Current detection circuit and electronic equipment

Abstract

The utility model discloses a current detection circuit and electronic equipment, and belongs to the technical field of electronic circuits. The switching circuit responds to the control signal and transmits power supply direct current through the first field effect transistor; the sampling circuit is used for sampling current flowing through the first field effect transistor so as to output a sampling signal; the control circuit outputs a control signal and obtains a current value according to the sampling signal; therefore, a small resistor does not need to be arranged on the power supply main loop, voltage reduction of post-ground stage power supply caused by voltage drop generated by the small resistor is avoided, and energy loss is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electronic circuits, and particularly relates to a current detection circuit and an electronic device. BACKGROUND

[0002] A related current detection circuit usually connects a small resistor in series on a main circuit in which current needs to be measured, and then processes the voltage on the resistor to convert the size of the corresponding current. However, the resistor itself generates a voltage drop, which causes the voltage of the power supply rail to decrease, resulting in additional energy loss.

[0003] Therefore, the related current detection circuit affects the supply voltage and has large energy loss. CONTENT OF THE UTILITY MODEL

[0004] The application aims to provide a current detection circuit and an electronic device, and aims to solve the problem of the related current detection circuit affecting the supply voltage and having large energy loss.

[0005] The application provides a current detection circuit, which comprises a switching circuit, a sampling circuit and a control circuit.

[0006] The switching circuit comprises a first field effect transistor connected in series on a power supply main circuit.

[0007] The switching circuit is configured to transmit power direct current through the first field effect transistor in response to a control signal.

[0008] The sampling circuit is connected with the switching circuit and is configured to sample the current flowing through the first field effect transistor to output a sampling signal.

[0009] The control circuit is connected with the switching circuit and the sampling circuit and is configured to output a control signal and obtain a current value according to the sampling signal.

[0010] In one of the embodiments, the application further comprises:

[0011] A temperature detection circuit is configured to detect temperature to output a temperature detection signal.

[0012] The control circuit is specifically configured to output a control signal and obtain a current value according to the temperature detection signal and the sampling signal.

[0013] In one of the embodiments, the sampling circuit comprises:

[0014] A first follower is connected with the source of the first field effect transistor and is configured to follow the source voltage of the first field effect transistor to output a first voltage.

[0015] a second follower connected with the drain of the first field effect transistor, for following the drain voltage of the first field effect transistor to output a second voltage;

[0016] a subtracter connected with the first follower, the second follower and the control circuit, for subtracting the second voltage from the first voltage to output a sampling signal.

[0017] In one of the embodiments, the first follower comprises a first operational amplifier and a first resistor;

[0018] a non-inverting input terminal of the first operational amplifier constitutes an input terminal of the first follower, and is connected with the source of the first field effect transistor to access the source voltage of the first field effect transistor;

[0019] an output terminal of the first operational amplifier and a first terminal of the first resistor are connected together and constitute an output terminal of the first follower, and are connected with the subtracter to output the first voltage;

[0020] an inverting input terminal of the first operational amplifier is connected with a second terminal of the first resistor.

[0021] In one of the embodiments, the second follower comprises a second operational amplifier and a second resistor;

[0022] a non-inverting input terminal of the second operational amplifier constitutes an input terminal of the second follower, and is connected with the drain of the first field effect transistor to access the drain voltage of the first field effect transistor;

[0023] an output terminal of the second operational amplifier and a first terminal of the second resistor are connected together and constitute an output terminal of the second follower, and are connected with the subtracter to output the second voltage;

[0024] an inverting input terminal of the second operational amplifier is connected with a second terminal of the second resistor.

[0025] In one of the embodiments, the subtracter comprises a third operational amplifier, a third resistor and a fourth resistor;

[0026] a non-inverting input terminal of the third operational amplifier constitutes a first input terminal of the subtracter, and is connected with the second follower to access the second voltage;

[0027] a first terminal of the third resistor constitutes a second input terminal of the subtracter, and is connected with the first follower to access the first voltage;

[0028] a second terminal of the third resistor is connected with a first terminal of the fourth resistor and an inverting input terminal of the third operational amplifier;

[0029] The output end of the third operational amplifier and the second end of the fourth resistance are connected and jointly constitute the output end of the subtractor, and are connected with the control circuit to output the sampling signal.

[0030] In one of the embodiments, the switch circuit comprises the first field effect transistor, the second field effect transistor, the third field effect transistor, the voltage stabilizing tube, the sixth resistance, the seventh resistance, the eighth resistance and the ninth resistance.

[0031] The first end of the seventh resistance constitutes the control end of the switch circuit, and is connected with the control circuit to access the control signal.

[0032] The source of the first field effect transistor and the negative pole of the voltage stabilizing tube are connected and jointly constitute the input end of the switch circuit, and are connected with the sampling circuit to access the power direct current and output the source voltage of the first field effect transistor.

[0033] The drain of the first field effect transistor and the first end of the ninth resistance are connected and constitute the input end of the switch circuit, and are connected with the sampling circuit to output the power direct current and output the drain voltage of the first field effect transistor.

[0034] The second end of the seventh resistance is connected with the gate of the second field effect transistor and the first end of the eighth resistance, the drain of the second field effect transistor is connected with the first end of the sixth resistance and the gate of the third field effect transistor, the drain of the third field effect transistor is connected with the second end of the ninth resistance, the second end of the sixth resistance is connected with the positive pole of the voltage stabilizing tube and the gate of the first field effect transistor, and the source of the second field effect transistor, the second end of the eighth resistance and the source of the third field effect transistor are commonly connected to the power supply ground.

[0035] In one of the embodiments, the switch circuit comprises the first field effect transistor and the fifth resistance.

[0036] The source of the first field effect transistor and the first end of the fifth resistance are connected and jointly constitute the input end of the switch circuit, and are connected with the sampling circuit to access the power direct current and output the source voltage of the first field effect transistor.

[0037] The drain of the first field effect transistor constitutes the input end of the switch circuit, and is connected with the sampling circuit to output the power direct current and output the drain voltage of the first field effect transistor.

[0038] The gate of the first field effect transistor and the second end of the fifth resistance are connected and jointly constitute the control end of the switch circuit, and are connected with the control circuit to access the control signal.

[0039] In one of the embodiments, the control circuit comprises a microprocessor;

[0040] A first general input and output end of the microprocessor constitutes a sampling signal input end of the control circuit, and is connected with the sampling circuit to access the sampling signal;

[0041] A second general input and output end of the microprocessor constitutes a control signal output end of the control circuit, and is connected with the switch circuit to output the switch signal.

[0042] The utility model embodiment further provides an electronic device, the electronic device includes the current detection circuit.

[0043] The utility model embodiment compared with prior art has the beneficial effects that: since the switch circuit includes the first field effect tube which is connected in series on the power supply main loop, and the switch circuit responds to the control signal, and transmits the power supply direct current through the first field effect tube, the sampling circuit samples the current which flows through the first field effect tube to output the sampling signal, thereby, it is not necessary to set up small resistance on the power supply main loop, and the voltage reduction of the power supply after the ground stage caused by the voltage drop of the small resistance itself is avoided, and the energy loss is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical utility model in the utility model embodiment, the drawings needed to be used in the embodiment description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can be obtained according to these drawings without creating labor.

[0045] Figure 1 A structural schematic diagram of the current detection circuit provided by an embodiment of the application is shown in the figure.

[0046] Figure 2 Another structural schematic diagram of the current detection circuit provided by an embodiment of the application is shown in the figure.

[0047] Figure 3 A curve diagram of the on-resistance changing with the junction temperature provided by an embodiment of the application is shown in the figure.

[0048] Figure 4 A partial example circuit schematic diagram of the current detection circuit provided by an embodiment of the application is shown in the figure.

[0049] Figure 5 Another partial example circuit schematic diagram of the current detection circuit provided by an embodiment of the application is shown in the figure. DETAILED DESCRIPTION

[0050] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, further detailed description will be made in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not intended to limit the present application.

[0051] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0052] It should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0053] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0054] Figure 1 The structure diagram of the current detection circuit provided by the preferred embodiment of the present application is shown, only the parts related to the present embodiment are shown for the convenience of description, and the details are as follows:

[0055] The current detection circuit includes a switching circuit 01, a sampling circuit 02 and a control circuit 03.

[0056] The switching circuit 01 includes a first field effect transistor connected in series on the power supply main circuit.

[0057] The switching circuit 01 is used to transmit the power supply direct current VCC through the first field effect transistor in response to the control signal.

[0058] The sampling circuit 02 is connected with the switching circuit 01 and is used to sample the current flowing through the first field effect transistor to output a sampling signal.

[0059] The control circuit 03 is connected with the switching circuit 01 and the sampling circuit 02, and is used to output the control signal and obtain the current value according to the sampling signal.

[0060] It can be understood that the power supply direct current VCC is used to supply power to the load.

[0061] Many electronic devices are battery-powered low-power products, and the current and power consumption of each module are very concerned, and the working current state of each module is also directly related to the stability of long-term work of the product. The overall hardware architecture of the electronic device (such as a smart door lock) usually contains a large number of modules related to user interaction, and some of the modules have high power consumption, so they can only work in the power-on mode. In this case, a first field effect transistor is used to build a switching circuit 01 to realize power-off and power-on control of each circuit module.

[0062] By differentially amplifying the source and drain points in the fully on state of the first field effect transistor, the voltage mapped by the current flowing through the first field effect transistor can be obtained. The bulk resistance of the fully on first field effect transistor is relatively small, and the consistency is slightly poor, generally in the level of tens of mΩ to hundreds of mΩ. The amplified voltage value (sampling signal) represents the current flowing through the MOS tube under the current condition.

[0063] The application detects the current flowing through the first field effect transistor by detecting the voltage. In specific implementation, a threshold value can be set based on this, and when the current value given by the conventional scheme deviates too much, such as a change of more than ±30%, the application can give the user an early warning through the application.

[0064] When the above current detection circuit is applied to a smart door lock, there are many peripheral modules, and the smart door lock is a strong interaction product, and it is also a battery-powered low-power product. Once the hardware of any module fails, it may cause abnormal module working current (too large or too small). Light: the abnormal working current will eventually affect the product's endurance time and be quickly perceived by the user; heavy: directly module function failure, affecting user experience; the application quickly identifies abnormal function modules by current size, and facilitates timely power cut-off in the case of excessive current, and facilitates timely reporting of abnormalities and warning of failure in the case of small current.

[0065] As shown in Figure 2 The current detection circuit further includes a temperature detection circuit 04.

[0066] The temperature detection circuit 04 is configured to detect temperature to output a temperature detection signal.

[0067] The control circuit 03 is specifically configured to output a control signal, and obtain a current value according to the temperature detection signal and the sampling signal.

[0068] It can be understood that the temperature can be an ambient temperature or a temperature of the first field effect transistor.

[0069] The on-resistance of the first field effect transistor is related to the following factors: 1) channel resistance. Channel width and length: The channel resistance is the main component of the on-resistance of the field effect transistor; the wider the channel width and the shorter the length, the smaller the channel resistance, and thus the smaller the on-resistance; material properties: such as the resistivity of the conductive layer, which also affects the size of the channel resistance. 2) Control voltage (Vgs) The on-resistance of the MOS tube is closely related to the control voltage (especially the gate-source voltage Vgs); when Vgs increases, the channel conductivity increases, and the on-resistance usually decreases; this is because the increase of Vgs causes more carriers to be attracted into the channel, thereby reducing the channel resistance. 3) Temperature. The on-resistance of the field effect transistor is also affected by temperature; as the temperature rises, the resistivity of the material increases, resulting in an increase in the on-resistance; because the scattering of carriers is enhanced at high temperatures, the mobility decreases, thereby increasing the resistance.

[0070] In summary, the on-resistance of the MOS tube is affected by factors such as channel resistance, control voltage, and temperature. In practical applications, these factors need to be considered to select and design appropriate field effect transistors and their circuits to ensure the performance and stability of the circuit. The channel resistance is affected by the consistency of the materials of the field effect transistor chip itself, and the control voltage of the gate can be adjusted by adjusting the input voltage of the control circuit 03 to achieve uniformity. In terms of temperature, the mapping relationship between current and voltage can be done well by calibrating the voltage values at different temperature environments.

[0071] The calibration method is shown below.

[0072] The size of the on-resistance does not change significantly with the increase of the on-current, or the small resistance change can be ignored.

[0073] The size of the on-resistance increases approximately linearly with the change of the chip junction temperature. As shown in Figure 3 The linear mapping relationship between on-resistance and temperature can be approximately obtained. The slope is fixed, but due to individual differences between materials, even if the temperature is the same, the default on-resistance corresponding to different materials will also be different.

[0074] During the development and debugging phase, under the condition of a fixed gate-source voltage difference, the junction temperature of the field effect transistor and the environmental temperature are tested under normal load conditions, a one-to-one mapping relationship is established (such as an environmental temperature of 20 degrees, corresponding to an initial junction temperature of 30 degrees; an environmental temperature of 30 degrees, corresponding to an initial junction temperature of 40 degrees, etc.), and the mapping relationship is stored in the register of the microprocessor of the control circuit 03, waiting for calling during production.

[0075] The mapping debugging method is shown below.

[0076] In the factory production process, the switch circuit 01 is turned on, and the normal later stage load circuit is connected, at this time, the microprocessor in the control circuit 03 reads the voltage value after differential amplification, and the on-resistance of the field effect tube under the environment temperature can be calculated reversely, and the slope change of the on-resistance with the temperature change is known (as shown in the figure) Figure 3 The current value of the field effect tube corresponding to the environment temperature can be obtained.

[0077] Thus, the calibration process of the two variables of temperature and individual difference of bulk resistance is realized.

[0078] By considering the influence of the environment temperature in the process of obtaining the on-resistance of the first field effect tube, the accuracy of current detection is improved.

[0079] As shown in the figure Figure 3 The sampling circuit 02 includes a first follower 021, a second follower 022 and a subtractor 023.

[0080] The first follower 021 is connected with the source of the first field effect tube, and is used for following the source voltage of the first field effect tube to output a first voltage.

[0081] The second follower 022 is connected with the drain of the first field effect tube, and is used for following the drain voltage of the first field effect tube to output a second voltage.

[0082] The subtractor 023 is connected with the first follower 021, the second follower 022 and the control circuit 03, and is used for subtracting the second voltage from the first voltage to output a sampling signal.

[0083] By setting two followers, the stability of the sampling circuit 02 is improved, so that the accuracy of current detection is improved.

[0084] Figure 4 Part of the example circuit structure of the current detection circuit provided by the embodiment of the utility model is shown, Figure 5 Another part of the example circuit structure of the current detection circuit provided by the embodiment of the utility model is shown, for the convenience of description, only the part related to the embodiment of the utility model is shown, and the details are as follows:

[0085] As shown in the figure Figure 4 And Figure 5 The first follower 021 includes a first operational amplifier U1 and a first resistor R1.

[0086] The non-inverting input terminal of the first operational amplifier U1 constitutes the input terminal of the first follower 021, and is connected with the source of the first field effect tube to access the source voltage of the first field effect tube; the output terminal of the first operational amplifier U1 is connected with the first end of the first resistor R1 and constitutes the output terminal of the first follower 021 together, and is connected with the subtracter 023 to output the first voltage; the inverting input terminal of the first operational amplifier U1 is connected with the second end of the first resistor R1.

[0087] The working current drawn by the operational amplifier in the first follower 021 is extremely small, which can isolate the influence of the action of the sampling circuit on the switching circuit, and the circuit is simple and reliable.

[0088] As shown in Figure 4 and Figure 5 , the second follower 022 includes a second operational amplifier U2 and a second resistor R2.

[0089] The non-inverting input terminal of the second operational amplifier U2 constitutes the input terminal of the second follower 022, and is connected with the drain of the first field effect tube to access the drain voltage of the first field effect tube; the output terminal of the second operational amplifier U2 is connected with the first end of the second resistor R2 and constitutes the output terminal of the second follower 022 together, and is connected with the subtracter 023 to output the second voltage; the inverting input terminal of the second operational amplifier U2 is connected with the second end of the second resistor R2.

[0090] The working current drawn by the operational amplifier in the second follower 022 is extremely small, which can isolate the influence of the action of the sampling circuit on the switching circuit, and the circuit is simple and reliable.

[0091] As shown in Figure 4 and Figure 5 , the subtracter 023 includes a third operational amplifier U3, a third resistor R3 and a fourth resistor R4.

[0092] The non-inverting input terminal of the third operational amplifier U3 constitutes the first input terminal of the subtracter 023, and is connected with the second follower 022 to access the second voltage; the first end of the third resistor R3 constitutes the second input terminal of the subtracter 023, and is connected with the first follower 021 to access the first voltage; the second end of the third resistor R3 is connected with the first end of the fourth resistor R4 and the inverting input terminal of the third operational amplifier U3; the output terminal of the third operational amplifier U3 is connected with the second end of the fourth resistor R4 and constitutes the output terminal of the subtracter 023 together, and is connected with the control circuit 03 to output the sampling signal.

[0093] The subtracter 023 has simple hardware and low cost.

[0094] As shown in Figure 4 and Figure 5 , the control circuit 03 includes a microprocessor U4.

[0095] The first general-purpose input / output terminal P1.0 of the microprocessor U4 constitutes the sampling signal input terminal of the control circuit 03 and is connected to the sampling circuit 02 to receive the sampling signal; the second general-purpose input / output terminal P1.1 of the microprocessor U4 constitutes the control signal output terminal of the control circuit 03 and is connected to the switching circuit 01 to output the switching signal.

[0096] The control circuit 03 has simple hardware and low cost.

[0097] like Figure 5 As shown, the switching circuit 01 includes a first field-effect transistor M1, a second field-effect transistor M2, a third field-effect transistor M3, a Zener diode Z1, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9.

[0098] The first terminal of the seventh resistor R7 forms the control terminal of the switching circuit 01 and is connected to the control circuit 03 to receive the control signal; the source of the first field-effect transistor M1 and the negative terminal of the Zener diode Z1 are connected and together form the input terminal of the switching circuit 01, which is connected to the sampling circuit 02 to receive the DC power supply VCC and output the source voltage of the first field-effect transistor M1; the drain of the first field-effect transistor M1 and the first terminal of the ninth resistor R9 are connected and form the input terminal of the switching circuit 01, which is connected to the sampling circuit 02 to output the DC power supply VCC and output the source voltage of the first field-effect transistor M1. The drain voltage of transistor M1; the second end of the seventh resistor R7 is connected to the gate of the second field-effect transistor M2 and the first end of the eighth resistor R8; the drain of the second field-effect transistor M2 is connected to the first end of the sixth resistor R6 and the gate of the third field-effect transistor M3; the drain of the third field-effect transistor M3 is connected to the second end of the ninth resistor R9; the second end of the sixth resistor R6 is connected to the positive terminal of the Zener diode Z1 and the gate of the first field-effect transistor M1; the source of the second field-effect transistor M2, the second end of the eighth resistor R8, and the source of the third field-effect transistor M3 are all connected to the power supply ground.

[0099] It should be noted that the switching circuit 01 may also include a first capacitor C1. The first terminal of the first capacitor C1 is connected to the second terminal of the seventh resistor R7, the gate of the second field-effect transistor M2, and the first terminal of the eighth resistor R8; the second terminal of the first capacitor C1 is connected to the power supply ground. The first capacitor C1 and the seventh resistor R7 form an RC charging circuit, which plays a role in soft start-up, slowing down the conduction process of the first field-effect transistor M2, reducing the possibility of overshoot at the switching edge, and preventing damage to subsequent circuits.

[0100] For the voltage of the power supply direct current VCC is obviously higher than the control voltage variation range, it is needed to use multiple field effect tubes to build a switch circuit 01 to control the conduction and closing of the power supply main loop. In the case of the power supply direct current VCC is battery power supply, the voltage of the power supply rail will change with the charging and discharging of the battery, at this time, the voltage between the gate and the source of the first field effect tube M1 can be stabilized by adding a stabilizing tube Z1 in the control circuit 03, thereby improving the stability of the switch circuit 01.

[0101] It should be noted that in the case of the control signal being pulled low, the second field effect tube M2 is cut off, the first field effect tube M1 is cut off, and the switch circuit 01 is disconnected. The third field effect tube M3 is turned on, and the inductive load and the capacitive load can be quickly discharged through the ninth resistor R9. In the case of the control signal being pulled high, the second field effect tube M2 is turned on, the first field effect tube M1 is turned on, and the switch circuit 01 is turned on. The third field effect tube M3 is cut off.

[0102] As shown in Figure 4 , the switch circuit 01 includes the first field effect tube M1 and the fifth resistor R5.

[0103] The source of the first field effect tube M1 and the first end of the fifth resistor R5 are connected and jointly constitute the input end of the switch circuit 01, and are connected with the sampling circuit 02 to access the power supply direct current VCC and output the source voltage of the first field effect tube M1; the drain of the first field effect tube M1 constitutes the input end of the switch circuit 01, and is connected with the sampling circuit 02 to output the power supply direct current VCC and output the drain voltage of the first field effect tube M1; the gate of the first field effect tube M1 and the second end of the fifth resistor R5 are connected and jointly constitute the control end of the switch circuit 01, and are connected with the control circuit 03 to access the control signal.

[0104] The switch circuit 01 is simple and reliable.

[0105] The working principle will be further described below in combination with Figure 4 to Figure 5 .

[0106] In Figure 4 and Figure 5 , the second general input and output end P1.1 of the microprocessor U4 outputs the control signal.

[0107] In Figure 4 , the first field effect tube M1 is turned on based on the control signal (low level) and transmits the power supply direct current VCC.

[0108] In Figure 5 , the second field effect tube M2 is turned on based on the control signal (high level), the first field effect tube M1 is turned on and transmits the power supply direct current VCC.

[0109] In Figure 4 andFigure 5 In the specific implementation process, the first follower 021 comprising the first operational amplifier U1 and the first resistor R1 follows the source voltage of the first field effect tube to output the first voltage; the second follower 022 comprising the second operational amplifier U2 and the second resistor R2 follows the drain voltage of the first field effect tube to output the second voltage; the third operational amplifier U3 performs subtraction operation according to the second voltage and the first voltage to output the sampling signal to the first general input and output terminal P1.0 of the microprocessor U4; the temperature detection circuit 04 detects the temperature to output the temperature detection signal; and the microprocessor U4 obtains the current value according to the temperature detection signal and the sampling signal.

[0110] The utility model embodiment further provides an electronic device, and the electronic device comprises the current detection circuit.

[0111] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the application.

[0112] The above-described embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A current detection circuit, characterized by, The switching circuit, the sampling circuit and the control circuit are included. The switching circuit includes a first field effect transistor connected in series on a power supply main circuit; The switching circuit is used for transmitting power supply direct current through the first field effect transistor in response to a control signal; The sampling circuit is connected with the switching circuit and is used for sampling current flowing through the first field effect transistor to output a sampling signal; The control circuit is connected with the switching circuit and the sampling circuit and is used for outputting a control signal and obtaining a current value according to the sampling signal.

2. The current sense circuit of claim 1, wherein, Further comprising: A temperature detection circuit is used for detecting temperature to output a temperature detection signal; The control circuit is specifically used for outputting a control signal and obtaining a current value according to the temperature detection signal and the sampling signal.

3. The current sense circuit of claim 1, wherein, The sampling circuit includes: A first follower connected with a source of the first field effect transistor and used for following a source voltage of the first field effect transistor to output a first voltage; A second follower connected with a drain of the first field effect transistor and used for following a drain voltage of the first field effect transistor to output a second voltage; A subtracter connected with the first follower, the second follower and the control circuit and used for subtracting the second voltage from the first voltage to output a sampling signal.

4. The current sense circuit of claim 3, wherein, The first follower includes a first operational amplifier and a first resistor; A non-inverting input terminal of the first operational amplifier constitutes an input terminal of the first follower and is connected with the source of the first field effect transistor to access the source voltage of the first field effect transistor; An output terminal of the first operational amplifier and a first terminal of the first resistor are connected and jointly constitute an output terminal of the first follower and are connected with the subtracter to output the first voltage; An inverting input terminal of the first operational amplifier is connected with a second terminal of the first resistor.

5. The current sense circuit of claim 3, wherein, The second follower includes a second operational amplifier and a second resistor; A non-inverting input terminal of the second operational amplifier constitutes an input terminal of the second follower and is connected with the drain of the first field effect transistor to access the drain voltage of the first field effect transistor; An output terminal of the second operational amplifier and a first terminal of the second resistor are connected and jointly constitute an output terminal of the second follower and are connected with the subtracter to output the second voltage; An inverting input terminal of the second operational amplifier is connected with a second terminal of the second resistor.

6. The current sense circuit of claim 3, wherein, The subtracter includes a third operational amplifier, a third resistor and a fourth resistor; A non-inverting input terminal of the third operational amplifier constitutes a first input terminal of the subtracter and is connected with the second follower to access the second voltage; A first terminal of the third resistor constitutes a second input terminal of the subtracter and is connected with the first follower to access the first voltage; A second terminal of the third resistor and a first terminal of the fourth resistor and an inverting input terminal of the third operational amplifier are connected; An output terminal of the third operational amplifier and a second terminal of the fourth resistor are connected and jointly constitute an output terminal of the subtracter and are connected with the control circuit to output the sampling signal.

7. The current sense circuit of claim 1, wherein, The switch circuit comprises the first field effect transistor, the second field effect transistor, the third field effect transistor, the voltage stabilizer, the sixth resistor, the seventh resistor, the eighth resistor and the ninth resistor; The first end of the seventh resistor constitutes a control end of the switch circuit, and is connected with the control circuit to access the control signal; The source of the first field effect transistor and the negative electrode of the voltage stabilizer are connected and jointly constitute an input end of the switch circuit, and are connected with the sampling circuit to access the power supply direct current and output the source voltage of the first field effect transistor; The drain of the first field effect transistor and the first end of the ninth resistor are connected and constitute an input end of the switch circuit, and are connected with the sampling circuit to output the power supply direct current and output the drain voltage of the first field effect transistor; The second end of the seventh resistor is connected with the gate of the second field effect transistor and the first end of the eighth resistor, the drain of the second field effect transistor is connected with the first end of the sixth resistor and the gate of the third field effect transistor, the drain of the third field effect transistor is connected with the second end of the ninth resistor, the second end of the sixth resistor is connected with the positive electrode of the voltage stabilizer and the gate of the first field effect transistor, and the source of the second field effect transistor, the second end of the eighth resistor and the source of the third field effect transistor are commonly connected to a power supply ground.

8. The current sense circuit of claim 1, wherein, The switch circuit comprises the first field effect transistor and the fifth resistor; The source of the first field effect transistor and the first end of the fifth resistor are connected and jointly constitute an input end of the switch circuit, and are connected with the sampling circuit to access the power supply direct current and output the source voltage of the first field effect transistor; The drain of the first field effect transistor constitutes an input end of the switch circuit, and is connected with the sampling circuit to output the power supply direct current and output the drain voltage of the first field effect transistor; The gate of the first field effect transistor and the second end of the fifth resistor are connected and jointly constitute a control end of the switch circuit, and are connected with the control circuit to access the control signal.

9. The current sense circuit of claim 1, wherein, The control circuit comprises a microprocessor; The first general input and output end of the microprocessor constitutes a sampling signal input end of the control circuit, and is connected with the sampling circuit to access the sampling signal; The second general input and output end of the microprocessor constitutes a control signal output end of the control circuit, and is connected with the switch circuit to output the switch signal.

10. An electronic device, comprising: The electronic device comprises the current detection circuit according to any one of claims 1 to 9.

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