Foreign matter detection circuit and chip

Abstract

The foreign matter detection circuit comprises a first half bridge, a second half bridge, an inductor and a first capacitor which are connected in series, a fifth switch tube and an energy consumption element which are connected in series and connected between a voltage supply end and a first common connection point formed by the inductor and the first capacitor; the control module is respectively connected with the controlled ends of the switching tubes, controls the fifth switching tube to be switched on for a first preset time period and then switched off, and is matched with the switching tubes to actively establish initial voltage for the first common contact through the voltage supply end; and the detection module is connected with the first common contact, and after the first switch tube is conducted for a first preset time period, the control module controls the on-off state of each switch tube, so that the first common contact freely oscillates, and whether foreign matters exist or not is detected. The first preset time period for establishing the initial voltage is extremely small, a detection circuit for judging whether the first common contact reaches the initial voltage does not need to be specially arranged, the design difficulty is reduced, the chip area is reduced, and the situation of false detection is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a foreign body detection circuit and a chip. Background Art

[0002] In the current foreign object detection scheme for wireless charging, the following is usually detected Figure 1 The oscillating voltage waveform at the node M shown in FIG. 1 is used to determine whether there is a foreign object. Specifically, when performing foreign object detection, the following is generally controlled first: Figure 1 The power tube Q1 and the power tube Q4 shown in the figure are turned on for a period of time and then turned off, and then the power tube Q2 and the power tube Q4 are controlled to be turned on, and the self-oscillation waveform at the node M at this time is detected. This method requires relying on a large number of circuits to process the voltage at the node M, and there is a problem of low detection accuracy. Summary of the invention

[0003] The purpose of the embodiment of the present invention is to provide a foreign body detection circuit and chip to solve the above problem. The embodiment of the present invention achieves the above purpose through the following technical solutions.

[0004] The embodiment of the present invention provides a foreign body detection circuit, including: a foreign body detection circuit and a chip, including a first half-bridge and a second half-bridge connected in parallel between an input end and a common end, an inductor and a first capacitor connected in series are arranged between a half-bridge node of the first half-bridge and a half-bridge node of the second half-bridge, the first half-bridge includes a first switch tube and a second switch tube, and the second half-bridge includes a third switch tube and a fourth switch tube, including: a fifth switch tube and an energy-consuming element connected in series, connected between a voltage supply end and a first common point formed by the inductor and the first capacitor; a control module connected to the controlled end of each switch tube, controlling the fifth switch tube to turn off after turning on for a first preset time period, and cooperating with the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube to actively establish a starting voltage for the first common point through the voltage supply end; a detection module connected to the first common point, after the first switch tube is turned on for a first preset time period, the control module controls the on-off state of the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube to make the first common point oscillate freely, and the detection module detects the voltage of the first common point to determine whether there is a foreign body.

[0005] In some embodiments, the detection type of the detection module is an envelope detection method, and the detection module includes: a diode, whose anode is connected to the first common point; a first resistor and a second capacitor connected in parallel between the first common point and the common end; when a starting voltage state has been established at the first common point, the second capacitor has established an operating point.

[0006] In some embodiments, the control module controls the first switch tube and the fourth switch tube to be turned on for a second preset time period, and controls the second switch tube and the third switch tube to be turned off for a second preset time period; or, the control module controls the first switch tube and the fourth switch tube to be turned off for a second preset time period, and controls the second switch tube and the third switch tube to be turned on for a second preset time period.

[0007] In some embodiments, the first preset time period is within the second preset time period, or the second preset time period is before the first preset time period.

[0008] In some embodiments, the start time of the second preset time period is earlier than or equal to the start time of the first preset time period, and the end time of the second preset time period is equal to the end time of the first preset time period.

[0009] In some embodiments, the control module controls the first switch tube, the second switch tube, and the third switch tube to turn off for a third preset time period, and controls the fourth switch tube to turn on for a third preset time period; or, the control module controls the first switch tube, the third switch tube, and the fourth switch tube to turn off for a third preset time period, and controls the second switch tube to turn on for a third preset time period; wherein the start time and end time of the third preset time period are consistent with the first preset time period.

[0010] In some embodiments, within a first preset time period, the control module controls the first switch tube and the third switch tube to be turned off, and the second switch tube and the fourth switch tube to be turned on; or, within the first preset time period, the control module controls the first switch tube and the third switch tube to be turned on, and the second switch tube and the fourth switch tube to be turned off.

[0011] In some embodiments, a second common point formed by the second switch tube and the fourth switch tube has a second resistor disposed between the second common point and the common end.

[0012] In some embodiments, the energy consumption element is a resistor, and the larger the resistance value of the resistor is, the shorter the time to establish the starting voltage is.

[0013] An embodiment of the present invention further provides a foreign object detection chip, comprising the foreign object detection circuit described in any of the above embodiments.

[0014] Compared with the prior art, through the implementation of the foreign body detection circuit and chip provided in this embodiment, when performing foreign body detection, the fifth switch tube can be controlled to be turned on first until the first common point establishes the starting voltage, and then the fifth switch tube can be controlled to be turned off, so that the voltage at the first common point can oscillate freely, and the detection module detects the voltage of the first common point to determine whether there is a foreign body. Since the starting voltage can be directly provided to the first common point through the voltage supply terminal at this time, the first preset time period for the first common point to establish the starting voltage is extremely small, and there is no need to set up a detection circuit in the circuit to determine whether the first common point has reached the starting voltage, which effectively reduces the design difficulty, reduces the chip area, and effectively prevents the occurrence of false detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0016] Figure 1 is an application schematic diagram of the foreign body detection circuit provided in this embodiment;

[0017] Figure 2 is a structural schematic diagram of a foreign body detection circuit provided in this embodiment;

[0018] Figure 3 is a waveform diagram of a foreign body detection circuit provided in this embodiment;

[0019] Figure 4 is another structural schematic diagram of the foreign body detection circuit provided in this embodiment;

[0020] Figure 5 Schematic diagram of a waveform effect of the foreign object detection circuit provided in this embodiment. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The "coupling" or "connection" in the present invention includes both direct connection and indirect connection, such as connection through some active devices, passive devices or electrically conductive media; it may also include connection through other active devices or passive devices on the basis of achieving the same or similar functional purposes as is well known to those skilled in the art, such as connection through circuits or components such as switches and follower circuits.

[0023] In order to more clearly understand the technical solution of the foreign body detection circuit and chip provided by the present invention, the background technology is further explained. Specifically, the power tube Q1 and the power tube Q4 are first controlled to be turned on for a period of time, and the power tube Q2 and the power tube Q3 are turned on until a steady-state voltage is formed at the node M. Then the power tube Q1 is controlled to be turned off and the power tube Q2 is turned on. The voltage at the node M starts to oscillate, and then it is determined whether there is a foreign body based on the number of effective waves at the node M. In theory, this method meets the foreign body detection requirements. However, in practical applications, the inventors of the present invention have found through verification that when using this method, at least two conditions need to be met. The first condition is that a circuit specifically used to detect whether the voltage at the node M reaches a steady state needs to be set. The second condition is that the time period for controlling the power tube Q1 and the power tube Q4 to be turned on is long enough. In order to ensure whether the voltage at the detection node M reaches a steady state, it is usually necessary to design a redundant circuit to prevent low detection accuracy. In addition, in actual foreign body detection, it is necessary to wait for a long time for the voltage at the node M to reach a steady state. This is obviously not conducive to rapid detection of foreign bodies and cannot achieve timely detection of foreign bodies.

[0024] In summary, the inventors of the present invention have discovered the above problems and based on this, proposed a foreign body detection circuit and chip provided in this embodiment. For the specific implementation method of the foreign body detection circuit and chip, refer to the description of the following embodiment.

[0025] See also Figure 2The embodiment of the present invention provides a foreign body detection circuit, which includes a first half bridge 11 and a second half bridge 12 connected in parallel between an input terminal VIN and a common terminal GND, an inductor L and a first capacitor C1 connected in series are provided between a half bridge node of the first half bridge 11 and a half bridge node of the second half bridge 12, the first half bridge 11 includes a first switch tube K1 and a second switch tube K2, and the second half bridge 12 includes a third switch tube K3 and a fourth switch tube K4, and the foreign body detection circuit also includes: a fifth switch tube K5 and an energy consumption element 13 connected in series, connected between a voltage supply terminal VX and a first common point X1 formed by the inductor L and the first capacitor C1; and each switch The controlled ends of the switch tubes are respectively connected to the control modules 14, which control the fifth switch tube K5 to be turned on and then turned off after the first preset time period, and cooperate with the first switch tube K1, the second switch tube K2, the third switch tube K3, and the fourth switch tube K4 to actively establish a starting voltage for the first common point X1 through the voltage supply end VX; the detection module 15 connected to the first common point X1, after the first switch tube K1 is turned on for the first preset time period, the control module 14 controls the on and off states of the first switch tube K1, the second switch tube K2, the third switch tube K3, and the fourth switch tube K4 to make the first common point X1 oscillate freely, and the detection module 15 detects the voltage of the first common point X1 to determine whether there is a foreign object.

[0026] In this embodiment, the half-bridge node of the first half-bridge 11 is a common point formed by the first switch tube K1 and the second switch tube K2, and the half-bridge node of the second half-bridge 12 is a common point formed by the third switch tube K3 and the fourth switch tube K4. It should be noted that the "common point" described in this embodiment can be used to facilitate the description of the circuit structure, and should not be limited to a specific intersection formed by connecting two wire bodies, but can also be a wire body extended on the basis of a specific intersection formed by connecting two wire bodies. Here, only the "common point" is used to describe the circuit structure of the foreign body detection circuit.

[0027] In this embodiment, the first switch tube K1, the second switch tube K2, the third switch tube K3, and the fourth switch tube K4 may include MOS tubes (Metal-Oxide-Semiconductor Field-Effect Transistor, metal-oxide semiconductor field effect transistor), triodes, BJT tubes (Bipolar Junction Transistor, bipolar junction transistor), etc. The first switch tube K1, the second switch tube K2, the third switch tube K3, and the fourth switch tube K4 are of the same switch type.

[0028] In this embodiment, the inductor L and the first capacitor C1 form a first common point X1. Regarding the series relationship between the inductor L and the first capacitor C1, the first common point X1, the energy consumption element 13, the fifth switch tube K5, and the voltage supply end VX can be connected in sequence, or the first common point X1, the fifth switch tube K5, the energy consumption element 13, and the voltage supply end VX can be connected in sequence.

[0029] In this embodiment, the energy consumption element 13 may be a resistor, and the resistance value of the resistor may be configured based on actual needs.

[0030] In this embodiment, the control module 14 can control the on / off states of the first switch tube K1, the second switch tube K2, the third switch tube K3, the fourth switch tube K4, and the fifth switch tube K5. When performing foreign object detection, the fifth switch tube K5 can be controlled to be turned on first until the first common point X1 establishes a starting voltage, and then the fifth switch tube K5 can be controlled to be turned off, so that the voltage at the first common point X1 can oscillate freely, and the detection module 15 detects the voltage of the first common point X1 to determine whether there is a foreign object. Since the starting voltage can be directly provided to the first common point X1 through the voltage supply terminal VX at this time, the first preset time period for the first common point X1 to establish the starting voltage is extremely small, and there is no need to set a detection circuit in the circuit specifically to determine whether the first common point X1 reaches the starting voltage, which effectively reduces the design difficulty, reduces the chip area, and effectively prevents the occurrence of false detection.

[0031] It should be noted that the detection module 15 can determine whether there is a foreign object by detecting the voltage waveform at the first common point X1. The detection module 15 can adopt effective waveform counting, envelope detection, etc. The specific detection method and circuit structure of the detection module 15 are not specifically limited here.

[0032] The inventors of the present invention have found through actual measurements that the envelope obtained by performing envelope detection on the voltage waveform of the first common point X1 is as follows: Figure 3 As shown in (a), the envelope should be close to the upper and lower edges of the voltage waveform. However, in actual applications, if there is a capacitive device in the detection module 15, the capacitor in the detection module 15 needs to be charged to establish the working point in the early stage of the oscillation circuit, which causes the voltage after the oscillation waveform detection to be inconsistent with the expected voltage waveform. The obtained envelope is as follows: Figure 3 As shown in (b), at this time, the detected envelope waveform and the oscillation waveform peak value will be seriously distorted, which will make it impossible to detect foreign objects.

[0033] In some embodiments, Figure 4As shown, the detection type of the detection module 15 can be an envelope detection method, and the detection module 15 can include: a diode D, whose anode is connected to the first common point X1; a first resistor R1 and a second capacitor C2 connected in parallel between the first common point X1 and the common terminal GND; when a starting voltage state is established at the first common point X1, the second capacitor C2 has established a working point.

[0034] In this embodiment, when the first common point X1 has established a starting voltage state, the second capacitor C2 has established a working point. When performing envelope detection, the cathode of the diode D can be used as the detection terminal VY. At this time, the edge envelope detected by the envelope detection method is basically close to the edge part of the voltage oscillation wave, and the detection result is more accurate.

[0035] It should be noted that in this embodiment, whether the effective wave counting method or the envelope detection method is used, the accuracy of foreign body detection can be improved. Specifically, when the effective wave counting method is used, the starting voltage of the first common point X1 is used as the starting point of the free oscillation of the non-legacy common point. Since the frequency of the free oscillation is consistent with the counting frequency, it is convenient to set the peak area of ​​each count to be basically consistent with the clock pulse width area. In actual application, the number of effective waves obtained by counting is not prone to error. At the same time, when the envelope detection method is used, since the capacitive device in the detection module 15 has pre-established the working point before detecting the envelope, there is no need to charge the capacitive device in the detection module 15 in the subsequent oscillation, such as Figure 5 As shown, in this way, the envelope obtained under free oscillation is basically consistent with the edge of the oscillation waveform, thereby greatly improving the detection accuracy under the envelope detection method.

[0036] In some embodiments, the control module 14 can control the first switch tube K1 and the fourth switch tube K4 to be turned on for the second preset time period, and control the second switch tube K2 and the third switch tube K3 to be turned off for the second preset time period; or, the control module 14 can control the first switch tube K1 and the fourth switch tube K4 to be turned off for the second preset time period, and control the second switch tube K2 and the third switch tube K3 to be turned on for the second preset time period.

[0037] In this embodiment, when the control module 14 controls the first switch tube K1 and the fourth switch tube K4 to turn on for the second preset time period, and controls the second switch tube K2 and the third switch tube K3 to turn off for the second preset time period, the input terminal VIN, the first switch tube K1, the inductor L, the energy consumption element 13 and the fifth switch tube K5 connected in series, and the voltage supply terminal VX can form a first path, and the input terminal VIN, the first switch tube K1, the inductor L, the first capacitor C1, the fourth switch tube K4, and the common terminal GND can form a second path. When the control module 14 controls the first switch tube K1 and the fourth switch tube K4 to turn off for the second preset time period, and controls the second switch tube K2 and the third switch tube K3 to turn on for the second preset time period, at this time, the input terminal VIN, the third switch tube K3, the first capacitor C1, the energy consumption element 13 and the fifth switch tube K5 connected in series, and the voltage supply terminal VX can form a third path, and the input terminal VIN, the third switch tube K3, the first capacitor C1, the inductor L, the second switch tube K2, and the common terminal GND can form a fourth path. In the above-mentioned path forming process, based on the joint action of the input terminal VIN and the voltage supply terminal VX, the starting voltage can be established for the first common point X1 more quickly.

[0038] In some embodiments, the first preset time period is within the second preset time period, or the second preset time period is before the first preset time period.

[0039] Specifically, the first preset time period can be within the second preset time period, which means that the first preset time period can be in any interval within the second time period. The control module 14 can control the fifth switch tube K5 to be turned on for the first preset time period within the second preset time period when the first switch tube K1 and the fourth switch tube K4 are turned on and the second switch tube K2 and the third switch tube K3 are turned off. Alternatively, the control module 14 can control the fifth switch tube K5 to be turned on for the first preset time period within the second preset time period when the first switch tube K1 and the fourth switch tube K4 are turned off and the second switch tube K2 and the third switch tube K3 are turned on.

[0040] The second preset time period before the first preset time period can be indicated, and the first preset time period is performed after the second preset time period. The control module 14 can control the fifth switch tube K5 to be turned on for the first preset time period after the second preset time period in which the first switch tube K1 and the fourth switch tube K4 are turned on and the second switch tube K2 and the third switch tube K3 are turned off. Alternatively, the control module 14 can control the first switch tube K1 and the fourth switch tube K4 to be turned off and the second switch tube K2 and the third switch tube K3 to be turned off, and then control the fifth switch tube K5 to be turned on for the first preset time period. At this time, it is preferred that the second preset time period is continuous with the first preset time period without any gap.

[0041] In some embodiments, the start time of the second preset time period may be earlier than or equal to the start time of the first preset time period, and the end time of the second preset time period may be equal to the end time of the first preset time period. That is, the control module 14 may control the first switch tube K1 and the fourth switch tube K4 to be turned on, and the moment when the second switch tube K2 and the third switch tube K3 are turned off may be earlier than or equal to the moment when the fifth switch tube K5 is turned on. Alternatively, the control module 14 may control the first switch tube K1 and the fourth switch tube K4 to be turned off, and the moment when the second switch tube K2 and the third switch tube K3 are turned on may be earlier than or equal to the moment when the fifth switch tube K5 is turned on, and the fifth switch tube K5 is controlled to be turned on for the first preset time period.

[0042] In some embodiments, the control module 14 can control the first switch tube K1, the second switch tube K2, and the third switch tube K3 to turn off for the third preset time period, and control the fourth switch tube K4 to turn on for the third preset time period; or, the control module 14 can control the first switch tube K1, the third switch tube K3, and the fourth switch tube K4 to turn off for the third preset time period, and control the second switch tube K2 to turn on for the third preset time period; wherein the start time and the end time of the third preset time period are consistent with the first preset time period.

[0043] In this embodiment, when the control module 14 controls the first switch tube K1, the second switch tube K2, and the third switch tube K3 to turn off the third preset time period, and controls the fourth switch tube K4 to turn on the third preset time period, the voltage supply terminal VX, the series-connected energy-consuming element 13 and the fifth switch tube K5, the first capacitor C1, the fourth switch tube K4, and the common terminal GND form a fifth path. When the control module 14 controls the first switch tube K1, the third switch tube K3, and the fourth switch tube K4 to turn off the third preset time period, and controls the second switch tube K2 to turn on the third preset time period, the voltage supply terminal VX, the series-connected energy-consuming element 13 and the fifth switch tube K5, the inductor L, the second switch tube K2, and the common terminal GND form a sixth path.

[0044] In some embodiments, within a first preset time period, the control module 14 can control the first switch tube K1 and the third switch tube K3 to be turned off, and the second switch tube K2 and the fourth switch tube K4 to be turned on; or, within the first preset time period, the control module 14 can control the first switch tube K1 and the third switch tube K3 to be turned on, and the second switch tube K2 and the fourth switch tube K4 to be turned off.

[0045] In this embodiment, when the control module 14 controls the first switch tube K1 and the third switch tube K3 to turn off and the second switch tube K2 and the fourth switch tube K4 to turn on in the first preset time period, the voltage supply terminal VX, the energy consumption element 13 connected in series, the fifth switch tube K5, the second switch tube K2, and the common terminal GND form a seventh path, and the voltage supply terminal VX, the energy consumption element 13 connected in series, the fifth switch tube K5, the fourth switch tube K4, and the common terminal GND form an eighth path. In the first preset time period, when the control module 14 controls the first switch tube K1 and the third switch tube K3 to turn on and the second switch tube K2 and the fourth switch tube K4 to turn off, the input terminal VIN, the first switch tube K1, the inductor L, the energy consumption element 13 connected in series, the fifth switch tube K5, and the voltage supply terminal VX form a ninth path, and the input terminal VIN, the third switch tube K3, the first capacitor C1, the energy consumption element 13 connected in series, the fifth switch tube K5, and the voltage supply terminal VX form a tenth path.

[0046] In some embodiments, after the starting voltage is established at the first common point X1, the second switch tube K2 and the fourth switch tube K4 can be controlled to be turned on, and the first switch tube K1, the third switch tube K3, and the fifth switch tube K5 can be turned off, so that the first common point X1 is in a free oscillation state.

[0047] In some embodiments, the fourth switch tube K4 and the fifth switch tube K5 can be controlled to be turned on, and the first switch tube K1, the second switch tube K2, and the third switch tube K3 can be turned off. After the starting voltage is established at the first common point X1, the first switch tube K1, the third switch tube K3, and the fifth switch tube K5 are controlled to be turned off, and the second switch tube K2 and the fourth switch tube K4 are turned on, so that the first common point X1 is in a free oscillation state.

[0048] In some embodiments, Figure 2 As shown, the second common point X2 formed by the second switch tube K2 and the fourth switch tube K4, and a second resistor R2 is arranged between the second common point X2 and the common terminal GND.

[0049] In this embodiment, based on the second resistor R2, current detection can be implemented based on the second common point X2 to determine whether the current is abnormal during the wireless charging process, and the oscillation amplitude can be adjusted based on the second resistor R2, so that a suitable oscillation waveform can be easily obtained at the first common point X1.

[0050] In some embodiments, the energy consumption element 13 may be a resistor. The larger the resistance value of the resistor is, the shorter the time to establish the starting voltage is.

[0051] In some embodiments, the detection module 15 may further include a valid wave counting method.

[0052] An embodiment of the present invention further provides a foreign object detection chip, which includes a foreign object detection circuit as described in any of the above embodiments.

[0053] Since the circuit structure and working mode of the foreign matter detection circuit in the foreign matter detection chip in this embodiment are the same as those of the foreign matter detection circuit in the previous embodiment, they will not be described in detail here.

[0054] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such 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 invention, and should all be included in the protection scope of the present invention.

Claims

1. A foreign body detection circuit, comprising a first half bridge and a second half bridge connected in parallel between an input end and a common end, an inductor and a first capacitor connected in series are provided between a half bridge node of the first half bridge and a half bridge node of the second half bridge, the first half bridge comprises a first switch tube and a second switch tube, the second half bridge comprises a third switch tube and a fourth switch tube, characterized in that: include: A fifth switch tube and an energy-consuming element connected in series are connected between a voltage supply terminal and a first common point formed by the inductor and the first capacitor; a control module connected to the controlled end of each switch tube, controlling the fifth switch tube to be turned on for a first preset time period and then turned off, cooperating with the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube to actively establish a starting voltage for the first common point through the voltage supply end; The detection module connected to the first common point, after the first switch tube is turned on for a first preset time period, the control module controls the on and off states of the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube to allow the first common point to oscillate freely, and the detection module detects the voltage of the first common point to determine whether there is a foreign object.

2. The foreign body detection circuit according to claim 1, characterized in that: The detection type of the detection module is envelope detection, and the detection module includes: a diode, an anode of which is connected to the first common point; A first resistor and a second capacitor are connected in parallel between the first common point and a common terminal; when a starting voltage state is established at the first common point, the second capacitor has established a working point.

3. The foreign body detection circuit according to claim 1, characterized in that: The control module controls the first switch tube and the fourth switch tube to be turned on for the second preset time period, and controls the second switch tube and the third switch tube to be turned off for the second preset time period; or, the control module controls the first switch tube and the fourth switch tube to be turned off for the second preset time period, and controls the second switch tube and the third switch tube to be turned on for the second preset time period.

4. The foreign body detection circuit according to claim 3, characterized in that: The first preset time period is within the second preset time period, or the second preset time period is before the first preset time period.

5. The foreign body detection circuit according to claim 3, characterized in that: The start time of the second preset time period is earlier than or equal to the start time of the first preset time period, and the end time of the second preset time period is equal to the end time of the first preset time period.

6. The foreign body detection circuit according to claim 1, characterized in that: The control module controls the first switch tube, the second switch tube, and the third switch tube to be turned off for a third preset time period, and controls the fourth switch tube to be turned on for the third preset time period; or, the control module controls the first switch tube, the third switch tube, and the fourth switch tube to be turned off for a third preset time period, and controls the second switch tube to be turned on for the third preset time period; The start time and end time of the third preset time period are consistent with those of the first preset time period.

7. The foreign body detection circuit according to claim 1, characterized in that: During the first preset time period, the control module controls the first switch tube and the third switch tube to be turned off, and the second switch tube and the fourth switch tube to be turned on; or, during the first preset time period, the control module controls the first switch tube and the third switch tube to be turned on, and the second switch tube and the fourth switch tube to be turned off.

8. The foreign body detection circuit according to claim 1, characterized in that: The second switch tube and the fourth switch tube form a second common point, and a second resistor is arranged between the second common point and the common end.

9. The foreign body detection circuit according to claim 1, characterized in that: The energy consumption element is a resistor, and the greater the resistance of the resistor, the shorter the time to establish the starting voltage.

10. A foreign body detection chip, characterized in that: The invention comprises a foreign body detection circuit as claimed in any one of claims 1 to 9.

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