Sampling circuit and dc-dc converter

Abstract

The application is suitable for the technical field of DC-DC converters, and provides a sampling circuit and a DC-DC converter. The sampling circuit comprises a sampling unit, an isolation unit and a pull-up unit. The sampling unit is connected in series between an input power supply and a comparison module, and is configured to output a first sampling voltage signal to the comparison module according to a modulation signal and an input voltage signal. The isolation unit is connected in series between the sampling unit and a conversion module, and is configured to output a second sampling voltage signal to the conversion module according to the first sampling voltage signal and the modulation signal. The pull-up unit is connected in series between the input power supply and the conversion module, and is configured to output a preset voltage to the conversion module according to the input voltage signal when the sampling unit does not output the first sampling voltage signal. The pull-up unit in the sampling circuit outputs the preset voltage to the conversion module when the sampling unit does not output the first sampling voltage signal, so that the establishment speed and accuracy of the second sampling voltage are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of DC-DC converters, and particularly relates to a sampling circuit and a DC-DC converter. BACKGROUND

[0002] The DC-DC converter is a DC conversion device for converting a fixed DC voltage into a variable DC voltage. The DC-DC converter comprises a sampling circuit, a comparison module and a conversion module. The conversion module is configured to convert an error amplification voltage signal output by the DC-DC converter into a sampling current signal. The comparison module is configured to compare a first sampling voltage signal with a switching node voltage signal, and output a modulation signal. The sampling circuit is configured to output a second sampling voltage signal to the conversion module according to the modulation signal and an input voltage signal output by an input power supply. When a switch tube in the sampling circuit is in an off state, the second sampling voltage signal output by the sampling circuit to the conversion module linearly decreases to zero, and a switch tube in the conversion module enters a linear region from a saturation region. When the switch tube in the sampling circuit is switched to an on state, the second sampling voltage signal output by the sampling circuit to the conversion module linearly increases from zero, and the switch tube in the conversion module enters the saturation region from the linear region. A certain time is required in this stage, which causes the conversion module to be unable to provide the sampling current in time when the switch tube in the sampling circuit is switched to the on state, resulting in a delay in the output of the second sampling voltage signal by the sampling circuit, and further affecting the accuracy of the modulation signal output by the comparison module. SUMMARY

[0003] The application provides a sampling circuit and a DC-DC converter, which can solve the problem that the conversion module in the DC-DC converter is unable to provide the sampling current in time, resulting in a delay in the output of the second sampling voltage signal by the sampling circuit, and further affecting the accuracy of the modulation signal output by the comparison module.

[0004] In a first aspect, an embodiment of the application provides a sampling circuit applied to a DC-DC converter. The DC-DC converter comprises a comparison module and a conversion module. The conversion module is configured to convert an error amplification voltage signal output by the DC-DC converter into a sampling current signal. The comparison module is configured to compare a first sampling voltage signal with a switching node voltage signal, and output a modulation signal. The DC-DC converter is configured to adjust the switching node voltage signal according to the modulation signal and an input voltage signal output by an input power supply. The sampling circuit comprises:

[0005] a sampling unit configured to be connected in series between the input power supply and the comparison module, and configured to output the first sampling voltage signal to the comparison module according to the modulation signal and the input voltage signal;

[0006] an isolation unit, connected in series between the sampling unit and the conversion module, and configured to output a second sampling voltage signal to the conversion module according to the first sampling voltage signal and the modulation signal; and

[0007] a pull-up unit, connected in series between the input power supply and the conversion module, and configured to output a preset voltage to the conversion module according to the input voltage signal when the sampling unit does not output the first sampling voltage signal.

[0008] In a possible implementation of the first aspect, the sampling unit includes a first switch tube connected in series, a drain of a first first switch tube is electrically connected with the input power supply, a source of an a-th first switch tube is electrically connected with the comparison module and the isolation unit respectively, and a gate of each of the first switch tubes receives the modulation signal, where a is a positive integer.

[0009] In a possible implementation of the first aspect, a source of a b-th first switch tube and a drain of a b+1-th first switch tube are electrically connected, where b is a positive integer and 1≤b

[0010] In a possible implementation of the first aspect, the isolation unit includes a second switch tube connected in series, a source of a first second switch tube is electrically connected with a source of the a-th first switch tube, a drain of a c-th second switch tube is electrically connected with the conversion module, and a gate of each of the second switch tubes receives the modulation signal, where c is a positive integer.

[0011] In a possible implementation of the first aspect, a source of a d-th second switch tube and a drain of a d+1-th second switch tube are electrically connected, where d is a positive integer and 1≤d

[0012] In a possible implementation of the first aspect, each of the first switch tubes and each of the second switch tubes is an N-type MOS tube.

[0013] In a possible implementation of the first aspect, the pull-up unit includes a third switch tube connected in series, a source of a first third switch tube is electrically connected with the input power supply, a drain of an e-th third switch tube is electrically connected with the conversion module, and a gate of each of the third switch tubes is electrically connected with a respective drain, where e is a positive integer.

[0014] In a possible implementation of the first aspect, a drain of a f-th third switch tube and a source of a f+1-th third switch tube are electrically connected, where f is a positive integer and 1≤f

[0015] In a possible implementation of the first aspect, all the third switch tubes are P-type MOS tubes.

[0016] In a second aspect, the embodiments of the present application provide a DC-DC converter, comprising the sampling circuit of any one of the first aspect.

[0017] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0018] The sampling circuit provided by the embodiments of the present application comprises a sampling unit, an isolation unit and a pull-up unit. The sampling unit is connected in series between an input power supply and a comparison module, and is configured to output a first sampling voltage signal to the comparison module and the isolation unit according to a modulation signal and an input voltage signal. The isolation unit is configured to output a second sampling voltage signal to a conversion module according to the first sampling voltage signal and the modulation signal. The comparison module is configured to compare the first sampling signal with a switch node voltage signal and output the modulation signal. When the modulation signal output by the comparison module is at a low level, the sampling unit cannot output the first sampling voltage signal to the isolation unit according to the modulation signal and the input voltage signal, and a pull-up unit connected in series between the input power supply and the conversion module is triggered. The pull-up unit outputs a preset voltage to the conversion module, so that a current mirror in the conversion module is always in a saturation region. When the modulation signal output by the comparison module is at a high level, the sampling unit can output the first sampling voltage signal to the isolation unit according to the modulation signal and the input voltage signal, and the isolation unit can output the second sampling voltage signal to the conversion module according to the first sampling voltage signal and the modulation signal. At this time, the input voltage of the conversion module is increased from the preset voltage to the second sampling voltage signal, thereby improving the establishment speed and accuracy of the second sampling voltage. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 is a principle block diagram of the sampling circuit provided by an embodiment of the present application;

[0021] Figure 2 is a principle block diagram of the DC-DC converter provided by an embodiment of the present application;

[0022] Figure 3 is a circuit principle diagram of the sampling circuit provided by an embodiment of the present application.

[0023] In the figure: 10, sampling unit; 20, isolation unit; 30, pull-up unit; 40, comparison module; 50, conversion module; 60, input power supply; 01, sampling circuit. DETAILED DESCRIPTION

[0024] In the following description, for the purposes of explanation and not limitation, specific details are set forth such as particular architectures, techniques, etc. in order to provide a thorough understanding of the embodiments of the application. However, it will be apparent to those skilled in the art that the application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods, devices, circuits, and

[0025] It is to be understood that the terminology "includes", "has", "holds", "contains" or variants thereof, when utilized within the present specification and claims, denotes the presence of the stated feature but not the exclusion after the limitation of the presence of one or more additional features, integers, steps, operations, elements, components and / or groups thereof.

[0026] It is also to be understood that the terminology "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items, and that the term "at least one of' denotes one, or a plurality of, or any combination of the listed items.

[0027] As used in the present specification and claims, the term "if' can be interpreted as meaning "when" or "once" or "in response to a determination" or "in response to a detection" depending on the context. Similarly, the phrase "if determined" or "if detected [the described condition or event]" can be interpreted as meaning "once determined" or "in response to a determination" or "once detected [the described condition or event]" or "in response to a detection [the described condition or event]" depending on the context.

[0028] In addition, in the description of the present specification and the appended claims, the terms "first", "second", "third", etc. are only used for differentiation of description and cannot be understood as indicating or implying relative importance.

[0029] Reference within the specification of this application to "one embodiment" or "some embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase "in one embodiment" or "in some embodiments" in various places within specified descriptions in this specification are not necessarily all referring to the same embodiment, however, can mean one or more but not all embodiments. The terms "including," "comprising," "featuring," and variations thereof are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Although the terms "comprise," "have," "include," or "contain" can be used in the specification, these terms are open-ended, and specifically do not exclude the presence of zero amount of the referenced item.

[0030] The conventional DC-DC converter includes a sampling circuit, a comparison module and a conversion module, the conversion module is used for converting the error amplification voltage signal output by the DC-DC converter into a sampling current signal, the comparison module is used for comparing the first sampling voltage signal and the switch node voltage signal, and outputting a modulation signal, and the sampling circuit is used for outputting a second sampling voltage signal to the conversion module according to the modulation signal and the input voltage signal output by the input power supply. When the switch tube in the sampling circuit is in an off state, the second sampling voltage signal output by the sampling circuit to the conversion module decreases to zero, and when the switch tube in the sampling circuit is in an on state, the second sampling voltage signal output by the sampling circuit to the conversion module increases from zero, and it takes a period of time for the second sampling voltage signal to stabilize. Therefore, the establishment speed of the second sampling voltage signal is slow and the voltage accuracy is poor.

[0031] Based on the above problems, the sampling circuit provided by the embodiments of the present application includes a sampling unit, an isolation unit and a pull-up unit. The sampling unit is connected in series between the input power supply and the comparison module, and is used for outputting a first sampling voltage signal to the comparison module and the isolation unit according to the modulation signal and the input voltage signal. The isolation unit is used for outputting a second sampling voltage signal to the conversion module according to the first sampling voltage signal and the modulation signal. The comparison module is used for comparing the first sampling signal and the switch node voltage signal, and outputting a modulation signal. When the modulation signal output by the comparison module is at a low level, the sampling unit cannot output the first sampling voltage signal to the isolation unit according to the modulation signal and the input voltage signal, and the pull-up unit connected in series between the input power supply and the conversion module is triggered, the pull-up unit outputs a preset voltage to the conversion module, so that the current mirror in the conversion module is always in the saturation region. When the modulation signal output by the comparison module is at a high level, the sampling unit can output the first sampling voltage signal to the isolation unit according to the modulation signal and the input voltage signal, and at the same time, the isolation unit can output the second sampling voltage signal to the conversion module according to the first sampling voltage signal and the modulation signal. At this time, the input voltage of the conversion module increases from the preset voltage to the second sampling voltage signal, thereby improving the establishment speed and accuracy of the second sampling voltage.

[0032] In order to illustrate the technical solutions described in the present application, specific embodiments are described below.

[0033] Figure 1 A principle block diagram of a sampling circuit 01 provided by an embodiment of the present application is shown. Referring to Figure 1 As shown, the sampling circuit 01 is applied to a DC-DC converter, the DC-DC converter includes a comparison module 40 and a conversion module 50, the conversion module 50 is used to convert an error amplification voltage signal Verr output by the DC-DC converter into a sampling current signal, the comparison module 40 is used to compare a first sampling voltage signal Vsen1 and a switching node voltage signal Vsw, and output a modulation signal, the DC-DC converter is used to adjust the switching node voltage signal Vsw according to the modulation signal and an input voltage signal Vin output by an input power supply 60, and the above-mentioned sampling circuit 01 includes:

[0034] a sampling unit 10, which is used to be connected in series between the input power supply 60 and the comparison module 40, and is also used to output the first sampling voltage signal Vsen1 to the comparison module 40 according to the modulation signal PWM and the input voltage signal Vin;

[0035] an isolation unit 20, which is used to be connected in series between the sampling unit 10 and the conversion module 50, and is also used to output a second sampling voltage signal Vsen2 to the conversion module 50 according to the first sampling voltage signal Vsen1 and the modulation signal;

[0036] a pull-up unit 30, which is used to be connected in series between the input power supply 60 and the conversion module 50, and is also used to output a preset voltage to the conversion module 50 according to the input voltage signal Vin when the sampling unit 10 does not output the first sampling voltage signal Vsen1.

[0037] Specifically, the sampling unit 10 is connected in series between the input power supply 60 and the comparison module 40, and is configured to output a first sampling voltage signal Vsen1 to the comparison module 40 and the isolation unit 20 according to the modulation signal and the input voltage signal Vin, and the isolation unit 20 is configured to output a second sampling voltage signal Vsen2 to the conversion module 50 according to the first sampling voltage signal Vsen1 and the modulation signal. The comparison module 40 is configured to compare the first sampling signal and the switching node voltage signal Vsw, and output the modulation signal. When the modulation signal output by the comparison module 40 is at a low level, the sampling unit 10 cannot output the first sampling voltage signal Vsen1 to the isolation unit 20 according to the modulation signal and the input voltage signal Vin, and the isolation unit 20 cannot output the second sampling voltage signal Vsen2 to the conversion module 50 according to the first sampling voltage signal Vsen1 and the modulation signal. At this time, the pull-up unit 30 connected in series between the input power supply 60 and the conversion module 50 is triggered, and the pull-up unit 30 outputs a preset voltage to the conversion module 50 when the sampling unit 10 does not output the first sampling voltage signal Vsen1, so that the switch in the conversion module is always in the saturation region. When the modulation signal output by the comparison module 40 is at a high level, the sampling unit 10 can output the first sampling voltage signal Vsen1 to the isolation unit 20 according to the modulation signal and the input voltage signal Vin, and the isolation unit 20 can output the second sampling voltage signal Vsen2 to the conversion module 50 according to the first sampling voltage signal Vsen1 and the modulation signal. At this time, the input voltage of the conversion module 50 is increased from the preset voltage to the second sampling voltage signal Vsen2, thereby improving the establishment speed and accuracy of the second sampling voltage.

[0038] It should be noted that, as shown in Figure 2 the modulation signal can be a PWM signal, and the sampling circuit 01 outputs the first sampling voltage signal Vsen1 to the comparison module 40 according to the input PWM signal and the input voltage signal Vin, and the comparison module 40 outputs the PWM signal according to the input first sampling voltage signal Vsen1 and the switching node voltage signal Vsw. At the same time, the sampling circuit 01 also outputs the second sampling voltage signal Vsen2 to the conversion module 50, and the conversion module 50 converts the input error amplification voltage signal Verr into a sampling current signal. The DC-DC converter adjusts the switching node voltage signal Vsw according to the PWM signal and the input voltage signal Vin.

[0039] For example, in order to facilitate the explanation of the whole process of regulating the switch node voltage signal Vsw by the DC-DC converter, the current adjustment period can be set, and the switch node voltage signal Vsw is defined as the first switch node voltage signal Vsw1. After the DC-DC converter regulates the first switch node voltage signal Vsw1 according to the PWM signal and the input voltage signal Vin, the signal output by the switch node is defined as the second switch node voltage signal Vsw2. It can be understood that after the second switch node voltage signal Vsw2 is output, the next adjustment period, the second switch node voltage signal Vsw2 is taken as the first switch node voltage signal Vsw1 in the above process.

[0040] It should be noted that the preset voltage value is less than the voltage value of the second sampling voltage signal Vsen2

[0041] In an embodiment of the present application, the sampling unit 10 includes a first switch tube in series. The drain electrode of the first first switch tube is electrically connected with the input power supply 60, the source electrode of the a-th first switch tube is electrically connected with the comparison module 40 and the isolation unit 20 respectively, and the gate electrode of all the first switch tubes receives the modulation signal, wherein a is a positive integer.

[0042] Specifically, the switch tubes in the sampling unit 10 are all defined as first switch tubes, and each first switch tube is in series. Among them, the drain electrode of the first first switch tube is electrically connected with the input power supply 60 and serves as the input end of the sampling unit 10, used for receiving the input voltage signal Vin output by the input power supply 60. The source electrode of the a-th first switch tube serves as the output end of the sampling unit 10, and outputs the first sampling voltage signal to the comparison module 40 and the isolation unit 20. At the same time, the gate electrode of all the first switch tubes receives the modulation signal, which can ensure that all the first switch tubes are turned on or turned off at the same time. When all the first switch tubes are turned on at the same time, the voltage value of the input voltage signal Vin of the sampling unit 10 is equal to or approximately equal to the voltage value of the first sampling voltage signal Vsen1 output by the sampling unit 10 to the isolation unit 20, that is, the total voltage drop of all the first switch tubes in the sampling unit 10 is very small or even zero, which can be ignored. When all the first switch tubes are turned off at the same time, the sampling unit 10 cannot output the first sampling voltage signal Vsen1 to the isolation unit 20 and the comparison module 40. At this time, the voltage value of the input voltage signal Vin of the sampling unit 10 is much greater than the voltage value of the first sampling voltage signal Vsen1 output by the sampling unit 10 to the isolation unit 20, that is, the total voltage drop of all the first switch tubes in the sampling unit 10 is very large, which can trigger the pull-up unit 30 to be turned on and output the preset voltage to the conversion module 50, so as to ensure that the conversion module 50 has a continuous input voltage, thereby improving the establishment speed and accuracy of the second sampling voltage.

[0043] It should be noted that designers can select an appropriate number of first switching transistors based on actual conditions, and can select an appropriate number of MOS transistors as the first switching transistors to meet the actual sampling requirements of the sampling unit 10. Furthermore, designers can also select the models of the first switching transistors based on actual requirements. For example, N-type MOS transistors can be selected to meet the high-voltage sampling requirements of the sampling unit 10.

[0044] For example, Figure 3 As shown, the sampling unit 10 includes three first switching transistors connected in series, M11, M12, and M13. M11 is the first first switching transistor, with its drain electrically connected to the input power supply 60 and serving as the input terminal of the sampling unit 10 for receiving the input voltage signal Vin output by the input power supply 60. M13 is the third first switching transistor, with its source electrically connected to the comparison module 40 and the isolation unit 20, respectively, and serving as the output terminal of the sampling unit 10 for outputting the first sampling voltage signal Vsen1 to the comparison module 40 and the isolation unit 20. Simultaneously, the gates of M11, M12, and M13 all receive modulation signals, ensuring that M11, M12, and M13 are simultaneously turned on or off. When M11, M12, and M13 are simultaneously turned on, the voltage value of the input voltage signal Vin of the sampling unit 10 is equal to or approximately equal to the voltage value of the first sampled voltage signal Vsen1 output by the sampling unit 10 to the isolation unit 20. This means that the total voltage drop across M11, M12, and M13 is very small or even zero, and can be ignored. When M11, M12, and M13 are simultaneously turned off, the sampling unit 10 is unable to output the first sampled voltage signal to the isolation unit 20 and the comparison module 40. In this case, the voltage value of the input voltage signal Vin of the sampling unit 10 is significantly greater than the voltage value of the first sampled voltage signal Vsen1 output by the sampling unit 10 to the isolation unit 20. This means that the total voltage drop across M11, M12, and M13 is significant, triggering the pull-up unit 30 to turn on and output a preset voltage to the conversion module 50. This ensures that the conversion module 50 receives a continuous input voltage, thereby improving the speed and accuracy of establishing the second sampled voltage.

[0045] It should be noted that M11, M12, and M13 are all N-type MOS transistors. Selecting an N-type MOS transistor allows the drain of M11 to be electrically connected to the input power supply 60 and receive the input voltage signal Vin output by the input power supply 60. When the input voltage signal Vin is a high voltage signal, the drain of M11 has a strong high voltage resistance capability, which can prevent M11 from being damaged when the high voltage signal is input to the sampling unit 10, thereby improving the reliability of the sampling circuit 01.

[0046] In one embodiment of the present application, the source of the bth first switch and the drain of the b+1th first switch are electrically connected, where b is a positive integer and 1≤b

[0047] Specifically, the source of the bth first switch and the drain of the b+1th first switch are electrically connected, so that all the first switches in the sampling unit 10 are connected in series. If b=1, the drain of the bth first switch is electrically connected with the input power supply 60 for receiving the input voltage signal Vin output by the input power supply 60; if b>1, the drain of the bth first switch is electrically connected with the source of the b-1th first switch for receiving the voltage signal output by the source of the b-1th first switch, and the drain of the b+1th first switch is electrically connected with the source of the bth first switch for receiving the voltage signal output by the source of the bth first switch.

[0048] For example, when the value of b is 2, the drain of the second first switch M12 is electrically connected with the source of the first first switch M11 for receiving the voltage signal output by the source of the first first switch M11, and the drain of the third first switch M13 is electrically connected with the source of the second first switch M12 for receiving the voltage signal output by the source of the second first switch M12.

[0049] It should be noted that, as shown in Figure 3 the value of a is 3 and the value of b is 2, at this time, the source and the drain of M12 can be interchanged, i.e., the source of M12 is electrically connected with the source of M11 for receiving the voltage signal output by the source of M11, and the drain of M13 is electrically connected with the drain of M12 for receiving the voltage signal output by the drain of M12.

[0050] In one embodiment of the present application, the isolation unit 20 includes c second switches connected in series, the source of the first second switch is electrically connected with the source of the a th first switch, the drain of the c th second switch is electrically connected with the conversion module 50, and the gate of all the second switches receives the modulation signal, where c is a positive integer.

[0051] Specifically, the switch tubes in the isolation unit 20 are all defined as second switch tubes, and each second switch tube is connected in series. The source electrode of the first second switch tube is electrically connected with the source electrode of the a-th first switch tube, and serves as the input end of the isolation unit 20, for receiving the first sampling voltage signal Vsen1 output by the sampling unit 10. The drain electrode of the c-th second switch tube serves as the output end of the isolation unit 20, for outputting the second sampling voltage signal Vsen2 to the conversion module 50. Meanwhile, the gate electrodes of all the second switch tubes receive the modulation signal, so as to ensure that all the second switch tubes are turned on or turned off at the same time. When all the first switch tubes and all the second switch tubes are turned on at the same time, the voltage value of the first sampling voltage signal Vsen1 output by the sampling unit 10 is equal to or approximately equal to the voltage value of the second sampling voltage signal Vsen2 output by the isolation unit 20 to the conversion module 50, that is, the total voltage drop of all the second switch tubes in the isolation unit 20 is very small or even zero, which can be ignored. When all the first switch tubes and all the second switch tubes are turned off at the same time, the sampling unit 10 cannot output the first sampling voltage signal Vsen1 to the isolation unit 20, and the isolation unit 20 cannot output the second sampling voltage signal Vsen2 to the conversion module 50. At this time, the voltage value of the input voltage signal Vin of the sampling unit 10 is much larger than the voltage value of the second sampling voltage signal Vsen2 output by the isolation unit 20 to the conversion module 50, that is, the total voltage drop of all the second switch tubes in the isolation unit 20 is very large, which can trigger the pull-up unit 30 to be turned on, output a preset voltage to the conversion module 50, and ensure that the conversion module 50 has a continuous input voltage, thereby improving the establishment speed and accuracy of the second sampling voltage.

[0052] It should be noted that the designer can select a proper number of second switch tubes according to the actual situation, and can select a proper number of MOS tubes as the second switch tubes to meet the actual needs of the isolation unit 20. Meanwhile, the designer can also select the type of the second switch tube according to the actual needs, for example, selecting an N-type MOS tube to meet the needs of high-voltage isolation of the isolation unit 20.

[0053] For example, Figure 3As shown, the isolation unit 20 includes three second switch tubes connected in series, M21, M22 and M23 are all second switch tubes. Among them, M21 is the first second switch tube, the source of M21 is electrically connected with the source of M13, and serves as the input end of the isolation unit 20, for receiving the first sampling voltage signal Vsen1 output by the sampling unit 10. M23 is the third second switch tube, the drain of M23 serves as the output end of the isolation unit 20, and outputs the second sampling voltage signal Vsen2 to the conversion module 50. At the same time, the gate of M21, the gate of M22 and the gate of M23 all receive the modulation signal, which can ensure that M21, M22 and M23 are turned on or turned off at the same time. When M11, M12, M13, M21, M22 and M23 are turned on at the same time, the voltage value of the first sampling voltage signal Vsen1 output by the sampling unit 10 and the voltage value of the second sampling voltage signal Vsen2 output by the isolation unit 20 to the conversion module 50 are equal or approximately equal, that is, the total voltage drop of M21, M22 and M23 in the isolation unit 20 is very small or even zero, which can be ignored. When M11, M12, M13, M21, M22 and M23 are turned off at the same time, the sampling unit 10 cannot output the first sampling voltage signal Vsen1 to the isolation unit 20, and the isolation unit 20 cannot output the second sampling voltage signal Vsen2 to the conversion module 50. At this time, the voltage value of the input voltage signal Vin of the sampling unit 10 is much larger than the voltage value of the second sampling voltage signal Vsen2 output by the isolation unit 20 to the conversion module 50, which can trigger the pull-up unit 30 to be turned on and output a preset voltage to the conversion module 50, so as to ensure that the conversion module 50 has a continuous input voltage, and the current mirror is always in the saturation region, thereby improving the establishment speed and accuracy of the second sampling voltage.

[0054] It should be noted that M21, M22 and M23 are all N-type MOS tubes, and selecting N-type MOS tubes can make the drain of M23 electrically connected with the pull-up unit 30. When the pull-up unit 30 is triggered, the drain of M23 receives the preset voltage output by the pull-up unit 30. When the preset voltage output by the pull-up unit 30 is a high voltage signal, the drain and the gate and the source of M23 can withstand high voltage, which can prevent M23 from being damaged when the pull-up unit 30 outputs a preset high voltage, and improves the reliability of the sampling circuit 01.

[0055] In an embodiment of the present application, the source of the dth second switch tube is electrically connected with the drain of the (d+1)th second switch tube, where d is a positive integer, and 1≤d

[0056] Specifically, the source of the dth second switch and the drain of the (d+1)th second switch are electrically connected, realizing that all the second switches in the isolation unit 20 are connected in series. If d = 1, the source of the dth second switch is electrically connected with the source of the ath first switch, and serves as an input terminal of the isolation unit 20, for receiving the first sampling voltage signal Vsen1 output by the sampling unit 10; if d > 1, the source of the dth second switch is electrically connected with the drain of the (d-1)th second switch, for receiving the voltage signal output by the drain of the (d-1)th second switch, and the source of the (d+1)th second switch is electrically connected with the drain of the dth second switch, for receiving the voltage signal output by the drain of the dth second switch.

[0057] For example, when the value of d is 2, the source of the second second switch M22 is electrically connected with the drain of the first second switch M21, for receiving the voltage signal output by the drain of the first second switch M21, and the source of the third second switch M23 is electrically connected with the drain of the second second switch M22, for receiving the voltage signal output by the drain of the second second switch M22.

[0058] It should be noted that, as shown in Figure 3 the value of c is 3 and the value of d is 2, at this time, the source and the drain of M22 can be interchanged, i.e., the drain of M22 is electrically connected with the drain of M21, for receiving the voltage signal output by the drain of M21, and the source of M23 is electrically connected with the source of M22, for receiving the voltage signal output by the source of M22.

[0059] In an embodiment of the present application, the pull-up unit 30 includes e third switches connected in series, the source of the first third switch is electrically connected with the input power supply 60, the drain of the e-th third switch is electrically connected with the conversion module 50, the gate of each third switch is electrically connected with the drain of the third switch, wherein e is a positive integer.

[0060] Specifically, the switch tubes in the pull-up unit 30 are defined as third switch tubes, and each third switch tube is connected in series. The source of the first third switch tube is electrically connected with the input power supply 60 and serves as the input end of the pull-up unit 30, for receiving the input voltage signal Vin output by the input power supply 60. The drain of the e-th third switch tube serves as the output end of the pull-up unit 30, for outputting the preset voltage to the conversion module 50. Meanwhile, the gate of each third switch tube is connected with the drain thereof, and each third switch tube is equivalent to a diode, and all the third switch tubes in series are equivalent to all the diodes in series. When all the first switch tubes and all the second switch tubes are turned off at the same time, the sampling unit 10 cannot output the first sampling voltage signal Vsen1 to the isolation unit 20, and the isolation unit 20 cannot output the second sampling voltage signal Vsen2 to the conversion module 50. At this time, the voltage value of the input voltage signal Vin of the sampling unit 10 is far greater than the voltage value of the second sampling voltage signal Vsen2 output by the isolation unit 20 to the conversion module 50, and the pull-up unit 30 can be turned on, i.e., the difference between the voltage value of the input voltage signal Vin of the sampling unit 10 and the voltage value of the second sampling voltage signal Vsen2 is greater than the turn-on voltage of all the third switch tubes in the pull-up unit 30, at this time, all the third switch tubes are turned on, and the drain of the e-th third switch tube outputs the preset voltage to the conversion module 50, so as to ensure that the conversion module 50 has a continuous input voltage, thereby improving the establishment speed and accuracy of the second sampling voltage.

[0061] It should be noted that the designer can select a proper number of third switch tubes according to the actual situation, and can select a proper number of MOS tubes as the third switch tubes to meet the actual needs of the pull-up unit 30. Meanwhile, the designer can also select the type of the third switch tube according to the actual needs, for example, selecting a P-type MOS tube to meet the needs of the pull-up unit 30 to output the preset voltage to the conversion module 50.

[0062] For example, Figure 3As shown, the pull-up unit 30 includes two third switch tubes connected in series, and M31 and M32 are both third switch tubes. Among them, M31 is the first third switch tube, the source of M31 is electrically connected with the input power supply 60 and serves as the input end of the pull-up unit 30, and is used to receive the input voltage signal Vin output by the input power supply 60. M32 is the second third switch tube, the drain of M32 serves as the output end of the pull-up unit 30 and outputs the preset voltage to the conversion module 50. At the same time, the gate of M31 is electrically connected with the drain of M31, the gate of M32 is electrically connected with the drain of M32, M31 and M32 are equivalent to diodes, and M31 and M32 in series are equivalent to two diodes in series. When M11, M12, M13, M21, M22 and M23 are all turned off, the sampling unit 10 cannot output the first sampling voltage signal Vsen1 to the isolation unit 20, and the isolation unit 20 cannot output the second sampling voltage signal Vsen2 to the conversion module 50. At this time, the voltage value of the input voltage signal Vin of the sampling unit 10 is much larger than the voltage value of the second sampling voltage signal Vsen2 output by the isolation unit 20 to the conversion module 50, and can trigger the pull-up unit 30 to turn on, that is, the difference between the voltage value of the input voltage signal Vin of the sampling unit 10 and the voltage value of the second sampling voltage signal Vsen2 is greater than the sum of the turn-on voltages of M31 and M32 in the pull-up unit 30, at this time, M31 and M32 are turned on, the drain of M32 outputs the preset voltage to the conversion module 50, and ensures that the conversion module 50 has a continuous input voltage, thereby improving the establishment speed and accuracy of the second sampling voltage.

[0063] It should be noted that M31 and M32 are both P-type MOS tubes, the gate of the P-type MOS tube is electrically connected with the drain, which is equivalent to a diode conducting from top to bottom, the anode of the diode is electrically connected with the input power supply 60 and serves as the input end of the pull-up unit 30, and is used to receive the input voltage signal Vin output by the input power supply 60. The cathode of the diode serves as the output end of the pull-up unit 30 and outputs the preset voltage to the conversion module 50. The reason for not directly using diodes in series is that when the pull-up unit 30 receives the input voltage signal Vin output by the input power supply 60 as a high-voltage signal, the diode may be damaged due to its poor high-voltage resistance, and the P-type MOS tube has strong high-voltage resistance and can receive the high-voltage signal output by the input power supply 60, thereby improving the reliability of the sampling circuit 01.

[0064] In an embodiment of the present application, the drain of the fth third switch tube is electrically connected with the source of the f+1th third switch tube, where f is a positive integer and 1≤f

[0065] Specifically, the drain of the fth third switch is connected to the source of the f+1th third switch, thereby connecting all third switches in the pull-up unit 30 in series. If f=1, the source of the fth third switch is electrically connected to the input power supply 60 and serves as the input of the pull-up unit 30, receiving the input voltage signal Vin output by the input power supply 60. If f>1, the source of the fth third switch is electrically connected to the drain of the f-1th third switch, receiving the voltage signal output by the drain of the f-1th third switch. The source of the f+1th third switch is electrically connected to the drain of the fth third switch, receiving the voltage signal output by the drain of the f-1th third switch.

[0066] For example, Figure 3 As shown, the value of f is 2. At this time, the source of the second third switch transistor M32 is electrically connected to the drain of the first third switch transistor M31, and is configured to receive the voltage signal output by the drain of the first third switch transistor M31. When the difference between the voltage value of the input voltage signal Vin and the voltage value of the second sampled voltage signal Vsen2 is greater than the sum of the conduction voltages of M31 and M32 in the pull-up unit 30 (i.e., equivalent to the conduction voltage of two diodes connected in series, 1.4V), M31 and M32 are turned on, and the drain of M32 outputs a preset voltage to the conversion module 50, ensuring that the conversion module 50 has a continuous input voltage, thereby improving the speed and accuracy of establishing the second sampled voltage.

[0067] The present application also discloses a DC-DC converter, including the above-mentioned sampling circuit 01. The DC-DC converter adopts the above-mentioned sampling circuit 01 to ensure that the conversion module 50 has a continuous input voltage signal, thereby improving the establishment speed and accuracy of the second sampling voltage.

[0068] The above-described 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. 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 various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A sampling circuit, applied to a DC-DC converter, the DC-DC converter comprising a comparison module and a conversion module, the conversion module being configured to convert an error-amplified voltage signal output by the DC-DC converter into a sampled current signal, the comparison module being configured to compare a first sampled voltage signal with a switch node voltage signal and output a modulation signal, the DC-DC converter being configured to adjust the switch node voltage signal based on the modulation signal and an input voltage signal output by an input power supply, characterized in that: The sampling circuit comprises: a sampling unit, connected in series between the input power supply and the comparison module, and configured to output the first sampling voltage signal to the comparison module according to the modulation signal and the input voltage signal; an isolation unit, connected in series between the sampling unit and the conversion module, and configured to output a second sampling voltage signal to the conversion module according to the first sampling voltage signal and the modulation signal; a pull-up unit, connected in series between the input power supply and the conversion module, and configured to output a preset voltage to the conversion module according to the input voltage signal when the sampling unit does not output the first sampling voltage signal.

2. The sampling circuit of claim 1, wherein, The sampling unit comprises a first switch tube connected in series, a drain electrode of a first first switch tube is electrically connected with the input power supply, a source electrode of an a-th first switch tube is electrically connected with the comparison module and the isolation unit respectively, and a gate electrode of all the first switch tubes receives the modulation signal, wherein a is a positive integer.

3. The sampling circuit of claim 2, wherein, A source electrode of a b-th first switch tube is electrically connected with a drain electrode of a b+1-th first switch tube, wherein b is a positive integer and 1≤b 4. The sampling circuit of claim 2, wherein, The isolation unit comprises a second switch tube connected in series, a source electrode of a first second switch tube is electrically connected with a source electrode of the a-th first switch tube, a drain electrode of a c-th second switch tube is electrically connected with the conversion module, and a gate electrode of all the second switch tubes receives the modulation signal, wherein c is a positive integer.

5. The sampling circuit of claim 4, wherein, A source electrode of a d-th second switch tube is electrically connected with a drain electrode of a d+1-th second switch tube, wherein d is a positive integer and 1≤d 6. The sampling circuit according to claim 4, wherein all the first switch tubes and all the second switch tubes are N-type MOS tubes.

7. The sampling circuit of any one of claims 1 to 6, wherein, The pull-up unit comprises a third switch tube connected in series, a source electrode of a first third switch tube is electrically connected with the input power supply, a drain electrode of an e-th third switch tube is electrically connected with the conversion module, a gate electrode of each third switch tube is electrically connected with a respective drain electrode, and e is a positive integer.

8. The sampling circuit of claim 7, wherein, A drain electrode of a f-th third switch tube is electrically connected with a source electrode of a f+1-th third switch tube, wherein f is a positive integer and 1≤f 9. The sampling circuit of claim 7, wherein, All the third switch tubes are P-type MOS tubes.

10. A DC-DC converter, characterized by The sampling circuit comprises the sampling circuit according to any one of claims 1-9.

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