Isolation current sampling circuit

Abstract

The utility model discloses an isolation current sampling circuit, comprising an isolation front end power supply module used for providing voltage for a post-stage load and an isolation operational amplifier module, and collecting the input current of the load through a sampling resistor, the sampling resistor transmitting a voltage differential signal to the isolation operational amplifier module; the isolation operational amplifier module is used for converting the voltage differential signal into a voltage small signal of which the voltage value is in one-to-one correspondence with the voltage difference of the voltage differential signal, and transmitting the voltage small signal to the secondary operational amplifier module; the secondary operational amplifier module is used for carrying out signal amplification on the small voltage signal according to a preset amplification factor so as to obtain an amplified voltage signal; and the control module is used for converting the amplified voltage signal into a corresponding current value so as to obtain the current value of the power supply inlet. According to the isolation current sampling circuit, the front-end voltage and the rear-stage circuit are effectively isolated, the reliability and safety of a system are improved, and the noise and interference resistance of the system is enhanced.

Description

Technical Field

[0001] The utility model relates to the technical field of current sampling, in particular to an isolated current sampling circuit. Background Art

[0002] In today's society, with the continuous progress of technology, the power system pays more and more attention to energy conservation and consumption reduction. Among them, the importance of current monitoring is becoming increasingly prominent. Therefore, the current sampling circuit has a very wide application prospect and is of great significance to promoting the development of related fields. However, the current isolated current sampling circuit has certain limitations and problems such as inaccurate precision. For example, the operation of the isolation operational amplifier requires a stable power supply. Therefore, the instability of the power supply voltage may lead to inaccurate current sampling accuracy. The accuracy and temperature drift of the sampling resistor will also affect the final accuracy result. Summary of the Utility Model

[0003] In order to solve the technical problems in the background art, the utility model proposes an isolated current sampling circuit.

[0004] An isolated current sampling circuit proposed by the utility model includes:

[0005] An isolated front-end power supply module, which is used to provide voltage for the subsequent load and the isolation operational amplifier module, and at the same time collect the input current of the load through a sampling resistor. The sampling resistor converts the collected input current into a voltage differential signal and transmits the voltage differential signal to the isolation operational amplifier module;

[0006] An isolation operational amplifier module, which is used to convert the voltage differential signal into a small voltage signal whose voltage value corresponds one-to-one to the voltage difference of the voltage differential signal, and transmit the small voltage signal to the secondary operational amplifier module;

[0007] A secondary operational amplifier module, which is used to amplify the small voltage signal according to a preset amplification factor to obtain an amplified voltage signal, and the amplified voltage signal;

[0008] A control module, which is used to convert the amplified voltage signal into a corresponding current value to obtain the current value at the power supply inlet;

[0009] Wherein, the isolated front-end power supply module is electrically connected to the input end of the isolation operational amplifier module through a sampling resistor, the output end of the isolation operational amplifier module is electrically connected to the input end of the secondary operational amplifier module, and the output end of the secondary operational amplifier module is electrically connected to the input end of the control module.

[0010] Preferably, the isolated operational amplifier module specifically includes an isolated operational amplifier U6, a resistor R7, a resistor R11, a resistor R12, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, and a capacitor C10; the INP terminal of the isolated operational amplifier U6 is electrically connected to one end of the capacitor C10, the other end of the capacitor C10 is electrically connected to the INN terminal of the isolated operational amplifier U6, the other end of the capacitor C10 is electrically connected to one end of the resistor R11, the other end of the resistor R11 is grounded to GND1, one end of the capacitor C10 is electrically connected to one end of the resistor R7, the other end of the resistor R7 is grounded to GND2, the GUD1 terminal of the isolated operational amplifier U6 is grounded to GUD1, the GUD2 terminal of the isolated operational amplifier U6 is grounded to GUD2, the REFIN terminal of the isolated operational amplifier U6 is electrically connected to one end of the resistor R12, the other end of the resistor R12 is grounded to GND2, the VDD1 terminal of the isolated operational amplifier U6 is electrically connected to one end of the capacitor C5, the VDD1 terminal of the isolated operational amplifier U6 is electrically connected to one end of the capacitor C8, the other end of the capacitor C8 and the other end of the capacitor C5 are commonly grounded to GUD1, one end of the capacitor C5 is electrically connected to the 5V power supply, the VDD2 terminal of the isolated operational amplifier U6 is electrically connected to one end of the capacitor C6, the VDD2 terminal of the isolated operational amplifier U6 is electrically connected to one end of the capacitor C6, the other end of the capacitor C6 and the other end of the capacitor C7 are commonly grounded to GUD1, one end of the capacitor C6 is electrically connected to the 5V power supply, the OUT terminal of the isolated operational amplifier U6 is electrically connected to the input terminal of the secondary operational amplifier module, and the voltage differential signal is connected to the INP terminal and the INN terminal of the isolated operational amplifier U6 through the resistors R7 and R11.

[0011] Preferably, the isolated front-end power supply module specifically includes: a capacitor C1, a capacitor C4, a resistor R5, an anti-reverse diode D1, an electrolytic capacitor C2, a capacitor C3, a bidirectional TVS diode D2, and a fuse FU1. One end of the capacitor C1 is electrically connected to one end of the capacitor C4, the other end of the capacitor C4 is grounded to GND1, one end of the capacitor C1 is grounded to EGND, the other end of the capacitor C1 is electrically connected to one end of the fuse FU1, one end of the fuse FU1 is electrically connected to one end of the bidirectional TVS diode D2, the other end of the bidirectional TVS diode D2 is electrically connected to the other end of the capacitor C4, the other end of the fuse FU1 is electrically connected to the positive electrode of the anti-reverse diode D1, the negative electrode of the anti-reverse diode D1 is electrically connected to the positive electrode of the electrolytic capacitor C1, the negative electrode of the electrolytic capacitor C1 is electrically connected to one end of the resistor R5, the other end of the resistor R5 is grounded to GND1, the negative electrode of the electrolytic capacitor C1 is electrically connected to one end of the capacitor C3, the positive electrode of the electrolytic capacitor C1 is electrically connected to the other end of the capacitor C3, the negative electrode of the electrolytic capacitor C1 is grounded to GND2, the positive electrode of the electrolytic capacitor C1 is electrically connected to the load, and one end of the capacitor C1 is connected to the power supply V_IN+ terminal.

[0012] Preferably, the resistor R5 is a sampling resistor, and the voltage differential signal is taken out from both ends of the resistor R5.

[0013] Preferably, the secondary operational amplifier module specifically includes: operational amplifier U7A, capacitor C9, resistor R6, resistor R8, resistor R10, operational amplifier U7B, resistor R9, capacitor C11, diode D3, diode D4; the negative input terminal of operational amplifier U7A is electrically connected to one end of R8, the other end of R8 is grounded, one end of R8 is electrically connected to one end of resistor R6, the other end of resistor R6 is electrically connected to the output terminal of operational amplifier U7A, the positive input terminal of operational amplifier U7A is electrically connected to one end of resistor R10, the other end of resistor R10 is electrically connected to the output terminal of the isolation operational amplifier module; the positive power supply terminal of operational amplifier U7A is connected to a 3V power supply, the positive power supply terminal of operational amplifier U7A is electrically connected to one end of capacitor C9, the other end of capacitor C9 is grounded to GND2, the negative power supply terminal of operational amplifier U7A is grounded to GND2; the output terminal of operational amplifier U7A is electrically connected to the positive input terminal of operational amplifier U7B, the output terminal of operational amplifier U7B is electrically connected to one end of resistor R9, the other end of resistor R9 is electrically connected to one end of capacitor C11, the negative input terminal of operational amplifier U7B is electrically connected to one end of resistor R9, the other end of capacitor C11 is grounded, one end of capacitor C11 is electrically connected to the negative electrode of diode D3, the positive electrode of diode D3 is grounded to GND2, one end of capacitor C11 is electrically connected to the positive electrode of diode D4, the negative electrode of diode D4 is electrically connected to the power supply terminal, and one end of capacitor C11 is electrically connected to the control module.

[0014] Preferably, the control module is specifically an MCU module, the input terminal of the MCU module is electrically connected to the control terminal, and the output terminal of the secondary operational amplifier module is electrically connected to the input terminal of the MCU module.

[0015] In the present invention, for the proposed isolation current sampling circuit, the isolation operational amplifier module converts the current sampling signal at the isolation front end into an isolated single-ended small voltage signal, and then connects to the MCU through the secondary operational amplifier module for acquisition to achieve the acquisition of the front-end current. This circuit effectively isolates the front-end voltage from the subsequent circuit, thereby improving the reliability and safety of the system and enhancing the system's resistance to noise and interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic circuit diagram of an isolation current sampling circuit proposed by the present invention;

[0017] Figure 2 is a schematic structural diagram of the isolation front-end power supply module of an isolation current sampling circuit proposed by the present invention;

[0018] Figure 3Schematic diagram of the combined structure of the isolation operational amplifier module and the secondary operational amplifier module of an isolation current sampling circuit proposed by the present utility model. Specific implementation mode

[0019] Refer to Figures 1 - 3 , an isolation current sampling circuit proposed by the present utility model includes:

[0020] An isolation front-end power supply module, which is used to provide voltage for the subsequent load and the isolation operational amplifier module, and at the same time collect the input current of the load through a sampling resistor. The input current collected by the sampling resistor is converted into a voltage differential signal, and the voltage differential signal is transmitted to the isolation operational amplifier module;

[0021] An isolation operational amplifier module, which is used to convert the voltage differential signal into a small voltage signal with a one-to-one correspondence between the voltage value and the voltage difference of the voltage differential signal, and transmit the small voltage signal to the secondary operational amplifier module;

[0022] A secondary operational amplifier module, which is used to amplify the small voltage signal by a preset amplification factor to obtain an amplified voltage signal, and the amplified voltage signal;

[0023] A control module, which is used to convert the amplified voltage signal into a corresponding current value to obtain the current value at the power supply inlet;

[0024] Among them, the isolation front-end power supply module is electrically connected to the input end of the isolation operational amplifier module through a sampling resistor, the output end of the isolation operational amplifier module is electrically connected to the input end of the secondary operational amplifier module, and the output end of the secondary operational amplifier module is electrically connected to the input end of the control module.

[0025] Specifically, such as Figure 1 and Figure 3As shown in the figure, the isolated operational amplifier module specifically includes an isolated operational amplifier U6, a resistor R7, a resistor R11, a resistor R12, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, and a capacitor C10. The INP terminal of the isolated operational amplifier U6 is electrically connected to one end of the capacitor C10, the other end of the capacitor C10 is electrically connected to the INN terminal of the isolated operational amplifier U6, the other end of the capacitor C10 is electrically connected to one end of the resistor R11, the other end of the resistor R11 is grounded to GND1, one end of the capacitor C10 is electrically connected to one end of the resistor R7, the other end of the resistor R7 is grounded to GND2, the GUD1 terminal of the isolated operational amplifier U6 is grounded to GUD1, the GUD2 terminal of the isolated operational amplifier U6 is grounded to GUD2, the REFIN terminal of the isolated operational amplifier U6 is electrically connected to one end of the resistor R12, the other end of the resistor R12 is grounded to GND2, the VDD1 terminal of the isolated operational amplifier U6 is electrically connected to one end of the capacitor C5, the VDD1 terminal of the isolated operational amplifier U6 is electrically connected to one end of the capacitor C8, the other end of the capacitor C8 and the other end of the capacitor C5 are commonly grounded to GUD1, one end of the capacitor C5 is electrically connected to the 5V power supply, the VDD2 terminal of the isolated operational amplifier U6 is electrically connected to one end of the capacitor C6, the VDD2 terminal of the isolated operational amplifier U6 is electrically connected to one end of the capacitor C6, the other end of the capacitor C6 and the other end of the capacitor C7 are commonly grounded to GUD1, one end of the capacitor C6 is electrically connected to the 5V power supply, the OUT terminal of the isolated operational amplifier U6 is electrically connected to the input terminal of the secondary operational amplifier module, and the voltage differential signal is connected to the INP terminal and the INN terminal of the isolated operational amplifier U6 through the resistors R7 and R11.

[0026] Specifically, as Figure 2 shown in the figure, the isolated front-end power supply module specifically includes: a capacitor C1, a capacitor C4, a resistor R5, an anti-reverse diode D1, an electrolytic capacitor C2, a capacitor C3, a bidirectional TVS diode D2, and a fuse FU1. One end of the capacitor C1 is electrically connected to one end of the capacitor C4, the other end of the capacitor C4 is grounded to GND1, one end of the capacitor C1 is grounded to EGND, the other end of the capacitor C1 is electrically connected to one end of the fuse FU1, one end of the fuse FU1 is electrically connected to one end of the bidirectional TVS diode D2, the other end of the bidirectional TVS diode D2 is electrically connected to the other end of the capacitor C4, the other end of the fuse FU1 is electrically connected to the positive electrode of the anti-reverse diode D1, the negative electrode of the anti-reverse diode D1 is electrically connected to the positive electrode of the electrolytic capacitor C1, the negative electrode of the electrolytic capacitor C1 is electrically connected to one end of the resistor R5, the other end of the resistor R5 is grounded to GND1, the negative electrode of the electrolytic capacitor C1 is electrically connected to one end of the capacitor C3, the positive electrode of the electrolytic capacitor C1 is electrically connected to the other end of the capacitor C3, the negative electrode of the electrolytic capacitor C1 is grounded to GND2, the positive electrode of the electrolytic capacitor C1 is electrically connected to the load, and one end of the capacitor C1 is connected to the power supply V_IN+ terminal.

[0027] Specifically, as shown in Figure 1 and Figure 2 As shown, the resistor R5 is a sampling resistor, and the voltage differential signal is taken out from both ends of the resistor R5. The sampling resistor is selected to have characteristics such as low temperature drift and high precision, so as to ensure the stable operation of the isolation amplifier and the accuracy of current sampling.

[0028] In this embodiment, the sampling resistor can be adjusted accordingly according to the actual working current, so as to achieve the maximum energy-saving effect.

[0029] Specifically, as shown in Figure 2 and Figure 3 As shown, the secondary operational amplifier module specifically includes: operational amplifier U7A, capacitor C9, resistor R6, resistor R8, resistor R10, operational amplifier U7B, resistor R9, capacitor C11, diode D3, diode D4; the negative input terminal of operational amplifier U7A is electrically connected to one end of R8, the other end of R8 is grounded, one end of R8 is electrically connected to one end of resistor R6, the other end of resistor R6 is electrically connected to the output terminal of operational amplifier U7A, the positive input terminal of operational amplifier U7A is electrically connected to one end of resistor R10, and the other end of resistor R10 is electrically connected to the output terminal of the isolation operational amplifier module; the positive power supply of operational amplifier U7A is connected to a 3V power supply, the positive power supply of operational amplifier U7A is electrically connected to one end of capacitor C9, the other end of capacitor C9 is grounded to GND2, and the negative power supply of operational amplifier U7A is grounded to GND2; the output terminal of operational amplifier U7A is electrically connected to the positive input terminal of operational amplifier U7B, the output terminal of operational amplifier U7B is electrically connected to one end of resistor R9, the other end of resistor R9 is electrically connected to one end of capacitor C11, the negative input terminal of operational amplifier U7B is electrically connected to one end of resistor R9, the other end of capacitor C11 is grounded, one end of capacitor C11 is electrically connected to the negative electrode of diode D3, the positive electrode of diode D3 is grounded to GND2, one end of capacitor C11 is electrically connected to the positive electrode of diode D4, the negative electrode of diode D4 is electrically connected to the power supply terminal, and one end of capacitor C11 is electrically connected to the control module.

[0030] In this embodiment, the current sampling is converted into a voltage differential signal, which is accurate, anti-interference, and not affected by ground isolation. As shown in Figure 3As shown in the figure, the two ends of the resistor are respectively connected to the INP terminal and INN terminal of the isolation operational amplifier chip, and its value only depends on the voltage difference across the sampling resistor. Among them, R7 and R11 are current-limiting resistors for current limiting, and C10 is used for port filtering. The values can be flexibly set according to the actual PCB layout to improve accuracy. After the isolation operational amplifier module outputs a single-ended 1:1 small signal, the reference can be adjusted. R12 is directly connected to GND, that is, the reference value is set to 0V, or the reference voltage can be raised according to the actual application. The small signal at the back end of isolation is amplified and followed by an operational amplifier, and then connected to the MCU. The logic is simple and the amplification factor can be adjusted flexibly.

[0031] Specifically, as Figure 1 shown in the figure, the control module is specifically an MCU module. The input terminal of the MCU module is electrically connected to the control terminal, and the output terminal of the secondary operational amplifier module is electrically connected to the input terminal of the MCU module. The logic strategy of the MCU module is flexible and can monitor the current in real time and upload it to the superior device.

[0032] In this embodiment, the current sampling is converted into a voltage differential signal, which is respectively connected to the INP terminal and INN terminal of the isolation operational amplifier U6 through resistors R7 and R11. Its value only depends on the voltage difference across the sampling resistor. At the same time, the voltage difference between the INP terminal and INN terminal will be converted into the voltage of the OUT pin at the output terminal, that is, a 1:1 small signal voltage. Then, through the first-stage amplification and second-stage following of the operational amplifier, the amplified voltage signal is given to the MCU to realize voltage acquisition. According to the voltage value collected by the MCU, the current value at the power supply inlet is deduced. The specific calculation process is as follows:

[0033] It is known that the voltage collected by the MCU is U0, then the current I0 at the front end of the isolation system can be calculated as follows:

[0034] U0 = U2(1 + R6 / R8). From this, the voltage U2 before the operational amplifier amplification can be calculated as U2 = (U0 * R8) / (R6 + R8), where U2 is the voltage of pin 3 of the operational amplifier U7.

[0035] Then the differential voltage between pins 2 and 3 at the front end of the isolation operational amplifier is U3 = U2 = (U0 * R8) / (R6 + R8);

[0036] Then the input current is: I0 = U3 / R5 = (U0 * R8) / [(R6 + R8) * R5].

[0037] In the specific working process of the isolation current sampling circuit of this embodiment, the isolation operational amplifier converts the current sampling signal at the front end of isolation into a single-ended small voltage signal at the back end of isolation, and then connects to the MCU through the operational amplifier for acquisition to realize the acquisition of the front-end current.

[0038] The above are only the preferred specific embodiments of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model, according to the technical solution of the present utility model and its inventive concept, makes equivalent substitutions or changes, and should be covered within the protection scope of the present utility model.

Claims

1. An isolation current sampling circuit, characterized in that, Including: An isolated front-end power module for providing voltage for a subsequent-stage load and an isolation operational amplifier module, and simultaneously collecting the input current of the load through a sampling resistor. The sampling resistor converts the collected input current into a voltage differential signal and transmits the voltage differential signal to the isolation operational amplifier module; An isolation operational amplifier module for converting the voltage differential signal into a small voltage signal with a voltage ratio of one to one corresponding to the voltage difference of the voltage differential signal, and transmitting the small voltage signal to a secondary operational amplifier module; A secondary operational amplifier module for amplifying the small voltage signal by a preset amplification factor to obtain an amplified voltage signal, and the amplified voltage signal; A control module for converting the amplified voltage signal into a corresponding current value to obtain the current value at the power supply inlet; Wherein, the isolated front-end power module is electrically connected to the input end of the isolation operational amplifier module through a sampling resistor, the output end of the isolation operational amplifier module is electrically connected to the input end of the secondary operational amplifier module, and the output end of the secondary operational amplifier module is electrically connected to the input end of the control module.

2. The isolation current sampling circuit according to claim 1, wherein The isolation operational amplifier module specifically includes an isolation operational amplifier U6, a resistor R7, a resistor R11, a resistor R12, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, and a capacitor C10; the INP end of the isolation operational amplifier U6 is electrically connected to one end of the capacitor C10, the other end of the capacitor C10 is electrically connected to the INN end of the isolation operational amplifier U6, the other end of the capacitor C10 is electrically connected to one end of the resistor R11, the other end of the resistor R11 is grounded to GND1, one end of the capacitor C10 is electrically connected to one end of the resistor R7, the other end of the resistor R7 is grounded to GND2, the GUD1 end of the isolation operational amplifier U6 is grounded to GUD1, the GUD2 end of the isolation operational amplifier U6 is grounded to GUD2, the REFIN end of the isolation operational amplifier U6 is electrically connected to one end of the resistor R12, the other end of the resistor R12 is grounded to GND2, the VDD1 end of the isolation operational amplifier U6 is electrically connected to one end of the capacitor C5, the VDD1 end of the isolation operational amplifier U6 is electrically connected to one end of the capacitor C8, the other end of the capacitor C8 and the other end of the capacitor C5 are commonly grounded to GUD1, one end of the capacitor C5 is electrically connected to a 5V power supply, the VDD2 end of the isolation operational amplifier U6 is electrically connected to one end of the capacitor C6, the VDD2 end of the isolation operational amplifier U6 is electrically connected to one end of the capacitor C6, the other end of the capacitor C6 and the other end of the capacitor C7 are commonly grounded to GUD1, one end of the capacitor C6 is electrically connected to a 5V power supply, the OUT end of the isolation operational amplifier U6 is electrically connected to the input end of the secondary operational amplifier module, and the voltage differential signal is connected to the INP end and the INN end of the isolation operational amplifier U6 through the resistors R7 and R11.

3. The isolation current sampling circuit according to claim 1, characterized in that The isolated front-end power module specifically includes: capacitor C1, capacitor C4, resistor R5, reverse protection diode D1, electrolytic capacitor C2, capacitor C3, bidirectional TVS diode D2, fuse FU1. One end of capacitor C1 is electrically connected to one end of capacitor C4. The other end of capacitor C4 is grounded to GND1. One end of capacitor C1 is grounded to EGND. The other end of capacitor C1 is electrically connected to one end of fuse FU1. One end of fuse FU1 is electrically connected to one end of bidirectional TVS diode D2. The other end of bidirectional TVS diode D2 is electrically connected to the other end of capacitor C4. The other end of fuse FU1 is electrically connected to the positive electrode of reverse protection diode D1. The negative electrode of reverse protection diode D1 is electrically connected to the positive electrode of electrolytic capacitor C1. The negative electrode of electrolytic capacitor C1 is electrically connected to one end of resistor R5. The other end of resistor R5 is grounded to GND1. The negative electrode of electrolytic capacitor C1 is electrically connected to one end of capacitor C3. The positive electrode of electrolytic capacitor C1 is electrically connected to the other end of capacitor C3. The negative electrode of electrolytic capacitor C1 is grounded to GND2. The positive electrode of electrolytic capacitor C1 is electrically connected to the load. One end of capacitor C1 is connected to the power supply V_IN+ terminal.

4. The isolation current sampling circuit according to claim 3, wherein, Resistor R5 is a sampling resistor, and the voltage differential signal is taken out from both ends of resistor R5.

5. The isolation current sampling circuit according to claim 1, wherein The secondary operational amplifier module specifically includes: operational amplifier U7A, capacitor C9, resistor R6, resistor R8, resistor R10, operational amplifier U7B, resistor R9, capacitor C11, diode D3, diode D4; the negative input terminal of operational amplifier U7A is electrically connected to one end of R8. The other end of R8 is grounded. One end of R8 is electrically connected to one end of resistor R6. The other end of resistor R6 is electrically connected to the output terminal of operational amplifier U7A. The positive input terminal of operational amplifier U7A is electrically connected to one end of resistor R10. The other end of resistor R10 is electrically connected to the output terminal of the isolation operational amplifier module; the positive power supply input of operational amplifier U7A is connected to the 3V power supply. The positive power supply input of operational amplifier U7A is electrically connected to one end of capacitor C9. The other end of capacitor C9 is grounded to GND2. The negative power supply of operational amplifier U7A is grounded to GND2; the output terminal of operational amplifier U7A is electrically connected to the positive input terminal of operational amplifier U7B. The output terminal of operational amplifier U7B is electrically connected to one end of resistor R9. The other end of resistor R9 is electrically connected to one end of capacitor C11. The negative input terminal of operational amplifier U7B is electrically connected to one end of resistor R9. The other end of capacitor C11 is grounded. One end of capacitor C11 is electrically connected to the negative electrode of diode D3. The positive electrode of diode D3 is grounded to GND2. One end of capacitor C11 is electrically connected to the positive electrode of diode D4. The negative electrode of diode D4 is connected to the power supply terminal. One end of capacitor C11 is electrically connected to the control module.

6. The isolated current sampling circuit according to claim 1, wherein The control module is specifically an MCU module. The input terminal of the MCU module is electrically connected to the control terminal. The output terminal of the secondary operational amplifier module is electrically connected to the input terminal of the MCU module.

Images