CN115864836A - Switching power supply control circuit and electronic equipment - Google Patents
Switching power supply control circuit and electronic equipment Download PDFInfo
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- CN115864836A CN115864836A CN202310050195.XA CN202310050195A CN115864836A CN 115864836 A CN115864836 A CN 115864836A CN 202310050195 A CN202310050195 A CN 202310050195A CN 115864836 A CN115864836 A CN 115864836A
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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; a timing circuit configured to transmit a timing signal to the first pulse circuit when a first period duration of the first pulse signal reaches a target period duration, so that the first pulse circuit inverts a level of the first pulse signal according to the timing signal; 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 the inductive current is not in the audible frequency range of 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
Generally, when the switching power supply operates in a light load mode, the switching power supply system intermittently adjusts the inductor current according to the load. Normally, the frequency range of sound that can be heard by the human ear is between 20Hz and 20KHz, so when the intermittent operating frequency of the inductor current is between 20Hz and 20KHz, the human ear may hear the inductor squeal in the switching power supply circuit. This phenomenon occurs in many electronic products, which makes the otherwise silent system appear slightly loud, and seriously affects the user's use.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides the switching power supply control circuit and the electronic equipment, the intermittent working frequency of the inductive current is not in the audible frequency range of human ears, and the user experience is improved.
In a first aspect, the present invention provides a switching power supply control circuit, including: a first pulse circuit configured to provide a first pulse signal; a timing circuit electrically connected to the first pulse circuit and configured to transmit a timing signal to the first pulse circuit when a first cycle duration of the first pulse signal reaches a target cycle duration, so that the first pulse circuit inverts a level of the first pulse signal according to the timing signal; and 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 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 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, the first period duration is prevented from being too long, the second period duration of the second pulse signal is controlled, the switching frequency of the switching power supply is further controlled, the intermittent working frequency of the inductive current is limited above the target frequency, the inductive current is not in the audible frequency range of human ears, and user experience is improved.
According to an 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 the comparison result; the first pulse circuit is electrically connected with the first amplifying circuit and is also configured to compare the first amplifying voltage with a 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 and second voltages 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 phase input end of the comparator is electrically connected with the output end of the first switch so as to be connected with a second reference voltage, the negative phase input end of the comparator is electrically connected with the first amplifying circuit so as to be connected with a 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 an 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: a first input end of the second switch is electrically connected with the third voltage output end, and a 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; and 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 in the first voltage to switch in the second voltage and control the second switch to switch in the third voltage to switch in the fourth voltage when the first period duration of the first pulse signal reaches the target period duration.
According to one embodiment of the present 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 an 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, and the third reference voltage represents the output current value of the switching power supply; a second pulse circuit, also electrically connected to the second amplification circuit, is further configured to determine a duty cycle based on the second amplified voltage and a second cycle duration based on the first cycle duration to generate a second pulse signal having the duty cycle and the second cycle 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, a positive phase input end of the second error amplifier is connected with the first amplifying voltage, a negative phase input end of the second error amplifier is connected with the third reference voltage, and an 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 μ s.
In a second aspect, the 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, the intermittent working frequency of the inductive current of the switching power supply is limited above the target frequency under the control of the switching power supply control circuit, and is not in the audible frequency range of 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 above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic structural diagram of a switching power supply control circuit according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a waveform of an inductor current provided by an embodiment of the present invention;
fig. 3 is a second schematic structural diagram of a switching power supply control circuit according to an embodiment of the present invention;
fig. 4 is a third schematic structural 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 the switching power supply control circuit according to the embodiment of the present invention.
Reference numerals:
the first pulse circuit 100, the voltage circuit 110, the first voltage output end 111, the second voltage output end 112, the third voltage output end 113, the fourth voltage output end 114, the first switch 120, the second switch 130, and the clamping circuit 140;
a second pulse circuit 200;
a timing circuit 300;
a switching power supply 400;
a first amplification circuit 500;
a second amplification circuit 600;
a comparator COMP, a first error amplifier EA1, a second error amplifier EA2.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present 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 timing 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 transmit 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 a gate of the MOS transistor to apply the second pulse signal to the MOS transistor. The second pulse signal may include a high level part and a low level part, 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 thereto and turned on when a low level is applied thereto. The specific structure and principle of the switching power supply 400 are well-established, and the detailed description of the embodiment is omitted 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 normally operated in the discontinuous mode when it is operated in the light load mode. The power switch tube is switched on and then switched off in a pilot mode in one period, and the inductive current rises during the switching-on period of the power switch tube and continuously drops to zero during the switching-off period and is kept. The output voltage of the switching power supply 400 rises while the inductor current is greater than zero, and falls while the inductor current remains zero. One duty cycle of the inductor current may rise from zero to the next, which corresponds to the actual time period between the closing instant and the next closing instant of the power switch tube.
In some embodiments, the second pulse circuit 200 may integrate pulse width modulation functionality and pulse frequency modulation functionality. The second pulse circuit 200 may generate a pulse modulation signal with a variable duty ratio and a variable frequency, which is a 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 present invention, the first period duration may be equal to the second period duration, e.g., the first period duration and the second period duration are both 40 μ s. The second pulse circuit 200 may 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 cycle length may be less than or equal to 40 μ s. Taking the target period duration as 40 μ s as an example, the working frequency corresponding to 40 μ s is 25kHz, and the maximum value of the second period duration of the second pulse signal is 40 μ s; therefore, the switching frequency of the switching power supply 400 is 25kHz, and the operating frequency of the corresponding inductor current is 25kHz. And, the shorter the first period of the first pulse signal is, the higher the operating frequency of the inductor current is.
In some embodiments, the timing circuit 300 may include a timer. The timer may detect the first pulse signal and count the first pulse signal with a rising edge (or a falling edge) as a timing start time. If the timing time reaches the target cycle duration, and if the timing time reaches 40 mus, the timer sends a timing signal to the first pulse circuit 100; if the timer detects the rising edge (or the falling edge) again when the counted time does not reach the target period duration, the timer is restarted.
In the present embodiment, the first pulse circuit 100 controls the output first pulse signal to be inverted when receiving the timing signal, and causes the first pulse signal to perform the next cycle. That is, if the output first pulse signal is at a high level when the timing signal is received, the first pulse circuit 100 switches to output a low level; if the output first pulse signal is at a low level when the timing signal is received, 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, the first pulse circuit 100 may be provided with an inverter or the like, and the timing signal may be switched into or out of the loop by controlling the inverter to invert the level of the first pulse signal.
It will be appreciated that since the level of the first pulse signal is inverted, the second pulse signal is also inverted accordingly. Because the inversion moment is usually within the period of turning off the power switch tube, according to the control logic, the inverted level can control the power switch tube to be conducted, the inductive current starts to rise, and the inductive 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 first period duration is prevented from being too long, the second period duration of the second pulse signal is controlled, the switching frequency of the switching power supply 400 is controlled, the intermittent working frequency of the inductive current is limited above the target frequency, the inductive current 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 amplification circuit 500; the first amplification circuit 500 is electrically connected to the switching power supply 400, and the first amplification circuit 500 is configured to compare the feedback output voltage of the switching power supply 400 with a first reference voltage and generate a first amplification 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 a second reference voltage and provide a first pulse signal based on a comparison result.
It should be noted that the feedback output voltage can 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, which is transmitted to the first amplification circuit 500. The first amplification circuit 500 takes the voltage of the feedback signal as the 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 be indicative of a desired output voltage of the switching power supply 400, and the difference between the feedback output voltage and the first reference voltage may reflect a difference between an actual output and a 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 compare the feedback output voltage with a first reference voltage; by amplifying the difference, a first amplified voltage is obtained. Wherein amplifying the difference value may 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 when the first amplified voltage is greater than or equal to the second reference voltage, outputting a low level, and when the first amplified voltage is less than the second reference voltage, outputting a high level. The second reference voltage may be used to set a duty ratio of the first pulse signal, and a specific value thereof may be set according to a 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 squeal 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 111 and a second voltage output 112, the first voltage output 111 being configured to provide a first voltage, the second voltage output 112 being configured to provide 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; a positive phase input end of the comparator COMP is electrically connected with an output end of the first switch 120 to access the second reference voltage, a negative phase input end of the comparator COMP is electrically connected with the first amplifying circuit 500 to access the first amplifying voltage, and an output end of the comparator COMP outputs a 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 one input power into a plurality of different voltages, which may be formed by voltage division or 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 a first on state, the output terminal of the first switch 120 is in communication with the first input terminal; in the second conducting state, the output terminal of the first switch 120 is connected to the second input terminal. Generally, the first switch 120 mainly operates in the first conducting state or the second conducting 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 conducting state or the second conducting 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 this embodiment, when the second reference voltage is greater than or equal to the first amplification voltage, the output terminal of the comparator COMP is at a high level, and when the second reference voltage is less than the first amplification 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; a first input terminal of the second switch 130 is electrically connected to the third voltage output terminal 113, and a second input terminal of the second switch 130 is electrically connected to the fourth voltage output terminal 114; an input end of the clamp circuit 140 is electrically connected to an output end of the second switch 130, and an output end of the clamp circuit 140 is electrically connected to the first amplifying circuit 500 to clamp the first amplified 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 on state, the output terminal of the second switch 130 is connected to the first input terminal; in the second on state, the output terminal of the second switch 130 is connected to the second input terminal. Generally, the second switch 130 mainly operates in the first conducting state or the second conducting state, and the timing circuit 300 may generate a control signal to the control terminal of the first switch to control the second switch 130 to switch between the first conducting state or the second conducting state.
It is understood that the input voltage of the clamping circuit 140 is equal to the first voltage when the second switch 130 is in the first conducting state, and the input voltage of the clamping circuit 140 is equal to the second voltage when the second switch 130 is in the second conducting 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 can output a first timing signal VA1 and a second timing signal VA2, where the first timing signal VA1 is used for controlling the first switch 120 to switch, and the second timing signal VA2 is used for controlling 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 conducting state and the low level corresponds to the second conducting state; of course, the opposite is also possible.
In some embodiments, the clamping circuit 140 may clamp the first amplified voltage according to the input voltage. Here, clamping 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 illustration of the working principle of the switching power supply control circuit of the present invention, the following examples are proposed:
referring to fig. 5, vc1 denotes a first amplified voltage, V1 denotes a first voltage, V2 denotes a second voltage, V3 denotes a third voltage, V4 denotes a fourth voltage, and PFM denotes an output waveform of the comparator COMP. In an 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 large and the feedback output voltage is greater than the first reference voltage, VC1 decreases, and the switching power supply control circuit controls the switching power supply 400 to decrease the output 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 the present example, the timing circuit 300 is electrically connected to the output terminal of the comparator COMP, and the timing circuit 300 is 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 beginning of a control period, the second pulse circuit 200 switches the power switch tube in the switching power supply 400 from the non-switching state to the switching state at the falling edge of the first pulse signal, and the switching 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 on the first voltage to switching on the second voltage and the second switch 130 to switch from switching on the third voltage to switching on 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 conditions.
First case (section t1 in fig. 5): in the light load mode of the switching power supply 400, the timing circuit 300 starts timing with a falling edge of the PFM signal, and when the timing starts, the first amplified voltage VC1 is greater than the first voltage V1, and the output of the comparator COMP is at a low level. During the timing period, the first switch 120 and the second switch 130 are both switched to the first conducting state, and at this time, the second reference voltage is equal to the first voltage V1, and the clamping 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 drops below the first voltage V1, the comparator COMP outputs a high level. The first amplified voltage VC1 is then controlled by the clamp circuit 140 to be at the third voltage V3. 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 output of the comparator COMP changes to the 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): when the clamping voltage of the clamping circuit 140 changes to the fourth voltage V4, the first amplified voltage VC1 continues to drop, and when the first amplified voltage VC1 is smaller than the second voltage, the comparator COMP outputs a high level, and at this time, the timing circuit 300 switches both the first switch 120 and the second switch 130 to the first on state. As the output voltage becomes lower, 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 output of the comparator COMP becomes low level, and enters the next cycle, and the cycle time of the current cycle is less than the timing duration. Meanwhile, when the comparator COMP output changes from high level to low level, the timer circuit 300 restarts timing.
With continued reference to fig. 3, in some embodiments of the present invention, the switching power supply control circuit may further include a second amplification circuit 600; the second amplification circuit 600 is electrically connected to the first amplification circuit 500, the second amplification circuit 600 is configured to compare the first amplified voltage with a third reference voltage, and generate a second amplified 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 amplification circuit 600, and the second pulse circuit 200 is further configured to determine a duty cycle based on the second amplified voltage and a second cycle duration based on the first cycle duration to generate a second pulse signal having the duty cycle and the second cycle duration.
In some embodiments, the switching power supply control circuit may further include a current sampling circuit configured to sample the output current of the switching power supply 400 and convert the sampled output current into a feedback signal, which is transmitted to the second amplification circuit 600. The second amplification circuit 600 takes the voltage of the feedback signal as a third reference voltage.
In some embodiments, the second amplifying circuit 600 may perform a comparison by subtracting the first amplified voltage from a third reference voltage; by amplifying the difference, a second amplified voltage is obtained. Wherein amplifying the difference value may facilitate subsequent detection and identification.
In this embodiment, a voltage loop and a current loop are used to form a dual-loop control, the voltage loop serves as an outer loop to transmit an output to the current loop, the current loop serves as an inner loop, an output is formed 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 more stable.
With continued reference to fig. 4, in some embodiments of the 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 the first reference voltage, an inverting input terminal of the first error amplifier EA1 is connected to the feedback output voltage, and an output terminal of the first error amplifier EA1 outputs the 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 amplified 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 amplified 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. An 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 ratio according to the second amplified voltage. The second pulse circuit 200 may adopt a pulse modulation signal modulation circuit, which has a mature technology and a mature principle, and is not described herein again in this embodiment.
In the present embodiment, when the output voltage of the switching power supply 400 becomes large and the feedback output voltage is greater than the first reference voltage, VC1 decreases, decreasing the output voltage in a negative feedback manner through loop control; when the output voltage of the switching power supply 400 becomes small and the feedback output voltage is smaller than the first reference voltage, VC1 increases, the output voltage is increased in a negative feedback manner through loop control, and the ripple of the output voltage varies according to the change in the size of the load. 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 the difference between the output first reference voltage and the feedback output voltage is reflected by VC1, and the magnitude of the load current is also indirectly reflected, and thus the control of the light-load operating mode can be realized by controlling the VC1 signal.
In a second aspect, the 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 refer to the foregoing description.
According to the electronic equipment, the working frequency of the inductive current of the switching power supply is limited above the target frequency under the control of the switching power supply control circuit, and is not in the audible frequency range of 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, which are not described in detail herein.
The terms first, second and the like in the description and in the claims of the present invention are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that embodiments of the invention may be practiced other than those illustrated or described herein, and that the objects identified as "first," "second," etc. are generally a class of objects and do not limit the number of objects, e.g., a first object may be one or more. In addition, "and/or" in the specification and claims means at least one of connected objects, a character "/" generally means that a preceding and succeeding related objects are in an "or" relationship.
In the description of the present specification, reference to the description of "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like 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 present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. 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: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (10)
1. A switching power supply control circuit, comprising:
a first pulse circuit configured to provide a first pulse signal;
a timing circuit electrically connected to the first pulse circuit and configured to send a timing signal to the first pulse circuit when a first period duration of the first pulse signal reaches a target period duration, so that the first pulse circuit inverts a level of the first pulse signal according to the timing signal;
a second pulse circuit electrically connected to the first pulse circuit and a switching power supply, respectively, and 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.
2. The switching power supply control circuit according to claim 1, further comprising:
a first amplifying circuit electrically connected to the switching power supply, configured to compare a feedback output voltage of the switching power supply with a first reference voltage, and generate a first amplified 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 amplified voltage with a second reference voltage and provide the first pulse signal based on a comparison result.
3. The switching power supply control circuit according to claim 2, wherein the first pulse circuit comprises:
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 and second voltages having different voltage values;
a first switch, a first input end of which is electrically connected with the first voltage output end, and a second input end of which is electrically connected with the second voltage output end;
a positive phase 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, a negative phase 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 or the second input end.
4. The switching power supply control circuit of claim 3 wherein 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 and fourth voltages having different voltage values;
the first pulse circuit further includes:
a second switch, a first input end of the second switch being electrically connected to the third voltage output end, a second input end of the second switch being electrically connected to 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 amplified 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 or the second input end.
5. The switching power supply control circuit according to claim 4, 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 in the first voltage and the second switch to switch in the third voltage and the fourth voltage when a first period duration of the first pulse signal reaches a target period duration.
6. The switching power supply control circuit according to claim 5, wherein the timing circuit is electrically connected to the output terminal of the comparator, and the timing circuit is configured to start timing when a falling edge of the first pulse signal is detected.
7. The switching power supply control circuit according to any one of claims 2 to 6, further comprising:
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, and the third reference voltage represents the output current value of the switching power supply;
the second pulse circuit, also electrically coupled to the second amplification circuit, is further configured to determine a duty cycle based on the second amplified voltage and a second cycle duration based on the first cycle duration to generate a second pulse signal having the duty cycle and the second cycle duration.
8. The switching power supply control circuit according to claim 7, wherein the first amplifying circuit comprises a first error amplifier, a non-inverting input terminal of the first error amplifier is connected to the first reference voltage, an inverting input terminal of the first error amplifier is connected to the feedback output voltage, and an output terminal of the first error amplifier outputs the first amplified voltage;
the second amplifying circuit comprises a second error amplifier, a positive phase input end of the second error amplifier is connected to the first amplifying voltage, an inverted phase input end of the second error amplifier is connected to the third reference voltage, and an output end of the second error amplifier outputs the second amplifying voltage.
9. The switching power supply control circuit according to any of claims 1-6, wherein the first period duration is equal to the second period duration, and the target period duration is less than or equal to 40 μ β.
10. An electronic device characterized in that the electronic device comprises a switching power supply and a switching power supply control circuit according to any one of claims 1 to 9, the switching power supply control circuit being electrically connected to the switching power supply.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310050195.XA CN115864836B (en) | 2023-02-01 | 2023-02-01 | Switching power supply control circuit and electronic equipment |
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| CN202310050195.XA CN115864836B (en) | 2023-02-01 | 2023-02-01 | Switching power supply control circuit and electronic equipment |
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| CN115864836B CN115864836B (en) | 2023-05-12 |
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| CN115864836B (en) | 2023-05-12 |
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