Negative voltage current detection circuit
By designing a negative voltage current detection circuit, including a voltage conversion module, a sampling module and a sampling current output module, the effective sampling of the negative voltage current under the free-current attenuation state of the stepper motor is achieved, and the problem of failure of the sampling circuit in the prior art is solved. , ensuring the stability of the motor driving process.
Patent Information
- Application Number
- CN202411297665.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-01-17
AI Technical Summary
The prior art cannot effectively detect negative voltage current when the stepper motor is in a free-current attenuation state, resulting in failure of the sampling circuit.
A negative voltage current detection circuit is designed, including a voltage conversion module, a sampling module and a sampling current output module. By converting the load voltage of the power tube into a sampling voltage that can be used for sampling, and copying the load current into a sampling current in proportion. Mirror output to achieve sampling of negative voltage current.
The negative voltage current can be effectively sampled when the motor is in the free-current attenuation state, which solves the problem of sampling circuit failure and ensures the stability of the motor driving process.
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Figure CN119322193A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of motor drive technology, and in particular to a negative voltage current detection circuit. Background Art
[0002] Common stepper motor single coil full-bridge drive circuit model such as Figure 1 As shown, Figure 1 As a background technology, a schematic diagram of a stepper motor drive circuit is shown. AH, AL, BH, and BL are four power tubes, and M is a stepper motor. Taking this as an example, first, when the two power tubes AH and BL are turned on, the current flows from VM through the two power tubes AH and BL from left to right to the ground. At this time, it is in the motor drive DRIVE stage; when the current flowing through the motor reaches a preset value, the two power tubes AH and BL are turned off, and the motor enters a freewheeling attenuation state (because the internal coil of the motor has an inductance effect, which will cause the current to continue to flow from left to right and continue to decay).
[0003] There are two ways of current decay: asynchronous decay and synchronous decay. Asynchronous decay is when the decay current flows through the body diode of the power tube, and the current direction is still from left to right; synchronous decay is when the diagonally opposite BH and AL power tubes are turned on, so that the decay current flows through the power tube, and the current direction is still from left to right. The following mainly uses synchronous decay to explain.
[0004] There are generally three current decay modes: slow decay, fast decay, and mixed decay. Slow decay is when the motor enters the freewheeling decay state, turning on the AL and BL power tubes, and the current direction is as follows: Figure 1 As shown in (b); fast decay is when the motor enters the freewheeling decay state, the AL and BH power tubes are turned on, and the current direction is as follows Figure 1 As shown in (c); mixed decay is a combination of fast and slow decay.
[0005] When the motor is in the freewheeling attenuation state, the voltage output is negative voltage, and the operational amplifier cannot output normally. At this time, the sampling circuit fails. Therefore, there is an urgent need for a detection circuit that can sample and detect negative voltage current. Summary of the invention
[0006] The purpose of the present application is to provide a negative voltage current detection circuit, which can sample the negative voltage current when the motor is in a freewheeling attenuation state.
[0007] The embodiment of the present application is implemented as follows:
[0008] According to one aspect of an embodiment of the present application, a negative voltage current detection circuit is provided, comprising: a voltage conversion module, a sampling module and a sampling current output module; the voltage conversion module is connected to a reference voltage source, a power tube, the sampling module and the sampling current output module, and is used to convert the load voltage of the power tube into a sampling voltage that can be used for sampling; the sampling module is used to proportionally copy the load current of the power tube, and output a sampling current proportional to the load current to the sampling current output module; the sampling current output module is used to mirror the sampling current and output it.
[0009] Optionally, the voltage conversion module includes a first conversion module, a second conversion module and a third conversion module; the input end of the first conversion module is connected to the reference voltage source and the power tube, and the other end is connected to the second conversion module, for calculating the relationship between the output voltage and the reference voltage output by the reference voltage source; the second conversion module is also connected to the reference voltage source and the third conversion module, for eliminating the influence of the reference voltage on the output voltage; the third conversion module is also connected to the sampling module and the sampling current module, for using the converted output voltage as the sampling voltage.
[0010] Optionally, the first conversion module includes a first operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor; one end of the first resistor is connected to the power tube, and the other end is connected to the negative input terminal of the first operational amplifier; one end of the second resistor is connected to the negative input terminal of the first operational amplifier, and the other end is connected to the output terminal of the first operational amplifier; one end of the third resistor is connected to the reference voltage source, and the other end is connected to the positive input terminal of the first operational amplifier; one end of the fourth resistor is connected to the positive input terminal of the first operational amplifier, and the other end is grounded; the output terminal of the first operational amplifier is also connected to the second conversion module.
[0011] Optionally, the second conversion module includes a second operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor; one end of the fifth resistor is connected to the output of the first operational amplifier, and the other end is connected to the positive input of the second operational amplifier; one end of the sixth resistor is grounded, and the other end is connected to the positive input of the second operational amplifier; one end of the seventh resistor is connected to the reference voltage source, and the other end is connected to the negative input of the second operational amplifier; one end of the eighth resistor is connected to the negative input of the second operational amplifier, and the other end is connected to the output of the second operational amplifier; the output of the second operational amplifier is also connected to the third conversion module.
[0012] Optionally, the third conversion module includes a third operational amplifier and an amplifier tube; the positive input terminal of the third operational amplifier is connected to the output terminal of the second operational amplifier, the negative input terminal is connected to the source of the amplifier tube, and the output terminal of the third operational amplifier is connected to the gate of the amplifier tube; the drain of the amplifier tube is connected to the sampling current output module, and the source is connected to the sampling module.
[0013] Optionally, the sampling module includes a sampling tube; the gate of the sampling tube is connected to the gate of the power tube, the source is grounded, and the drain is connected to the voltage conversion module.
[0014] Optionally, the sampling current output module includes a first mirror tube and a second mirror tube; the gate of the first mirror tube is connected to the gate of the second mirror tube and the drain of the first mirror tube, the source of the first mirror tube is connected to the source of the second mirror tube; the drain of the second mirror tube is connected to the sampling current output end.
[0015] Optionally, the voltage conversion module includes a fourth conversion module and a third conversion module; the fourth conversion module includes a first operational amplifier, a first resistor, a second resistor and a third resistor, one end of the first resistor is linked to the power tube, and the other end is connected to the negative input end of the fourth operational amplifier, one end of the second resistor is connected to the negative input end of the fourth amplifier, and the other end is connected to the output end of the fourth operational amplifier; the third conversion module includes a third operational amplifier and an amplifier tube, the positive input end of the third operational amplifier is connected to the output end of the second operational amplifier, the negative input end is connected to the source of the amplifier tube, and the output end of the third operational amplifier is connected to the gate of the amplifier tube; the drain of the amplifier tube is connected to the sampling current output module, and the source is connected to the sampling module.
[0016] Optionally, the resistance value of the first resistor, the resistance value of the second resistor, the resistance value of the third resistor and the resistance value of the fourth resistor are equal.
[0017] Optionally, the resistance value of the fifth resistor, the resistance value of the sixth resistor, the resistance value of the seventh resistor and the resistance value of the eighth resistor are equal.
[0018] The beneficial effects of the embodiments of the present application include:
[0019] A negative voltage detection circuit provided in an embodiment of the present application includes: a voltage conversion module, a sampling module and a sampling current output module; the voltage conversion module is connected to a reference voltage source, a power tube, the sampling module and the sampling current output module, and is used to convert the load voltage of the power tube into a sampling voltage that can be used for sampling; the sampling module is used to proportionally copy the load current of the power tube, and output a sampling current proportional to the load current to the sampling current output module; the sampling current output module is used to mirror the sampling current to output the sampling current, so as to sample the negative voltage current when the motor is in a freewheeling attenuation state. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0021] Figure 1 The following is a schematic diagram of a stepper motor driving circuit of the background technology;
[0022] Figure 2 It is a structural schematic diagram of a current sampling circuit in the prior art;
[0023] Figure 3 This is a schematic diagram of the structure of the negative pressure current detection circuit in the embodiment of the present application;
[0024] Figure 4 This is a structural schematic diagram of a negative pressure current detection module in another embodiment of the present application;
[0025] Figure 5 This is a schematic diagram of the structure of the negative pressure current detection module in the third embodiment of the present application. DETAILED DESCRIPTION
[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.
[0027] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.
[0028] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.
[0029] In the description of the present application, it should be noted that the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.
[0030] Current sampling in the prior art usually consists of a sampling tube, a sampling operational amplifier and an amplifier tube. Figure 2 FIG. 1 is a schematic diagram of a current sampling circuit in the prior art. Figure 2 In the figure, the sampling tube M1 and the power tube M are the same type of devices, with the same L value and proportional W value; the two inputs of the sampling operational amplifier are connected to the drain terminals of the sampling tube M1 and the power tube M0 respectively, and the output is connected to the gate terminal of the amplifier tube M2. M3 and M4 are mirror tubes, which mirror the sampling current ISENSE to output.
[0031] When the motor works in the DRVIE stage, according to the current formula of the MOS tube:
[0032]
[0033] μ n is the carrier mobility, C OX is the gate oxide capacitance per unit area. The gates of the power tube M0 and the sampling tube M1 are connected together. The sources of the power tube M0 and the sampling tube M1 are both grounded. Then V GS0 =V GS1 ; The power tube M0 and the sampling tube M1 are of the same type, then μ n , C OX With V TH The drains of the power tube M0 and the sampling tube M1 are connected to the two input ports of the sampling operational amplifier. According to the properties of the operational amplifier, when the gain is large enough, the two input voltages are the same, then V DS1 =V DS2 ; The L value set for the power tube M0 and the sampling tube M1 is the same, W0 / W1=K. According to the current formula, when the power tube works normally, 1 / K of the power tube current will flow through the sampling tube to achieve current sampling.
[0034] When the motor is in the freewheeling attenuation state, the current flows from the ground to VOUT. At this time, VOUT is a negative voltage, the operational amplifier cannot output normally, the amplifier tube M2 loses its source following ability, and the sampling circuit fails.
[0035] According to one aspect of an embodiment of the present application, a negative voltage current detection circuit is provided, comprising: a voltage conversion module, a sampling module and a sampling current output module; the voltage conversion module is connected to a reference voltage source, a power tube, the sampling module and the sampling current output module, and is used to convert the load voltage of the power tube into a sampling voltage that can be used for sampling; the sampling module is used to proportionally copy the load current of the power tube, and output a sampling current proportional to the load current to the sampling current output module; the sampling current output module is used to mirror the sampling current and output it.
[0036] like Figure 3 As shown, Figure 3 The present invention is a schematic diagram of the structure of the negative voltage current detection circuit in the embodiment of the present application. In the embodiment of the present application, a voltage conversion module, a sampling module and a sampling current output module are formed, wherein the voltage conversion module is connected to a reference voltage source, a power tube, the sampling module and the sampling current output module, and a reference voltage for calculation is obtained through the reference voltage source, and a voltage to be converted for conversion is obtained through the power tube. In some embodiments, the voltage value of the voltage to be converted is a negative value, and the working property of the voltage conversion module is to convert the negative voltage output by the power tube into a positive voltage. At this time, the voltage difference at both ends of the sampling module is equal to the voltage difference at both ends of the power tube, and the current flowing through the sampling module is proportional to the current flowing through the power tube, and then the current flowing through the sampling current output module is the sampling current.
[0037] Optionally, the voltage conversion module includes a first conversion module, a second conversion module and a third conversion module; the input end of the first conversion module is connected to the reference voltage source and the power tube, and the other end is connected to the second conversion module, for calculating the relationship between the output voltage and the reference voltage output by the reference voltage source; the second conversion module is also connected to the reference voltage source and the third conversion module, for eliminating the influence of the reference voltage on the output voltage; the third conversion module is also connected to the sampling module and the sampling current module, for using the converted output voltage as the sampling voltage.
[0038] In this embodiment, if Figure 4 As shown, Figure 4This is a schematic diagram of the structure of the negative voltage current detection module in another embodiment of the present application. The voltage conversion module is divided into three parts, wherein the first conversion module is connected to the reference voltage source and the power tube, and is used to calculate the relationship between the output voltage and the reference voltage, and the output result is the first output voltage. The second conversion module receives the output result of the first conversion module, and then calculates through the reference voltage to obtain the second output voltage after removing the reference voltage. The third conversion module uses the second output voltage as the sampling voltage of the sampling module, and is used for the sampling tube to sample the current of the power tube.
[0039] Optionally, the first conversion module includes a first operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor; one end of the first resistor is connected to the power tube, and the other end is connected to the negative input terminal of the first operational amplifier; one end of the second resistor is connected to the negative input terminal of the first operational amplifier, and the other end is connected to the output terminal of the first operational amplifier; one end of the third resistor is connected to the reference voltage source, and the other end is connected to the positive input terminal of the first operational amplifier; one end of the fourth resistor is connected to the positive input terminal of the first operational amplifier, and the other end is grounded; the output terminal of the first operational amplifier is also connected to the second conversion module.
[0040] In this embodiment, the first conversion module includes a first operational amplifier and a first resistor to a fourth resistor, a total of four voltage-dividing resistors. The positive input terminal of the first operational amplifier is the B terminal, the negative input terminal is the A terminal, and the output is the VOUT1 terminal. It can be seen from the properties of the operational amplifier that:
[0041]
[0042]
[0043] When R1=R2=R3=R4, VOUT1=VREF-VOUT, where R1 is the resistance of the first resistor, R2 is the resistance of the second resistor, R3 is the resistance of the third resistor, R4 is the resistance of the fourth resistor, VOUT is the output voltage of the power tube, and VREF is the reference voltage. Based on this, the relationship between the output voltage and the reference voltage can be obtained, and VOUT1 is the first output voltage.
[0044] Optionally, the second conversion module includes a second operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor; one end of the fifth resistor is connected to the output of the first operational amplifier, and the other end is connected to the positive input of the second operational amplifier; one end of the sixth resistor is grounded, and the other end is connected to the positive input of the second operational amplifier; one end of the seventh resistor is connected to the reference voltage source, and the other end is connected to the negative input of the second operational amplifier; one end of the eighth resistor is connected to the negative input of the second operational amplifier, and the other end is connected to the output of the second operational amplifier; the output of the second operational amplifier is also connected to the third conversion module.
[0045] It is easy to understand that the fifth resistor, the sixth resistor, the seventh resistor and the eighth resistor are voltage-dividing resistors. When R5=R6=R7=R8, VOUT2=VREF-(VREF-VOUT)=-VOUT, wherein R5 is the resistance value of the fifth resistor, R6 is the resistance value of the sixth resistor, R7 is the resistance value of the seventh resistor, R8 is the resistance value of the eighth resistor, and VOUT is the output voltage of the power tube. Based on this, the influence of the reference voltage can be removed to obtain a second output voltage without a reference voltage, namely VOUT2. At this time, VOUT2=-VOUT, and the negative output voltage is converted into a positive value.
[0046] Optionally, the third conversion module includes a third operational amplifier and an amplifier tube M2; the positive input terminal of the third operational amplifier is connected to the output terminal of the second operational amplifier, the negative input terminal is connected to the source of the amplifier tube M2, and the output terminal of the third operational amplifier is connected to the gate of the amplifier tube M2; the drain of the amplifier tube M2 is connected to the sampling current output module, and the source is connected to the sampling module.
[0047] In this embodiment, the third conversion module includes a third operational amplifier and an amplifier tube M2, and the amplifier tube M2 is also connected to the sampling module and the sampling current output module. Through the principle of the operational amplifier, the voltage of the negative input terminal of the third operational amplifier is the same as the voltage of the positive input terminal, that is, V G =VOUT2=-VOUT. At this time, the voltage difference across the sampling module is VOUT, and the voltage difference across the power tube is also VOUT. The gate of the MOS tube in the sampling module is connected to the gate of the power tube, so the gate of the MOS tube in the sampling module is proportional to the current flowing through the power tube. The current obtained through the sampling current output module is the sampling current.
[0048] Optionally, the sampling module includes a sampling tube; the gate of the sampling tube is connected to the gate of the power tube, the source is grounded, and the drain is connected to the voltage conversion module.
[0049] In this embodiment, the MOS tube in the sampling module is the sampling tube, and the gate of the sampling tube is connected to the gate of the power tube to ensure that the current flowing through the sampling tube is proportional to the current flowing through the power tube.
[0050] Optionally, the sampling current output module includes a first mirror tube and a second mirror tube; the gate of the first mirror tube is connected to the gate of the second mirror tube and the drain of the first mirror tube, the source of the first mirror tube is connected to the source of the second mirror tube; the drain of the second mirror tube is connected to the sampling current output end.
[0051] In this embodiment, the first mirror tube is an M3 tube, and the second mirror tube is an M4 tube. The first mirror tube and the second mirror tube form a current mirror. Based on the first mirror tube and the second mirror tube, the sampling current flowing through the sampling tube can be viewed at the drain of the second mirror tube as the output end.
[0052] Optionally, the voltage conversion module includes a fourth conversion module and a third conversion module; the fourth conversion module includes a first operational amplifier, a first resistor, a second resistor and a third resistor, one end of the first resistor is linked to the power tube, and the other end is connected to the negative input end of the fourth operational amplifier, one end of the second resistor is connected to the negative input end of the fourth amplifier, and the other end is connected to the output end of the fourth operational amplifier; the third conversion module includes a third operational amplifier and an amplifier tube M2, the positive input end of the third operational amplifier is connected to the output end of the second operational amplifier, the negative input end is connected to the source of the amplifier tube M2, and the output end of the third operational amplifier is connected to the gate of the amplifier tube M2; the drain of the amplifier tube M2 is connected to the sampling current output module, and the source is connected to the sampling module.
[0053] In this embodiment, if the reference voltage is directly grounded and the voltage of the reference voltage is 0V, the voltage conversion module may be the fourth conversion module and the third conversion module. At this time, based on the structure of the fourth conversion module, it can be obtained that:
[0054] VA=VB=0V
[0055] (VOUT4-VOUT) / (R1+R2)=(0-VOUT) / R1
[0056] When the first resistor is equal to the second resistor, VOUT4=-VOUT, and through the operational amplifier A2, it can be obtained that: VG=VOUT4=-VOUT. At this time, the voltage difference between the power tube M0 and the sampling tube M1 is VOUT, and the gate of the sampling tube is connected to the gate of the power tube, so the gate potential of the sampling tube is the same as the gate potential of the power tube. At this time, according to the circuit formula, the current flowing through the sampling tube is proportional to the current flowing through the power tube; the current ISENSE obtained through the mirror tubes M3 and M4 is the sampling current.
[0057] Optionally, the resistance value of the first resistor, the resistance value of the second resistor, the resistance value of the third resistor and the resistance value of the fourth resistor are equal.
[0058] Optionally, the resistance value of the fifth resistor, the resistance value of the sixth resistor, the resistance value of the seventh resistor and the resistance value of the eighth resistor are equal.
[0059] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.
[0060] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
[0061] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.
[0062] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A negative voltage current detection circuit, characterized in that: include: Voltage conversion module, sampling module and sampling current output module; The voltage conversion module is connected to the reference voltage source, the power tube, the sampling module and the sampling current output module, and is used to convert the load voltage of the power tube into a sampling voltage that can be used for sampling; The sampling module is used to proportionally copy the load current of the power tube and output a sampling current proportional to the load current to the sampling current output module; The sampling current output module is used for mirroring and outputting the sampling current.
2. The negative voltage current detection circuit according to claim 1, characterized in that: The voltage conversion module includes a first conversion module, a second conversion module and a third conversion module; The input end of the first conversion module is connected to the reference voltage source and the power tube, and the other end is connected to the second conversion module, and is used to calculate the relationship between the output voltage and the reference voltage output by the reference voltage source; The second conversion module is also connected to the reference voltage source and the third conversion module, and is used to eliminate the influence of the reference voltage on the output voltage; The third conversion module is also connected to the sampling module and the sampling current module, and is used to use the converted output voltage as the sampling voltage.
3. The negative voltage current detection circuit according to claim 2, characterized in that: The first conversion module includes a first operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor; One end of the first resistor is connected to the power tube, and the other end is connected to the negative input terminal of the first operational amplifier; One end of the second resistor is connected to the negative input terminal of the first operational amplifier, and the other end is connected to the output terminal of the first operational amplifier; One end of the third resistor is connected to the reference voltage source, and the other end is connected to the positive input terminal of the first operational amplifier; One end of the fourth resistor is connected to the positive input terminal of the first operational amplifier, and the other end is grounded; The output end of the first operational amplifier is also connected to the second conversion module.
4. The negative voltage current detection circuit according to claim 2, characterized in that: The second conversion module includes a second operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor; One end of the fifth resistor is connected to the output end of the first operational amplifier, and the other end is connected to the positive input end of the second operational amplifier; One end of the sixth resistor is grounded, and the other end is connected to the positive input terminal of the second operational amplifier; One end of the seventh resistor is connected to the reference voltage source, and the other end is connected to the negative input terminal of the second operational amplifier; One end of the eighth resistor is connected to the negative input terminal of the second operational amplifier, and the other end is connected to the output terminal of the second operational amplifier; The output terminal of the second operational amplifier is also connected to the third conversion module.
5. The negative voltage current detection circuit according to claim 2, characterized in that: The third conversion module includes a third operational amplifier and an amplifier tube; The positive input terminal of the third operational amplifier is connected to the output terminal of the second operational amplifier, the negative input terminal is connected to the source of the amplifier tube, and the output terminal of the third operational amplifier is connected to the gate of the amplifier tube; The drain of the amplifier tube is connected to the sampling current output module, and the source is connected to the sampling module.
6. The negative voltage current detection circuit according to claim 1, characterized in that: The sampling module includes a sampling tube; The gate of the sampling tube is connected to the gate of the power tube, the source is grounded, and the drain is connected to the voltage conversion module.
7. The negative voltage current detection circuit according to claim 1, characterized in that: The sampling current output module includes a first mirror tube and a second mirror tube; The gate of the first mirror tube is connected to the gate of the second mirror tube and the drain of the first mirror tube, and the source of the first mirror tube is connected to the source of the second mirror tube; The drain of the second mirror tube is connected to the sampling current output terminal.
8. The negative voltage current detection circuit according to claim 1, characterized in that: The voltage conversion module includes a fourth conversion module and a third conversion module; The fourth conversion module comprises a first operational amplifier, a first resistor, a second resistor and a third resistor, one end of the first resistor is connected to the power tube, and the other end is connected to the negative input end of the fourth operational amplifier, one end of the second resistor is connected to the negative input end of the fourth amplifier, and the other end is connected to the output end of the fourth operational amplifier; The third conversion module includes a third operational amplifier and an amplifier tube, wherein the positive input terminal of the third operational amplifier is connected to the output terminal of the second operational amplifier, the negative input terminal is connected to the source of the amplifier tube, and the output terminal of the third operational amplifier is connected to the gate of the amplifier tube; The drain of the amplifier tube is connected to the sampling current output module, and the source is connected to the sampling module.
9. The negative voltage current detection circuit according to claim 3, characterized in that: The resistance value of the first resistor, the resistance value of the second resistor, the resistance value of the third resistor and the resistance value of the fourth resistor are equal.
10. The negative voltage current detection circuit according to claim 4, characterized in that: The resistance value of the fifth resistor, the resistance value of the sixth resistor, the resistance value of the seventh resistor and the resistance value of the eighth resistor are equal.