Switching power supply circuit capable of switching modulation modes

Abstract

The invention discloses a switching power supply circuit capable of switching modulation modes, the switching power supply circuit outputs an error output voltage Vc through the output end of an error amplifier EA, and a mapping relation curve between the error output voltage Vc and a pulse signal frequency F is preset in a pulse signal generation unit. A first voltage value Vc1 and a second voltage value Vc2 are set in the mapping relation curve, the first voltage value Vc1 corresponds to the minimum pulse signal frequency Fmin, and the second voltage value Vc2 corresponds to the maximum pulse signal frequency Fmax; and controlling the switching power supply to operate in different modes according to different error output voltage Vc values. The effect of automatically adjusting the working mode of the switching power supply based on the load state of the switching power supply is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, and in particular to a switching power supply circuit capable of switching modulation modes. Background Art

[0002] The switching power supply circuit in the prior art mainly has Burst mode, PWM mode and PFM mode for modulation. The control methods and specific circuits of the above three modes are different, and they can ensure high power conversion efficiency within the corresponding load range.

[0003] Burst mode refers to controlling the synchronous rectification switch to work continuously for several cycles and then shut down for several cycles according to the load conditions, thereby effectively reducing the switching loss in the converter system and reducing the static power consumption. Therefore, in the converter system, Burst mode is an efficient energy-saving mode under light load conditions.

[0004] Pulse width modulation (PWM) is a control method commonly used in switching power supplies. Especially when the switching frequency is very high, the dynamic response characteristics of the regulated power supply can be improved, the size and weight of the corresponding power components can be reduced, and the cost can be reduced. However, when the switch is running at a very high frequency, the switching loss of the power supply also increases accordingly. Especially when the load is light, the switching loss dominates, making the efficiency under light load usually less than 50%. In order to extend the battery life of portable electronic devices, it is hoped to improve the power conversion efficiency of the power supply under light load during design. In this way, the power consumption of portable devices can be reduced during long-term light load standby.

[0005] Pulse frequency modulation (PFM) is another control method for switching power supplies. Its equivalent switching frequency decreases as the load current decreases, so it can reduce the switching loss of the power supply under light load. However, under high current, its dynamic response is not as fast as pulse width modulation. In order to maintain dynamic response under heavy load while maintaining high efficiency under light load, the solution that can be adopted is to use pulse width modulation under heavy load and pulse frequency modulation under light load. This method requires the power supply to smoothly switch between pulse width modulation and pulse frequency modulation when the load current changes slowly, and reduce noise interference. When the load changes rapidly and dynamically, the control circuit must be able to ensure that the conversion between the two modes is fast and accurate, and maintain good dynamic response characteristics, thereby reducing the required output capacitance value to achieve the purpose of reducing the size, weight and cost of the power supply.

[0006] However, the above-mentioned different modulation control modes all need to be implemented using different loop control circuits, and all need to be implemented based on analog circuits. For example, if you want to switch from PWM mode to PFM mode, you need an additional precise voltage-controlled oscillator to generate a frequency signal that changes with the load.

[0007] It can be seen that a new switching power supply circuit with switchable modulation modes is needed in this field, which can realize flexible switching of the switching power supply modulation mode through a digital analog hybrid circuit and automatically switch and select the adjustment mode according to the actual load conditions. Summary of the invention

[0008] The present invention provides a switching power supply circuit capable of switching modulation modes. The switching power supply loop compensation circuit adjusts the switching power supply circuit to operate in different working modes by setting corresponding pulse frequencies for different error output voltage values, thereby realizing the switching of the working mode of the switching power supply based on the load state.

[0009] Based on the above technical purpose, the present invention provides a switching power supply circuit capable of switching modulation modes, which comprises: an error amplifier EA, a comparator operator CMP, an ADC unit and a pulse signal generating unit;

[0010] Also includes the output voltage V of the switching power supply circuit out Divide the voltage to generate the output voltage V out_div The output voltage V out_div The reference voltage V is input to the inverting input terminal of the error amplifier EA and the non-inverting input terminal of the error amplifier EA. ref , the output terminal of the error amplifier EA outputs an error output voltage V c , and the output end of the error amplifier EA is connected to the inverting input end of the comparator operator CMP;

[0011] The error output voltage V c At the same time, the analog signal is input to the ADC unit to convert the analog signal into a digital signal, and the ADC unit inputs the converted digital signal to the pulse signal generating unit;

[0012] The pulse signal generating unit is a digital signal processing unit, which is pre-set with an error output voltage V c and the pulse signal frequency F, wherein the mapping relationship curve is provided with a first voltage value V c1 and the second voltage value V c2 , where the first voltage value V c1 Corresponding to the minimum pulse signal frequency F min , the second voltage value V c2 Corresponding maximum pulse signal frequency F max ;

[0013] When the error output voltage V c At the first voltage value V c1 and the second voltage value V c2When the switching power supply enters the PFM modulation mode, the error output voltage V c It is in linear correspondence with the pulse signal frequency F;

[0014] When the error output voltage V c Greater than or equal to the second voltage value V c2 When the pulse signal frequency F of the pulse signal generated by the pulse signal generating unit is fixed to the maximum pulse signal frequency F max ; And the switching power supply enters PWM modulation mode;

[0015] When the error output voltage V c Less than or equal to the first voltage value V c1 When the pulse signal frequency F of the pulse signal generated by the pulse signal generating unit is fixed to the minimum pulse signal frequency F min ; and the switching power supply enters PWM modulation mode.

[0016] In one embodiment, the minimum pulse signal frequency F min Set above 20kHz.

[0017] In one embodiment, the mapping relationship curve is further provided with a third voltage value V c3 , the third voltage value V c3 , which is less than the first voltage value V c1 , when the error output voltage V c Less than or equal to the third voltage value V c3 When the pulse signal frequency F of the pulse signal generated by the pulse signal generating unit is fixed to the minimum pulse signal frequency F min ; and the switching power supply enters the Burst modulation mode.

[0018] In one embodiment, the voltage dividing unit includes a first resistor and a second resistor, the first resistor and the second resistor are connected in series, and a first end of the first resistor is connected to an output voltage V out The second end of the first resistor is connected to the first end of the second resistor, and the second end of the second resistor is grounded. The output voltage V is outputted by the second end of the first resistor. out_div .

[0019] In one embodiment, the switching power supply circuit further includes: an RS trigger, a switch tube N1, and a sampling voltage generating unit; the S terminal of the RS trigger inputs the pulse signal generated by the pulse signal generating unit, the R terminal of the RS trigger inputs the comparison signal output by the comparator operator CMP, the Q output terminal of the RS trigger is connected to the gate of the switch tube N1 to control the conduction of the switch tube N1, the sampling voltage generating unit is connected across the source and drain of the switch tube N1, and the sampling voltage generating unit generates a sampling voltage V according to the conduction current of the switch tube N1. sns .

[0020] In one embodiment, the switching power supply circuit capable of switching modulation modes further comprises an adder, wherein the adder superimposes the sampling voltage V sns and the external input slope compensation voltage V slope , and input the superimposed result to the non-inverting input terminal of the comparator operator CMP.

[0021] In one embodiment, the switching power supply circuit capable of switching modulation mode further comprises an inductor element and a diode element, wherein the first end of the inductor element is connected to the input voltage Vin, the second end of the inductor element is connected to the anode of the diode element, and the cathode of the diode element outputs the output voltage V of the switching power supply circuit. out .

[0022] Compared with the prior art, one or more embodiments of the present invention may have the following advantages:

[0023] The present invention digitizes the error output voltage and matches different pulse frequencies according to the value of the error output voltage to generate a mapping curve, thereby being able to adjust the pulse frequency according to the load state and control the switching power supply to enter different working modes.

[0024] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 It is a schematic diagram of the structure of a switching power supply circuit capable of switching modulation modes of the present invention;

[0027] Figure 2is the error output voltage V of the present invention c Schematic diagram of the curve with pulse signal frequency F. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings.

[0029] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not indicate that the present invention necessarily has the first element, component, region, layer or part.

[0030] Spatially relative terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used here for convenience of description to describe the relationship between an element or feature shown in the figure and other elements or features. It should be understood that in addition to the orientation shown in the figure, the spatial relationship terms are intended to also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is turned over, then the elements or features described as "under other elements" or "under it" or "under it" will be oriented as "on" other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device can be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0031] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0032] Example

[0033] like Figure 1 As shown, the switching power supply circuit capable of switching modulation modes of the present invention comprises: an error amplifier EA, a comparator operator CMP, an RS trigger, a switch tube N1, a sampling voltage generating unit, an ADC unit and a pulse signal generating unit.

[0034] The switching power supply circuit of the present invention can switch the modulation mode further includes: an output voltage V out Divide the voltage to generate the output voltage V out_div The voltage divider unit.

[0035] Among them, the output voltage is divided into V out_div The reference voltage V is input to the inverting input terminal of the error amplifier EA and the non-inverting input terminal of the error amplifier EA. ref , the output terminal of the error amplifier EA outputs an error output voltage V c , and the output end of the error amplifier EA is connected to the inverting input end of the comparator operator CMP.

[0036] The reference voltage V ref By external input, it affects the output voltage V out size.

[0037] The error output voltage V c At the same time, the analog signal is input to the ADC unit to convert the analog signal into a digital signal, and the ADC unit inputs the converted digital signal to the pulse signal generating unit.

[0038] like Figure 2 As shown, the pulse signal generating unit of the present invention is a digital signal processing unit, in which an error output voltage V is preset. c and the pulse signal frequency F, wherein the mapping relationship curve is provided with a first voltage value V c1 and the second voltage value V c2 , where the first voltage value Vc1 Corresponding to the minimum pulse signal frequency F min , the second voltage value V c2 Corresponding maximum pulse signal frequency F max When the error output voltage V c At the first voltage value V c1 and the second voltage value V c2 When the switching power supply enters the PFM modulation mode, the error output voltage V c It is linearly related to the pulse signal frequency F, that is, as the error output voltage V c As changes, the pulse signal frequency F of the pulse signal generated by the pulse signal generating unit changes linearly accordingly.

[0039] When the error output voltage V c Greater than or equal to the second voltage value V c2 When the pulse signal frequency F of the pulse signal generated by the pulse signal generating unit is fixed to the maximum pulse signal frequency F max . And the switching power supply enters the PWM modulation mode.

[0040] When the error output voltage V c Less than or equal to the first voltage value V c1 When the pulse signal frequency F of the pulse signal generated by the pulse signal generating unit is fixed to the minimum pulse signal frequency F min . And the switching power supply enters the PWM modulation mode.

[0041] In order to prevent the occurrence of noise audible to human ears, the minimum pulse signal frequency F min Set above 20kHz.

[0042] In the present invention, the mapping relationship curve is also provided with a third voltage value V c3 , the third voltage value V c3 , which is less than the first voltage value V c1 , when the error output voltage V c Less than or equal to the third voltage value V c3 When the pulse signal frequency F of the pulse signal generated by the pulse signal generating unit is fixed to the minimum pulse signal frequency F min And the switching power supply enters the Burst modulation mode, that is, the pulse signal generated by the pulse signal generating unit is not continuous, but a pulse signal of a predetermined duration is output at intervals of a predetermined duration.

[0043] In the present invention, the S terminal of the RS trigger inputs the pulse signal generated by the pulse signal generating unit, the R terminal of the RS trigger inputs the comparison signal output by the comparator operator CMP, the Q output terminal of the RS trigger is connected to the gate of the switch tube N1 to control the conduction of the switch tube N1, the sampling voltage generating unit is connected across the source and drain of the switch tube N1, and the sampling voltage generating unit generates a sampling voltage V according to the conduction current of the switch tube N1. sns .

[0044] In the present invention, the switching power supply circuit capable of switching modulation modes further comprises an adder, wherein the adder superimposes the sampling voltage V sns and the external input slope compensation voltage V slope , and input the superimposed result to the non-inverting input terminal of the comparator operator CMP.

[0045] In the present invention, the switching power supply circuit capable of switching modulation modes further comprises an inductor element and a diode element, wherein the first end of the inductor element is connected to the input voltage Vin, the second end of the inductor element is connected to the anode of the diode element, and the cathode of the diode element outputs the output voltage V of the switching power supply circuit. out .

[0046] The drain of the switch tube N1 is connected to the anode of the diode element, and the source of the switch tube N1 is grounded.

[0047] The voltage dividing unit includes a first resistor and a second resistor, the first resistor and the second resistor are connected in series, and a first end of the first resistor is connected to an output voltage V of the switching power supply circuit out The second end of the first resistor is connected to the first end of the second resistor, and the second end of the second resistor is grounded. The output voltage V is outputted by the second end of the first resistor. out_div .

[0048] In the present invention, the error amplifier EA divides the output voltage into V out_div and reference voltage V ref Compare and amplify to generate error output voltage V c signal, when the entire switching power supply circuit system reaches stability, the output voltage is divided into V out_div and reference voltage V ref Therefore, by adjusting the voltage division ratio of the first resistor R1 and the second resistor R2, different output voltages V out , that is, V out =V ref / R2*(R1+R2). The error amplifier EA generates an error output voltage V cThe signal has two functions, one is as the input of the comparator operator CMP, and the other is transmitted to the pulse signal generation unit after conversion by the ADC unit; when the external load becomes heavier, the error output voltage V c becomes larger, otherwise the error output voltage V c The comparator operator CMP is a peak voltage comparator, and its inverting input terminal is the error output voltage V c Voltage signal, the non-inverting input terminal is the sampling voltage signal V of the switch tube N1 SNS and the slope compensation signal V SLOPE The superimposed signal, when V SNS +V SLOPE >VC, the output of the comparator operator CMP changes from 0 to 1 and is sent to the R terminal of the RS trigger, resetting the output of the RS trigger to 0, so that the N1 tube is turned off; the S terminal of the RS trigger is provided by the pulse signal generation unit. The pulse signal generation unit outputs a voltage V according to different errors. c The size of the switch N1 is changed to provide pulse signals of different frequencies. When the pulse signal is high, the RS trigger output is set to 1, and the switch N1 is turned on. The switch N1 is turned on and off in this way, transferring energy from the input voltage V in The output voltage V is output through the inductor element L and the diode element D. out .

[0049] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A switching power supply circuit capable of switching modulation modes, characterized in that: It includes: Error amplifier EA, comparator operator CMP, ADC unit and pulse signal generating unit; Also includes the output voltage V of the switching power supply circuit out Divide the voltage to generate the output voltage V out_div The output voltage is divided into V out_div The reference voltage V is input to the inverting input terminal of the error amplifier EA and the non-inverting input terminal of the error amplifier EA. ref , the output terminal of the error amplifier EA outputs an error output voltage V c , and the output end of the error amplifier EA is connected to the inverting input end of the comparator operator CMP; The error output voltage V c At the same time, the analog signal is input to the ADC unit to convert the analog signal into a digital signal, and the ADC unit inputs the converted digital signal to the pulse signal generating unit; The pulse signal generating unit is a digital signal processing unit, which is pre-set with an error output voltage V c and the pulse signal frequency F, wherein the mapping relationship curve is provided with a first voltage value V c1 and the second voltage value V c2 , where the first voltage value V c1 Corresponding to the minimum pulse signal frequency F min , the second voltage value V c2 Corresponding maximum pulse signal frequency F max ; When the error output voltage V c At the first voltage value V c1 and the second voltage value V c2 When the switching power supply enters the PFM modulation mode, the error output voltage V c It is in linear correspondence with the pulse signal frequency F; When the error output voltage V c Greater than or equal to the second voltage value V c2 When the pulse signal frequency F of the pulse signal generated by the pulse signal generating unit is fixed to the maximum pulse signal frequency F max ; And the switching power supply enters PWM modulation mode; When the error output voltage V c Less than or equal to the first voltage value V c1 When the pulse signal frequency F of the pulse signal generated by the pulse signal generating unit is fixed to the minimum pulse signal frequency F min ; and the switching power supply enters PWM modulation mode.

2. The switching power supply circuit according to claim 1, characterized in that: The minimum pulse signal frequency F min Set above 20kHz.

3. The switching power supply circuit according to claim 1, characterized in that: The mapping relationship curve is also provided with a third voltage value V c3 , the third voltage value V c3 , which is less than the first voltage value V c1 , when the error output voltage V c Less than or equal to the third voltage value V c3 When the pulse signal frequency F of the pulse signal generated by the pulse signal generating unit is fixed to the minimum pulse signal frequency F min ; and the switching power supply enters the Burst modulation mode.

4. The switching power supply circuit according to claim 1, characterized in that: The voltage dividing unit includes a first resistor and a second resistor, the first resistor and the second resistor are connected in series, and a first end of the first resistor is connected to an output voltage V of the switching power supply circuit out The second end of the first resistor is connected to the first end of the second resistor, and the second end of the second resistor is grounded; the output voltage V is outputted by the second end of the first resistor out_div .

5. The switching power supply circuit according to claim 1, characterized in that: The switching power supply circuit further includes: an RS trigger, a switch tube N1, and a sampling voltage generating unit; the S terminal of the RS trigger inputs a pulse signal generated by the pulse signal generating unit, the R terminal of the RS trigger inputs a comparison signal output by a comparator operator CMP, the Q output terminal of the RS trigger is connected to the gate of the switch tube N1 to control the conduction of the switch tube N1, the sampling voltage generating unit is connected across the source and drain of the switch tube N1, and the sampling voltage generating unit generates a sampling voltage V according to the conduction current of the switch tube N1. sns .

6. The switching power supply circuit according to claim 5, characterized in that: The switching power supply circuit capable of switching modulation modes further comprises an adder, wherein the adder superimposes the sampling voltage V sns and the external input slope compensation voltage V slope , and input the superimposed result to the non-inverting input terminal of the comparator operator CMP.

7. The switching power supply circuit according to claim 1, characterized in that: The switching power supply circuit capable of switching modulation modes further comprises an inductor element and a diode element, wherein the first end of the inductor element is connected to the input voltage Vin, the second end of the inductor element is connected to the anode of the diode element, and the cathode of the diode element outputs the output voltage V of the switching power supply circuit. out .

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