference voltage, and generate a second amplifying voltage based on the comparison result, the third reference voltage representing an output current value of the switching power supply 400; the second pulse circuit 200 is also electrically connected to the second amplifying circuit 600, the second pulse circuit 200 being further configured to determine a duty cycle based on the second amplified voltage, and to determine a second period duration based on the first period duration, to generate a second pulse signal having the duty cycle and the second period duration.
In some embodiments, the switching power supply control circuit may further include a current sampling circuit configured to sample an output current of the switching power supply 400 and convert the sampled output current into a feedback signal, and transmit the feedback signal to the second amplifying circuit 600. The second amplifying circuit 600 uses the voltage of the feedback signal as a third reference voltage.
In some embodiments, the second amplifying circuit 600 may perform a difference between the first amplifying voltage and the third reference voltage to perform a comparison; and amplifying the difference value to obtain a second amplified voltage. Wherein, amplifying the difference value can facilitate subsequent detection and identification.
In this embodiment, the voltage loop and the current loop are used to form a dual-loop control, the voltage loop is used as an outer loop to transmit the output to the current loop, the current loop is used as an inner loop to form the output according to the input of the voltage loop and the sampling current, and the output is used to control the second pulse circuit 200 to generate the second pulse signal, so that the output of the switching power supply 400 is expected and is more stable.
With continued reference to fig. 4, in some embodiments of the present invention, the first amplifying circuit 500 may include a first error amplifier EA1, a non-inverting input terminal of the first error amplifier EA1 is connected to a first reference voltage, an inverting input terminal of the first error amplifier EA1 is connected to a feedback output voltage, and an output terminal of the first error amplifier EA1 outputs a first amplified voltage; the second amplifying circuit 600 may include a second error amplifier EA2, a non-inverting input terminal of the second error amplifier EA2 is connected to the first amplifying voltage, an inverting input terminal of the second error amplifier EA2 is connected to the third reference voltage, and an output terminal of the second error amplifier EA2 outputs the second amplifying voltage.
In some embodiments, the output terminal of the first error amplifier EA1 is electrically connected to the clamping circuit 140, and the clamping circuit 140 clamps the output voltage of the first error amplifier EA 1. The output terminal of the second error amplifier EA2 is electrically connected to the second pulse circuit 200, and the second pulse circuit 200 receives the second amplified voltage and determines the duty cycle according to the second amplified voltage. The second pulse circuit 200 may be a pulse modulation signal modulation circuit, and the pulse modulation signal modulation circuit and the principle are mature technologies, which are not described herein.
In the present embodiment, when the output voltage of the switching power supply 400 becomes large, VC1 decreases when the feedback output voltage is greater than the first reference voltage, and the output voltage decreases in a negative feedback form through loop control; when the output voltage of the switching power supply 400 becomes smaller and the feedback output voltage is smaller than the first reference voltage, VC1 increases, and the output voltage is increased in a negative feedback manner through loop control, and ripple of the output voltage may vary according to a variation in load size. The first error amplifier EA1 amplifies the difference between the first reference voltage and the feedback output voltage, and outputs the first amplified voltage VC1, so that VC1 reflects the difference between the output first reference voltage and the feedback output voltage, and indirectly reflects the magnitude of the load current, so that control of the light load operation mode can be achieved through control of the VC1 signal.
In a second aspect, the present invention provides an electronic device comprising a switching power supply and a switching power supply control circuit according to any one of the preceding embodiments, the switching power supply control circuit being electrically connected to the switching power supply. The specific structure of the switching power supply control circuit can be referred to the foregoing.
According to the electronic equipment, the working frequency of the inductive current is limited above the target frequency under the control of the switching power supply control circuit and is not in the sound frequency range which can be heard by human ears, so that the user experience is improved. In addition, the electronic device of the present invention may adopt the technical solutions in the above embodiments, so that the electronic device of the present invention also has corresponding technical effects, and will not be described in detail herein.
The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged, as appropriate, such that embodiments of the present invention may be implemented in sequences other than those illustrated or described herein, and that the objects identified by "first," "second," etc. are generally of a type, and are not limited to the number of objects, such as the first object may be one or more. Furthermore, in the description and claims, "and/or" means at least one of the connected objects, and the character "/", generally means that the associated object is an "or" relationship.
In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.
Claims (6)
1. A switching power supply control circuit, characterized in that the switching power supply control circuit comprises:
a first pulse circuit configured to provide a first pulse signal;
the timing circuit is electrically connected with the first pulse circuit and is configured to send a timing signal to the first pulse circuit when the first period duration of the first pulse signal reaches the target period duration, so that the first pulse circuit inverts the level of the first pulse signal according to the timing signal;
a second pulse circuit electrically connected to the first pulse circuit and the switching power supply, respectively, and configured to determine a second period duration based on the first period duration of the first pulse signal, so as to generate a second pulse signal having the second period duration, the second pulse signal being used for driving the switching power supply;
the switching power supply control circuit further includes:
the first amplifying circuit is electrically connected with the switching power supply and is configured to compare the feedback output voltage of the switching power supply with a first reference voltage and generate a first amplifying voltage based on a comparison result;
the first pulse circuit is electrically connected with the first amplifying circuit and is further configured to compare the first amplifying voltage with a second reference voltage and provide the first pulse signal based on a comparison result;
the first pulse circuit includes:
a voltage circuit having a first voltage output configured to provide a first voltage and a second voltage output configured to provide a second voltage, the first voltage and the second voltage having different voltage values;
the first input end of the first switch is electrically connected with the first voltage output end, and the second input end of the first switch is electrically connected with the second voltage output end;
the positive input end of the comparator is electrically connected with the output end of the first switch so as to be connected with the second reference voltage, the negative input end of the comparator is electrically connected with the first amplifying circuit so as to be connected with the first amplifying voltage, and the output end of the comparator outputs the first pulse signal;
the timing circuit is electrically connected with the control end of the first switch and is configured to control the output end of the first switch to be communicated with the first input end of the first switch or the output end of the first switch to be communicated with the second input end of the first switch;
the voltage circuit also has a third voltage output configured to provide a third voltage and a fourth voltage output configured to provide a fourth voltage, the third voltage and the fourth voltage having different voltage values;
the first pulse circuit further includes:
the first input end of the second switch is electrically connected with the third voltage output end, and the second input end of the second switch is electrically connected with the fourth voltage output end;
the input end of the clamping circuit is electrically connected with the output end of the second switch, and the output end of the clamping circuit is electrically connected with the first amplifying circuit so as to clamp the first amplifying voltage;
the timing circuit is further electrically connected with the control end of the second switch and is further configured to control the output end of the second switch to be communicated with the first input end of the second switch or the output end of the second switch to be communicated with the second input end of the second switch;
the switching power supply control circuit further includes:
the second amplifying circuit is electrically connected with the first amplifying circuit and is configured to compare the first amplifying voltage with a third reference voltage, and generate a second amplifying voltage based on a comparison result, wherein the third reference voltage represents an output current value of the switching power supply;
the second pulse circuit is further electrically connected to the second amplifying circuit and is further configured to determine a duty cycle based on the second amplifying voltage, and determine a second period duration based on the first period duration, so as to generate a second pulse signal having the duty cycle and the second period duration.
2. The switching power supply control circuit according to claim 1, wherein the first voltage is greater than the third voltage, the third voltage is greater than the second voltage, and the second voltage is greater than the fourth voltage;
the timing circuit is configured to control the first switch to switch from accessing the first voltage to accessing the second voltage and control the second switch to switch from accessing the third voltage to accessing the fourth voltage when the first period duration of the first pulse signal reaches a target period duration.
3. The switching power supply control circuit according to claim 2, wherein the timing circuit is electrically connected to an output terminal of the comparator, the timing circuit being configured to start timing when a falling edge of the first pulse signal is detected.
4. A switching power supply control circuit according to any one of claims 1 to 3, wherein the first amplifying circuit comprises a first error amplifier, a non-inverting input terminal of the first error amplifier being connected to the first reference voltage, an inverting input terminal of the first error amplifier being connected to the feedback output voltage, an output terminal of the first error amplifier outputting the first amplified voltage;
the second amplifying circuit comprises a second error amplifier, the non-inverting input end of the second error amplifier is connected with the first amplifying voltage, the inverting input end of the second error amplifier is connected with the third reference voltage, and the output end of the second error amplifier outputs the second amplifying voltage.
5. A switching power supply control circuit according to any one of claims 1 to 3, wherein the first period duration is equal to the second period duration and the target period duration is less than or equal to 40 μs.
6. An electronic device comprising a switching power supply and a switching power supply control circuit according to any one of claims 1-5, the switching power supply control circuit being electrically connected to the switching power supply.
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| CN101667782A (en) * | 2009-09-01 | 2010-03-10 | 成都芯源系统有限公司 | Switching power supply and control method thereof |
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| US7652461B2 (en) * | 2004-12-03 | 2010-01-26 | Texas Instruments Incorporated | High efficiency power converter operating free of an audible frequency range |
| CN101834522B (en) * | 2009-03-12 | 2012-12-12 | 登丰微电子股份有限公司 | Switching circuit and switching controller with anti-noise function |
| CN103683868B (en) * | 2013-12-25 | 2016-08-24 | 矽力杰半导体技术(杭州)有限公司 | Switching power source control circuit, Switching Power Supply and control method thereof |
| EP2985900B1 (en) * | 2014-08-14 | 2019-01-30 | Dialog Semiconductor (UK) Limited | Digital pulse skipping modulation for buck converter with auto-transition to pulse frequency modulation (PFM) |
| CN113162372B (en) * | 2020-12-31 | 2022-03-22 | 成都芯源系统有限公司 | Quasi-resonance controlled switch converter, controller and control method thereof |
| CN113691133B (en) * | 2021-08-25 | 2023-09-01 | 上海南芯半导体科技股份有限公司 | BUCK-BOOST with high-precision low-ripple light-load working mode |
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| CN101667782A (en) * | 2009-09-01 | 2010-03-10 | 成都芯源系统有限公司 | Switching power supply and control method thereof |
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