Power conversion circuit, current sampling method and electronic equipment

Abstract

The invention provides a power conversion circuit, a current sampling method and electronic equipment, the power conversion circuit comprises a power level circuit, a current sampling circuit and a driving control circuit, and the power level circuit comprises a low-voltage side power tube and at least two high-voltage side power tubes. According to the power level circuit, the high-voltage side power tubes in a traditional power level circuit are grouped, the power level circuit comprises the multiple high-voltage side power tubes which are respectively driven by the driving control circuit, the current sampling circuit carries out current sampling on the target high-voltage side power tube at the moment, the sampling proportion can be reduced, and the sampling efficiency is improved. Therefore, the size difference between the sampling device and the target high-voltage side power tube is reduced, and the current sampling precision is improved; and the to-be-sampled target high-voltage side power tube is subjected to time-delay driving, so that a large-current peak is avoided, and improvement of the accuracy of a sampled signal and improvement of the reliability of the whole circuit are facilitated.

Description

Technical Field

[0001] The present application relates to the field of circuit technology, and in particular to a power conversion circuit, a current sampling method and an electronic device. Background Art

[0002] In analog integrated circuit design, DC-DC circuits require real-time monitoring of inductor current due to their different operating modes and different application requirements, in order to determine whether the inductor current reaches the preset peak current limit or exceeds the rated overcurrent capability of the circuit, thereby effectively controlling the power stage circuit in real time. Usually, the inductor and silicon-based circuit devices are not made on the same chip wafer, so it is difficult to directly sample the inductor current. The current flowing through the power switch tube when it is turned on is the inductor current, so the current waveform of the inductor current rising stage can be indirectly obtained by sampling the current value of the power switch tube.

[0003] The current flowing through the power tube in the on state is the inductor current. The average value of the inductor current is equal to the output load current. The load current is affected by the system application and can reach the ampere level. Direct sampling of this ampere-level current requires a larger circuit and will increase the on-resistance of the power tube, resulting in unnecessary power loss. On this basis, a scheme of using a sampling tube to sample the current of the power tube has emerged. By reasonably setting the sampling tube, the function of sampling the power tube current by detecting a small current can be realized. However, there is a size difference between the sampling tube and the power tube, and their sizes cannot be completely matched, resulting in the sampling tube current and the power tube current not being completely the required proportional relationship, and the larger the size difference between the two, the worse the matching. In addition, there will be a large overshoot current in the power stage circuit when the power tube is turned on, and if the response speed of the current sampling circuit is slow, it may cause sampling signal errors, causing the drive control signal to flip incorrectly, thereby affecting the normal operation of the entire system. Summary of the invention

[0004] The main purpose of the present application is to provide a power conversion circuit, a current sampling method and an electronic device, which can at least solve the problem of low current sampling accuracy in the related art.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a power conversion circuit, including: a power stage circuit, a current sampling circuit and a drive control circuit; the power stage circuit includes a low-voltage side power tube and at least two high-voltage side power tubes, the high-voltage side power tube is electrically connected to the low-voltage side power tube and the drive control circuit respectively, the current sampling circuit is electrically connected to the target high-voltage side power tube, and the drive control circuit is also electrically connected to the low-voltage side power tube; the drive control circuit is configured to: output a first conduction control signal to the remaining high-voltage side power tubes, and output a second conduction control signal to the target high-voltage side power tube after a delay of a preset time; the current sampling circuit is configured to: perform current sampling on the target high-voltage side power tube to obtain a voltage signal; wherein the voltage signal is used to reflect the current information of the target high-voltage side power tube.

[0006] The second aspect of the present application provides a current sampling method, which is applied to the power conversion circuit as described in the first aspect of the present application. The current sampling method includes: the driving control circuit outputs a first conduction control signal to the remaining high-voltage side power tubes, and outputs a second conduction control signal to the target high-voltage side power tube after a preset delay; the current sampling circuit samples the current of the target high-voltage side power tube to obtain a voltage signal; wherein the voltage signal is used to reflect the current information of the target high-voltage side power tube.

[0007] A third aspect of the present application provides an electronic device, comprising the power conversion circuit as described in the first aspect of the present application.

[0008] From the above description, it can be seen that the present application groups a high-voltage side power tube in a traditional power stage circuit so that the power stage circuit includes multiple high-voltage side power tubes, each of which matches each other and is driven separately by a drive control circuit; at this time, the current sampling circuit reduces the sampling ratio by sampling the current of one of the power tubes, thereby reducing the size difference between the sampling device and the sampled high-voltage side power tube, making the two easier to match, thereby improving the current sampling accuracy. In addition, by delaying the driving of the target high-voltage side power tube to be sampled, it can be ensured that there is no current spike on the target high-voltage side power tube, which is beneficial to improving the accuracy of the sampling signal and improving the reliability of the overall circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0010] Figure 1It is a circuit schematic diagram of a power conversion circuit in the related art;

[0011] Figure 2 is a circuit schematic diagram of a power tube parasitic effect provided by an embodiment of the present application;

[0012] Figure 3 is a schematic diagram of the structure of a power conversion circuit provided in an embodiment of the present application;

[0013] Figure 4 is a circuit schematic diagram of a power conversion circuit provided in an embodiment of the present application;

[0014] Figure 5 It is a flow chart of a current sampling method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0015] In order to make the purpose, features, and advantages of the invention of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0016] In the related art, in order to realize the function of sampling the power tube current by detecting a small current, a sampling tube can be used to sample the current of the power tube, for example Figure 1 As shown in the power conversion circuit in the figure, the sampling tube and the power tube are of the same model type and the ratio of width to length is If the source, gate, and drain of the two devices are equal, the ratio of the current flowing through them is equal to the size ratio 1:m. However, there is a size difference between the sampling tube and the power tube, and their sizes cannot be completely matched, resulting in the sampling tube current and the power tube current not being completely 1:m. For example, according to the MOS tube current I D formula:

[0017]

[0018] Among them, μ n is the electron mobility, C ox is the gate oxide capacitance per unit area, μ n C ox It is a process constant and is only related to the process used; is the aspect ratio of the device; V GS is the gate-source voltage, V TH is the threshold voltage, V DS is the drain-source voltage.

[0019] It can be seen that for the sampling tube MP1, the current I D1 for:

[0020]

[0021] For the sampled tube MP0, the current I D2 for:

[0022]

[0023] Therefore, the current ratio of the sampling tube MP1 to the sampled tube MP0 is:

[0024]

[0025] From the formula, we can get: The sampling current ratio is affected by V GS Voltage, V DS Voltage. However, due to the influence of routing parasitics, such as Figure 2 As shown, there will be parasitic resistance and parasitic inductance at the port of the MOS tube. When there is an input resistance R G This resistor will affect its V GS voltage, resulting in V GS =V GS ′-R G ·mI G (V GS ′ is the gate-source voltage corresponding to the absence of parasitic effects), thus affecting the drain current I D When there is a parasitic resistance R at the source end of the MOS tube S When V GS and V DS will have an impact, resulting in V GS =V GS ′-R S mI2,V DS =V DS ′-R D ·mI D -R S ·mI2(V DS ′ is the corresponding drain-source voltage when there is no parasitic effect), resulting in the parasitic effect of the source end to cope with the leakage current I D The influence of is exponential. And when the load is larger, the current flowing through the source end parasitic resistance is larger, and the voltage on the parasitic resistance is larger, thus affecting the current sampling accuracy.

[0026] In addition, the current sampling circuit usually samples the high-side power tube and only samples when the sampled power tube is turned on. After the power tube is turned on, due to non-ideal effects such as the reverse recovery current of the body diode (synchronous rectification mode) or the freewheeling diode (asynchronous rectification mode) of the low-side power tube, a large current overshoot will be generated at the moment the power tube is turned on, which may cause the PWM (pulse width modulation) comparator to be triggered incorrectly, resulting in sampling signal errors. In addition, the I D The current will quickly rise from 0 to the inductor current I L , which places requirements on the start-up speed and sampling speed of the sampling circuit. When the start-up signal of the power tube arrives, if the response speed of the current sampling circuit is slow and the internal bias is not fully established, it may also cause errors in the early sampling signal. If the sampling peak is large enough to exceed the peak current and the PWM comparator is mistakenly triggered, it will cause the signal to flip incorrectly, affecting the normal operation of the entire system. To this end, the commonly used solution is to add an additional blanking circuit to shield the period before sampling, but the design of the blanking time needs to ensure that the shielding time can cover the current peak time, which is difficult to accurately grasp, and adding additional circuits will also increase the complexity of the circuit. To this end, an embodiment of the present application provides a power conversion circuit.

[0027] like Figure 3 The figure is a schematic diagram of the structure of a power conversion circuit provided by an embodiment of the present application, the power conversion circuit includes: a power stage circuit 100, a current sampling circuit 200 and a drive control circuit 300; the power stage circuit 100 includes at least two high-voltage side power tubes 110 and a low-voltage side power tube 120, the high-voltage side power tube 110 is electrically connected to the low-voltage side power tube 120 and the drive control circuit 300 respectively, the current sampling circuit 200 is electrically connected to the target high-voltage side power tube, and the drive control circuit 300 is also electrically connected to the low-voltage side power tube 120, wherein:

[0028] The drive control circuit 300 is configured to: output a first conduction control signal to the remaining high-voltage side power tubes, and output a second conduction control signal to the target high-voltage side power tube after a preset delay; the current sampling circuit 200 is configured to: perform current sampling on the target high-voltage side power tube to obtain a voltage signal; wherein the voltage signal is used to reflect the current information of the target high-voltage side power tube.

[0029] Specifically, in the present embodiment, the power conversion circuit may be a DC-DC conversion circuit, and the power stage circuit 100 may be a full-bridge driven circuit or a half-bridge driven circuit. The present embodiment is described by taking a half-bridge driven circuit as an example. When the power stage circuit 100 is a half-bridge circuit, the power stage circuit 100 includes a low-voltage side power tube and at least two high-voltage side power tubes, and the multiple high-voltage side power tubes are connected in parallel. That is, in the present embodiment, a power tube with a relatively large width-to-length ratio is divided into multiple power tubes, each of which is matched with each other and driven by the drive control circuit 300 respectively. The final driving voltage of each high-voltage side power tube is the same, that is, the grouping will not cause the difference in conduction characteristics between the high-voltage side power tubes, and since no resistor or other circuit structure is connected in series on the power tube, the final conduction circuit of the power tube will not be affected. At this time, the current sampling circuit 200 performs current sampling on one of the power tubes, so that the sampling ratio can be reduced, thereby reducing the size difference between the sampling tube and the sampled power tube, making the two easier to match, thereby reducing V GS 、V DS The error caused by the difference can be reduced to improve the current sampling accuracy. In addition, by delaying the driving of the target high-voltage side power tube to be sampled to avoid large current spikes, it can ensure that there is no current spike on the target high-voltage side power tube, thereby improving the accuracy of the sampling signal, and there is no need to add a blanking circuit, simplifying the circuit structure.

[0030] like Figure 4 FIG. 1 is a schematic diagram of a power conversion circuit according to an embodiment of the present application. Figure 4 The power stage circuit 100 includes a first high-voltage side power tube MP2 and a second high-voltage side power tube MP0; the source electrodes of the first high-voltage side power tube MP2 and the second high-voltage side power tube MP0 are both electrically connected to the power supply, and the drain electrodes of the first high-voltage side power tube MP2 and the second high-voltage side power tube MP0 are both electrically connected to the low-voltage side power tube 120 (i.e. Figure 4 The drain of the first high-voltage side power tube MP2, the second high-voltage side power tube MP0 and the low-voltage side power tube MN0 are all electrically connected to the drive control circuit 300, and the source of the low-voltage side power tube MN0 is grounded.

[0031] Specifically, the ratio of the width to length of the first high-voltage side power tube MP2 and the second high-voltage side power tube MP0 is m:n; wherein n <m。

[0032] Further, when the power stage circuit 100 includes N (N>2) high-voltage side power tubes, the sources of the N high-voltage side power tubes are all electrically connected to the power supply, the drains of the N high-voltage side power tubes are all electrically connected to the drain of the low-voltage side power tube, and the gates of the N high-voltage side power tubes are all electrically connected to the drive control circuit.

[0033] For further information, see Figure 4, the current sampling circuit 200 includes a first sampling tube MP3 and a second sampling tube MP1; the source of the first sampling tube MP3 is electrically connected to the source of the second high-voltage side power tube MP0, the gate of the first sampling tube MP3 is grounded, the drain of the first sampling tube MP3 is electrically connected to the control loop and the source of the second sampling tube MP1 respectively, the drain of the second sampling tube MP1 is electrically connected to the drain of the second high-voltage side power tube MP0, and the gate of the second sampling tube MP1 is electrically connected to the drive control circuit 300; the current sampling circuit 200 is configured to: perform current sampling on the second high-voltage side power tube MP0 to obtain a voltage signal. When the power stage circuit 100 includes N high-voltage side power tubes, the current sampling circuit can sample the current of the high-voltage side power tube with the smallest width-to-length ratio.

[0034] Specifically, when the first sampling tube MP3 and the second sampling tube MP1 have the same size, the ratio of the sum of the width-to-length ratios of the first sampling tube MP3 and the second sampling tube MP1 to the width-to-length ratio of the second high-voltage side power tube MP0 is 2:n; wherein n>2.

[0035] In this embodiment, the high-voltage side power tube is divided into two high-voltage side power tubes MP0 and MP2 with a width-to-length ratio of n:m (n is less than m). The current sampling circuit 200 uses two sampling tubes of the same model. The two sampling tubes have the same size and the same model as the high-voltage side power tube. The width-to-length ratio of the first sampling tube MP3 to the second sampling tube MP1 can be 1:1. If the ratio of the sum of the width-to-length ratios of the two sampling tubes to the width-to-length ratio of the sampled tube (the second high-voltage side power tube MP0 in this embodiment) is 2:n (n is greater than 2), the ratio of the current flowing through the two sampling tubes to the current flowing through the second high-voltage side power tube MP0 is 1:n. By selecting the second high-voltage side power tube MP0 for current sampling, the current sampling ratio will change from 1:(m+n) to 1:n, thereby reducing the size difference between the sampling tube and the sampled power tube, making it easier to match the two to reduce the V GS 、V DS The error caused by the difference can improve the current sampling accuracy.

[0036] However, if the high-voltage side power tubes are grouped, there will also be the problem of false triggering of the PWM comparator due to the presence of a large current spike in the early stage of the power tube being turned on, and the grouped power tubes are driven separately, making it difficult to turn on completely at the same time, resulting in a large current preferentially passing through the power tube that is turned on first, aggravating the impact of the current spike. Therefore, on the basis of grouping the high-voltage side power tubes, it is necessary to adjust the turn-on speed of each high-voltage side power tube. In this embodiment, the drive control circuit 300 preferentially drives the power tubes other than the target high-voltage side power tube, such as MP2, to turn on, and the sampled target high-voltage side power tube, such as MP0, is turned on later. Among them, the delayed drive can be realized by a circuit with a delay effect such as an RC delay circuit; by adjusting the output of the drive control circuit 300, the turn-on speed of the high-voltage side power tube 110 is adjusted. When the turn-on signal arrives, the large current spike mainly passes through the first high-voltage side power tube MP2 in the on state. Due to the effect of the delay circuit, the V GS0 Existence RC The delay when V GS0 After reaching the threshold voltage, it slowly turns on and the current slowly rises. After 5 times t RC After the time constant, V GS0 Already reached 99.3%*V GS2 At this time, the large current spike has passed, and there is no large current spike on the second high-voltage side power tube MP0 being sampled. Current sampling at this time can avoid spikes in the sampling signal and ensure the accuracy of the sampling signal.

[0037] In addition, in order to ensure the final on-resistance of the power tube, it is necessary to set 5t RC <T on , T on is the conduction time of the power tube; and in order to ensure that the circuit can skip the current peak time, t RC Need to be greater than the current peak time t spike , from which we can get t RC scope.

[0038] In addition, the method of driving the high-voltage side power tubes in groups can slow down the instantaneous voltage dv / dt and instantaneous current di / dt of the power tubes during the driving start-up process, thereby effectively improving the EMI electromagnetic interference effect caused by turning on and off the power stage circuit 100, and reducing the crosstalk overshoot caused by dv / dt and di / dt through circuit parasitics, which can effectively enhance the reliability of the circuit.

[0039] Further, see Figure 4The power conversion circuit also includes a control unit, which is electrically connected to the current sampling circuit 200 and the drive control circuit 300 respectively; the control unit is configured to: if it is determined according to the voltage signal that the current of the target high-voltage side power tube reaches a preset current threshold, a control signal is generated; wherein the control signal is used to instruct the drive control circuit 300 to output a shutdown drive signal to the high-voltage side power tube 110.

[0040] Specifically, in this embodiment, the current sampling circuit 200 performs current sampling on the target high-voltage side power tube through two sampling tubes, and obtains a voltage signal for reflecting the current signal. Figure 4 Taking the power conversion circuit in FIG. 1 as an example, when the second sampling tube MP1, the first high-voltage side power tube MP2, and the second high-voltage side power tube MP0 are all turned on, the sampling voltage V CS for:

[0041]

[0042] Among them, V DD is the supply voltage, R dson_MP3 is the on-resistance of the first sampling tube MP3, I CS is the current flowing through the first sampling tube MP3, R dson_MP0 is the on-resistance of the second high-voltage side power tube MP0, I P0 It is the current flowing through the second high-voltage side power tube MP0.

[0043] According to the above formula, I CS with I P0 The relationship is:

[0044]

[0045] From the above formula, we can see that V CS It reflects the current information of the power tube. After obtaining the required sampling voltage, the sampling voltage can be amplified and then transmitted to the control unit, so that the control unit detects the sampling voltage; when the control unit detects that the current of the target high-voltage side power tube reaches the preset current threshold, it will generate a control signal and output it to the drive control circuit 300, so that the drive control circuit 300 outputs a shutdown control signal to all high-voltage side power tubes 110, so that they are shut down until the next PWM cycle.

[0046] The power conversion circuit provided in the embodiment of the present application groups high-voltage side power tubes with a relatively large width-to-length ratio, that is, the power stage circuit includes at least two high-voltage side power tubes, each of which is matched with each other and driven by a driving control circuit respectively. At this time, the current sampling circuit samples the current of one of the power tubes, so that the sampling ratio can be reduced, thereby reducing the size difference between the sampling tube and the sampled power tube, making it easier to match the two, thereby reducing V GS 、V DS The error caused by the difference can be reduced to improve the current sampling accuracy. In addition, by delaying the driving of the target high-voltage side power tube to be sampled to avoid large current spikes, it can ensure that there is no current spike on the target high-voltage side power tube, thereby improving the accuracy of the sampling signal, and there is no need to add a blanking circuit, simplifying the circuit structure.

[0047] The present application also provides a current sampling method, which is applied to the above power conversion circuit. Figure 5 The current sampling method shown in FIG. 1 is a flow chart of the current sampling method, the method comprising:

[0048] Step 501: The driving control circuit outputs a first conduction control signal to the remaining high-voltage side power tubes, and outputs a second conduction control signal to the target high-voltage side power tube after a delay of a preset time length;

[0049] Step 502: The current sampling circuit samples the current of the target high-voltage side power tube to obtain a voltage signal.

[0050] Specifically, in this embodiment, in order to avoid the large current spike existing in the early stage of the high-voltage side power tube being turned on, which causes the sampling current to exceed the normal value, thereby causing the PWM comparator to be falsely triggered, the drive control circuit will time-share the target high-voltage side power tube and the remaining high-voltage side power tubes, wherein the drive control circuit will give priority to driving the remaining power tubes to turn on, and then drive the target high-voltage side power tube to turn on after a preset delay time. In this way, when the conduction control signal output by the drive control circuit arrives, the large current spike mainly passes through the remaining high-voltage side power tubes in the on state, and after the preset delay time, the conduction control signal is output to the target high-voltage side power tube. At this time, the large current spike has passed, and there is no large current spike on the second high-voltage side power tube being sampled. At this time, current sampling can avoid spikes in the sampling signal and ensure the accuracy of the sampling signal. Among them, in order to ensure the final on-resistance of the power tube, it is necessary to set 5t RC <T on , T on is the conduction time of the power tube; and in order to ensure that the circuit can skip the current peak time, t RC Need to be greater than the current peak time t spike , from which we can get The delay time tRC At the same time, the current sampling circuit in this embodiment performs current sampling on the grouped high-voltage side power tubes, so that the size difference between the sampling tube and the sampled tube in the sampling circuit is reduced, thereby improving the current sampling accuracy.

[0051] Furthermore, in some implementations of this embodiment, the current sampling method also includes: the driving control circuit outputs a second conduction control signal to the second sampling tube of the current sampling circuit; wherein, when the second sampling tube enters the conduction state, the current sampling circuit performs current sampling on the target high-voltage side power tube.

[0052] Furthermore, in some implementations of the present embodiment, the current sampling method also includes: if the control unit determines that the current of the target high-voltage side power tube reaches a preset current threshold based on the voltage signal, a control signal is generated; and the drive control circuit outputs a shutdown drive signal to all high-voltage side power tubes based on the control signal.

[0053] Specifically, in this embodiment, the second conduction control signal output by the drive control circuit is transmitted to the current sampling circuit and the target high-voltage side power tube respectively, so as to perform current sampling when the target high-voltage side power tube is turned on. The current sampling circuit samples the current of the target high-voltage side power tube through two sampling tubes, and obtains a voltage signal for reflecting the current signal. The voltage signal can be amplified and processed before being transmitted to the control unit, so that the control unit detects the sampled voltage; when the control unit detects that the current of the target high-voltage side power tube reaches the preset current threshold, a control signal is generated and output to the drive control circuit, so that the drive control circuit outputs a shutdown control signal to all high-voltage side power tubes, so that they are turned off until the next PWM cycle.

[0054] The embodiment of the present application also provides an electronic device, which includes the above-mentioned power conversion circuit. The electronic device can be a portable electronic device such as a mobile phone, a tablet computer, a laptop computer, a desktop computer, an intelligent learning machine, and an intelligent wearable device.

[0055] It should be noted that the various embodiments in the present application are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0056] It should also be noted that, in the content of the present application, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" can expressly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements that are not clearly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "include one..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

[0057] The above description of the disclosed embodiments enables professionals and technicians in the field to implement or use the present application. Various modifications to these embodiments will be apparent to professionals and technicians in the field, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown in the present application, but will conform to the widest range consistent with the principles and novel features disclosed in the present application.

Claims

1. A power conversion circuit, characterized in that: include: Power stage circuit, current sampling circuit and drive control circuit; The power stage circuit includes a low-voltage side power tube and at least two high-voltage side power tubes, the high-voltage side power tubes are electrically connected to the low-voltage side power tube and the drive control circuit respectively, the current sampling circuit is electrically connected to the target high-voltage side power tube, and the drive control circuit is also electrically connected to the low-voltage side power tube; The drive control circuit is configured to: output a first conduction control signal to the remaining high-voltage side power tubes, and output a second conduction control signal to the target high-voltage side power tube after a delay of a preset time length; The current sampling circuit is configured to: perform current sampling on the target high-voltage side power tube to obtain a voltage signal; wherein the voltage signal is used to reflect the current information of the target high-voltage side power tube.

2. The power conversion circuit according to claim 1, characterized in that: The power stage circuit includes a first high-voltage side power tube and a second high-voltage side power tube; The sources of the first high-voltage side power tube and the second high-voltage side power tube are electrically connected to a power supply, the drains of the first high-voltage side power tube and the second high-voltage side power tube are electrically connected to the drain of the low-voltage side power tube, the gates of the first high-voltage side power tube, the second high-voltage side power tube and the low-voltage side power tube are electrically connected to the drive control circuit, and the source of the low-voltage side power tube is grounded.

3. The power conversion circuit according to claim 2, characterized in that: The ratio of the width to length of the first high-voltage side power tube and the second high-voltage side power tube is m:n; wherein n <m。 4. The power conversion circuit according to claim 2, characterized in that: The current sampling circuit includes a first sampling tube and a second sampling tube; The source of the first sampling tube is electrically connected to the source of the second high-voltage side power tube, the gate of the first sampling tube is grounded, the drain of the first sampling tube is electrically connected to the control loop and the source of the second sampling tube respectively, the drain of the second sampling tube is electrically connected to the drain of the second high-voltage side power tube, and the gate of the second sampling tube is electrically connected to the drive control circuit; The current sampling circuit is configured to: perform current sampling on the second high-voltage side power tube to obtain a voltage signal.

5. The power conversion circuit according to claim 4, characterized in that: When the first sampling tube and the second sampling tube have the same size, the ratio of the sum of the width-to-length ratios of the first sampling tube and the second sampling tube to the width-to-length ratio of the second high-voltage side power tube is 2:n; wherein n>2.

6. The power conversion circuit according to claim 1, characterized in that: It also includes a control unit, which is electrically connected to the current sampling circuit and the drive control circuit respectively; The control unit is configured to generate a control signal if it is determined according to the voltage signal that the current of the target high-voltage side power tube reaches a preset current threshold; wherein the control signal is used to instruct the drive control circuit to output a shutdown drive signal to the high-voltage side power tube.

7. A current sampling method, characterized in that: Applied to the power conversion circuit according to any one of claims 1 to 6, the current sampling method comprises: The drive control circuit outputs a first conduction control signal to the remaining high-voltage side power tubes, and outputs a second conduction control signal to the target high-voltage side power tube after a delay of a preset time length; The current sampling circuit samples the current of the target high-voltage side power tube to obtain a voltage signal; wherein the voltage signal is used to reflect the current information of the target high-voltage side power tube.

8. The current sampling method according to claim 7, characterized in that: Also includes: The drive control circuit outputs the second conduction control signal to the second sampling tube of the current sampling circuit; wherein, when the second sampling tube enters the conduction state, the current sampling circuit performs current sampling on the target high-voltage side power tube.

9. The current sampling method according to claim 7, characterized in that: Also includes: If the control unit determines according to the voltage signal that the current of the target high-voltage side power tube reaches a preset current threshold, a control signal is generated; The drive control circuit outputs a shut-off drive signal to all high-voltage side power tubes according to the control signal.

10. An electronic device, characterized in that: The invention comprises a power conversion circuit as claimed in any one of claims 1 to 6.

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