63 results about "Diode voltage" patented technology

The invention relates to an ultra-low power consumption control method and system for a coal mine vibration sensor, and belongs to the technical field of dust treatment. The problems that a detection circuit cannot sleep and standby power consumption is too large due to continuous vibration signals are solved. According to the technical scheme, a vibration signal direct-current component is removed through an alternating-current coupling module, an alternating-current signal is converted into a one-way pulse signal through a rectification amplification module, and a stable direct-current voltage Vk is generated through a low-pass filtering module. The threshold value comparison module compares the Vk with a preset threshold value Vref in real time, and when the output level of the comparator jumps, the MCU is awakened to process the vibration state and sleep again. The system adopts a dual-mode switching mechanism: switching to a low-level wake-up mode after a high-level trigger processing vibration existence event, and switching to a high-level wake-up mode after a low-level trigger processing vibration disappearing event. According to the method, deep dormancy in a continuous vibration environment is realized, invalid wake-up times are reduced, the influence of diode voltage drop is eliminated, and the target of ultra-low standby power consumption is achieved.

The invention discloses a zero-input current ripple wide-gain DC-DC converter and a control method, the zero-input current ripple wide-gain DC-DC converter comprises a zero-ripple boost unit and a voltage multiplication unit which are connected in sequence, and the zero-ripple boost unit comprises a first inductor, a second inductor, a third capacitor, a fourth capacitor, a first power switch and a third diode; the voltage multiplication unit comprises a first capacitor, a second capacitor, a first diode, a second diode, a third diode, a third inductor and a second power switch. By introducing the zero-ripple boost unit, the zero-input ripple characteristic is realized while the voltage gain is improved, and meanwhile, the voltage multiplication unit is introduced, so that the structure has a function similar to that of a switched capacitor and optimizes the energy circulation of the switched capacitor; therefore, the voltage gain of the converter is further improved, and the voltage and current stress of the semiconductor device is reduced.

The invention provides a body diode voltage drop on-line measurement circuit and a design method thereof. The design method comprises the following steps: determining an expression of body diode voltage drop in a body diode conduction state in a measured power device based on a power device structure model; the method comprises the following steps: determining a measurable time period and a measurement strategy for online measurement of the body diode voltage drop of a measured power device based on a current flowing state and gate-source voltage characteristics of an inverter in a complete period; and designing the body diode voltage drop on-line measurement circuit based on the measurable time period and the measurement strategy. According to the technical scheme of the invention, the characteristics of the voltage drop of the diode of the power device in the working process of the inverter are deeply analyzed, and the circuit capable of carrying out simple, accurate and low-cost online measurement on the inverter is reasonably designed.

The DRAM temperature monitoring self-refresh circuit and the DRAM provided by the embodiments of the present disclosure comprise: a self-refresh enabling module, which outputs a clock signal to a reference voltage generating module and a logic module upon receiving a self-refresh enabling signal; the reference voltage generating module determines a first clock sampling signal according to the received clock signal, and generates a reference voltage to a comparison module according to the first clock sampling signal; the comparison module outputs a comparison signal to the logic module according to the reference voltage and a diode voltage; the logic module generates a sampling signal to collect the first clock sampling signal of the reference voltage generating module at a first time according to the clock signal and the comparison signal when the comparison signal is at a high level, so as to generate a temperature identification signal according to the first clock sampling signal, and determine a chip refresh clock according to the temperature identification signal and the clock signal, and generates a reset signal to the reference voltage generating module at a second time, so as to reset the first clock sampling signal of the reference voltage generating module.

The invention provides a SiC MOSFET DC power cycle accelerated life test system and method. The system comprises a DC power supply, a main power circuit, a conduction voltage drop measurement circuit and a controller. The main power circuit comprises N device sub-circuits which are connected in parallel, and each device sub-circuit is provided with a SiC MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor); the conduction voltage drop measuring circuit comprises N measuring sub-circuits which are respectively connected with the SiCMOSFETs of the N device sub-circuits; the measurement sub-circuit is used for measuring the conduction voltage drop of the SiC MOSFET when the connected device sub-circuit is switched on and the body diode voltage drop of the SiC MOSFET when the connected device sub-circuit is switched off in a preset cycle period; the controller is used for controlling the N device sub-circuits to be sequentially switched on within the power-on time, and only one device sub-circuit is switched on; and obtaining the body diode voltage drop sequence of the SiC MOSFET in the preset cycle period collected by each measurement sub-circuit, thereby determining the junction temperature sequence of the SiC MOSFET of each device sub-circuit. According to the invention, accelerated life tests of SiC MOSFETs under a plurality of different working conditions can be realized at the same time, and the test efficiency is improved.

A junction temperature calibration method, junction temperature detection method and device for an IGBT device belong to the technical field of junction temperature calibration, and the method comprises the following steps: obtaining IGBT junction temperature calibration data; wherein the IGBT junction temperature calibration data comprises conduction voltage drop, junction temperature and conduction current; fitting a junction temperature calibration fitting function according to the IGBT junction temperature calibration data, and determining the relationship among the conduction voltage drop, the junction temperature and the conduction current to obtain a junction temperature calibration relational expression; wherein the junction temperature calibration fitting function is constructed through a diode voltage drop calculation formula and an MOSFET voltage drop calculation formula. The junction temperature calibration fitting function is established based on the physical principle in the IGBT, and the problems that an existing junction temperature calibration function is poor in precision and the calibration process is complex are solved.

A method (100) for determining a capacitively smoothed rotor current of an inductive transformer (1) of a separately excited electrical machine is disclosed, preferably for controlling the capacitively smoothed rotor current for driving a rotor (40) of the separately excited electrical machine. The method comprises: determining a capacitor voltage (110) of a secondary intermediate circuit capacitor (22) of the inductive transformer (1) using a primary current of the inductive transformer (1), an equivalent circuit of a transformer (30) of the inductive transformer (1), and a diode voltage of a first diode (21).1) of a rectifier circuit (21) of the inductive transformer (1); Determining a transmission power (120) of the inductive transformer (1) using the primary current and a primary voltage of the inductive transformer (1); Determining a rotor resistance (130) using the capacitor voltage, the transmission power and detected disturbance signals of the rotor (40); and Determining the rotor current (140) using the capacitor voltage, the rotor resistance and the disturbance signals.

A method for controlling the rotational speed or the torque of a motor to protect a suppressor diode in a control device of a vehicle, wherein the suppressor diode converts recuperation energy of the motor into thermal energy comprises determining the current junction temperature and / or diode voltage of the suppressor diode; and controlling the rotational speed or the torque of the motor by means of the current junction temperature and / or diode voltage in such a way that the junction temperature of the suppressor diode does not exceed a predetermined junction temperature limit value.

According to the DRAM temperature monitoring self-refresh circuit and the DRAM provided by the embodiment of the invention, a self-refresh enable module outputs a clock signal to a reference voltage generation module and a logic module when receiving a self-refresh enable signal; the reference voltage generation module determines a first clock sampling signal according to a received clock signal, generates a reference voltage according to the first clock sampling signal and sends the reference voltage to the comparison module; the comparison module outputs a comparison signal to the logic module according to the reference voltage and the diode voltage; when the comparison signal is at a high level, the logic module generates a sampling signal at a first moment according to the clock signal and the comparison signal, collects a first clock sampling signal of the reference voltage generation module, generates a temperature identification signal according to the first clock sampling signal, and determines a chip refresh clock according to the temperature identification signal and the clock signal; and generating a reset signal to the reference voltage generation module at a second moment so as to reset the first clock sampling signal of the reference voltage generation module.

This invention discloses an LLC resonant converter with a wide output voltage range based on a voltage doubler rectifier, applicable to DC fast charging of new energy vehicles. The converter achieves primary-side inversion and secondary-side rectification topology reconfiguration through switch drive signals, enabling wide-range voltage output in four operating modes. The primary side can switch between half-bridge and full-bridge inversion modes, while the secondary side can switch between full-bridge, voltage doubler, and voltage quadruple rectifier modes. This invention reduces diode voltage stress, possesses self-balancing capability of the voltage doubler capacitor, and achieves soft switching across the entire voltage range. Ultra-wide voltage gain is achieved within a narrow frequency adjustment range across the entire voltage range through simple pulse frequency modulation (PFM), allowing the converter to adapt to the charging needs of new energy vehicles with different voltage platforms.

The invention discloses an on-resistance detection circuit and system of a gallium nitride power switch tube. The circuit comprises a voltage output circuit, a capacitor, a first voltage clamping circuit, a charging diode, a discharging diode, a voltage detector and a control unit. When the gallium nitride power switch tube is disconnected, the capacitor is charged, the capacitor is connected with the source electrode and the drain electrode of the gallium nitride power switch tube in parallel, and the first voltage clamping circuit limits the voltage between the source electrode and the drain electrode of the gallium nitride power switch tube by limiting the voltage at the two ends of the capacitor. Therefore, the voltage between the source electrode and the drain electrode is limited when the gallium nitride power switch tube is switched off. When the gallium nitride power switch tube is switched on, the anode end voltage of the discharge diode can be detected based on the voltage detector, the tube voltage drop of the discharge diode is subtracted to obtain the switch-on voltage of the gallium nitride power switch tube, and the switch-on resistance of the gallium nitride power switch tube is calculated based on the output current of the gallium nitride power switch tube. According to the scheme, the on-resistance detection precision of the gallium nitride power switch tube can be improved.

The invention discloses a micropower-oriented high-efficiency dual-frequency omnidirectional circularly polarized radio frequency rectification antenna. The antenna comprises a receiving antenna unit and a dual-frequency rectification circuit unit which are connected with each other. The receiving antenna adopts a dual-frequency omnidirectional circular polarization design; the double-frequency rectification circuit comprises a diode branch and a load branch which are connected in parallel. The diode branch comprises a coupling microstrip line, a pilot frequency impedance conversion network and a dual-frequency harmonic suppression structure which are connected in sequence; the load branch is formed by connecting a straight-through filter with a load in series. The double-frequency harmonic suppression structure forms a band-stop characteristic at the secondary harmonic of the double working frequency points; the pilot frequency impedance conversion network realizes a double-frequency-point same-input impedance characteristic; the coupling microstrip line enhances the voltage amplitude of the diode so as to improve the rectification efficiency of the circuit under the condition of micro input power. The antenna has good omnidirectivity and circular polarization performance, and can collect dual-frequency, multi-direction and multi-polarization electromagnetic waves; and meanwhile, the rectifier has the advantages of high rectification efficiency, small size and compact structure under a micro-input power condition, and better meets the requirement of collecting weak radio frequency energy in an actual scene.

The invention belongs to the technical field of DC-DC boost, and relates to a high-efficiency boost converter, a control method thereof and application of the high-efficiency boost converter in a photovoltaic or fuel cell power generation system. The converter is composed of two inductors, three switching tubes, six capacitors, six diodes and a current-limiting resistor, automatic current sharing of the input inductors can be achieved, input current ripples are small, the voltage gain reaches 6 / (1-D), the voltage stress of the switching tubes is Uo / 6, the voltage stress of the diodes is Uo / 3, current spikes and voltage spikes do not exist, and therefore the converter can be applied to large-scale production. And soft start and switch tube common-ground driving can be realized.

An integrated circuit includes a current source, a diode device, a switching circuit, an analog-to-digital converter, and a processing circuit. The current source provides a reference current. The switching circuit causes the diode device to provide a first diode having a first size to receive the reference current during a first period of time, and additionally causes the diode device to provide a second diode having a second size to receive the reference current during a second period of time. The analog-to-digital converter converts a first voltage across the first diode to a first diode voltage value, and converts a second voltage across the second diode to a second diode voltage value. The processing circuit performs an arithmetic operation on the first and second diode voltage values to generate a digital bandgap value.

The utility model provides a silicon carbide MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) capable of reducing the voltage drop of a body diode. The lower side surface of an epitaxial layer is connected to the upper side surface of a silicon carbide substrate; a first groove is formed in the epitaxial layer; the P-type base region is arranged in the first groove, and a second groove is formed in the P-type base region; the N + source region is arranged in the second groove; the P + source region is arranged in the second groove, and the outer side surface of the P + source region is connected to the inner side surface of the N + source region; the lower side surface of the gate oxide layer is connected to the N + source region, the P-type base region and the epitaxial layer; the lower side surface of the polycrystalline silicon electrode layer is connected to the upper side surface of the gate oxide layer; the lower side surface of the first contact metal layer is connected to the N + source region; the lower side surface of the second contact metal layer is connected to the P + source region, and the second contact metal layer is connected to the first contact metal layer; the metal work function of the first contact metal layer is smaller than that of the second contact metal layer; and on the basis of reducing the on resistance, the forward voltage drop of the body diode is reduced, and the loss of the MOSFET when being applied in a circuit is also reduced.

The invention relates to a test method for simulating a motor load by a refrigerator controller, which comprises an integral closed-loop test system consisting of a computer, a direct-current stabilized power supply, the refrigerator controller and a simulation load device, a singlechip outputs three paths of Hall signals to the refrigerator controller, and the controller generates a PWM (Pulse-Width Modulation) signal after receiving the Hall signals; a three-phase motor driving signal is output to a simulation load, an ADC input signal capturing device of the simulation load collects three paths of AD signals, PWM duty ratio and frequency, required parameters are used for simulating temperature measuring diode voltage in real time through a DAC output algorithm and a simulation temperature measuring diode DAC, the temperature measuring diode voltage is fed back to a controller, and closed-loop control is formed. According to the invention, the simulated load is used for simulating the motor performance of the refrigerating machine and replacing the refrigerating machine motor to carry out the closed-loop control test of the temperature control function of the controller, and the simulated load is used for replacing the refrigerating machine with relatively high price, so that the price is low, the test cost is greatly reduced, and the test efficiency is also greatly improved.

An electrostatic discharge protection device includes a diode, a voltage clamping component, an electronic component, a first pin, and a second pin. The diode includes a first doped area of a first conductivity type and a second doped area of a second conductivity type opposite to the first conductivity type. The voltage clamping component is electrically connected to the first doped area. The electronic component includes a first region of the first conductivity type, a second region of the second conductivity type, a third region of the first conductivity type, and a fourth region of the second conductivity type. The first region is electrically connected to the second doped area. The second region is electrically connected to the first doped area and the voltage clamping component. The fourth region is electrically connected to the voltage clamping component.

An integrated circuit includes a current source, a diode device, a switch circuit, an analog-to-digital converter (ADC), and a processing circuit. The current source provides a reference current. The switch circuit enables the diode device to provide a first diode with a first size for receiving the reference current during a first interval, and enables the diode device to provide a second diode with a second size for receiving the reference current during a second interval. The ADC converts a first voltage across the first diode into a first diode voltage value, and converts a second voltage across the second diode into a second diode voltage value. The processing circuit performs an arithmetic operation upon the first diode voltage value and the second diode voltage value to generate a digital bandgap value.

The invention discloses a composite aging characteristic characterization method and device of a silicon carbide MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), gate-oxide aging evaluation is carried out through static and dynamic characteristic fusion of threshold voltage drift and current rise time, and body diode bipolar degradation evaluation is carried out based on the change percentage of the on resistance of the silicon carbide MOSFET. And whether packaging aging occurs or not is judged through comparison between the change percentage of the on-resistance under the body diode voltage drop or different gate voltages and the offset of the on-resistance curve, so that precise decoupling of bipolar degradation and packaging aging of the body diode is realized, precise separation of gate-oxide aging, bipolar degradation and packaging aging of the body diode is realized, and the reliability of the device is improved. The technical problem that the existing aging characteristic decoupling characterization does not consider the influence of the bipolar degradation of the body diode, when the bipolar degradation of the body diode occurs in the device, whether the packaging degradation occurs at the same time is difficult to judge, and the accuracy of the aging characteristic characterization of the silicon carbide MOSFET is influenced is solved.

A method (100) for determining a channel resistance value of an electronic semiconductor switching element (M1) is disclosed, comprising: determining a diagnostic voltage value (U) DESAT ) (110) based on a provided diode voltage value (U) D,DESAT ) of a diode (D DESAT ) a diagnostic circuit (20); and a determination of the channel resistance value (R) DS ) (120) based on a calculation of the diagnostic voltage value (U DESAT ), a provided evaluation voltage value (V DESAT ) the diagnostic circuit (20) and a provided load current value (I LOAD ) of the electronic semiconductor switching element (M1). Also disclosed is a computing unit (30) configured to execute the method and an electronic circuit device (10) with the computing unit (30).

The present invention discloses a watt-level microwave rectifier circuit, which belongs to the technical field of basic electrical components. The rectifier circuit includes: a microwave input part, a microwave rectifier part, and a DC output part. The microwave rectifier part adopts a symmetrical rectifier branch parallel structure, which improves the rectifier power capacity. Through the microstrip line design in the microwave rectifier part and the DC output part, a harmonic recovery control network is constructed to shape the diode voltage and current waveforms, realize the recovery of the third harmonic energy and improve the rectification efficiency, and realize high-efficiency watt-level rectification; through the impedance smoothing network, the impedance fluctuation of the diode under different input powers is effectively suppressed, and combined with the design of the second harmonic control network, wide input watt-level microwave rectification is realized. The rectifier circuit design method provided by the present invention realizes high-performance watt-level microwave rectification, with a simple and compact design and reduced cost.

The invention discloses a SiC MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) driving circuit, which belongs to the field of power electronics and comprises an input side preprocessing and fault detection unit, an input side logic time sequence unit, a signal isolation unit, an output side logic unit, an output side power amplification and fault detection unit, an upper tube power supply management unit and a lower tube power supply management unit, the input side preprocessing and fault detection unit is electrically connected with the input side logic time sequence unit, the input side logic time sequence unit is electrically connected with the signal isolation unit, the signal isolation unit is electrically connected with the output side logic unit, and the output side logic unit is electrically connected with the output side power amplification and fault detection unit. The input side preprocessing and fault detection unit is electrically connected with the upper tube power supply management unit and the lower tube power supply management unit at the same time. According to the invention, different negative voltage values are used for suppressing crosstalk voltage; the crosstalk voltage is prevented from exceeding the threshold voltage to cause misconduction; the negative voltage is prevented from being too low, and the diode voltage drop is improved.

The application discloses a kind of permanent magnet synchronous motor position sensorless inverter nonlinear compensation control system and method, the method first establishes the accurate voltage source type inverter nonlinear model including dead zone, switching device on-off delay and switch tube and diode voltage drop;Second, for the mapping relationship of D( i x ) and D( i x / 2), a kind of based on q Shaft current injection method is proposed, the nonlinear compensation of voltage source type inverter is realized;Finally, with rotor position estimation accuracy as the basis for judging the nonlinear compensation effect of inverter, complete low-speed working condition position sensorless control inverter nonlinear compensation.Compared with the conventional method, the inverter nonlinear compensation method provided by the application can significantly improve the running performance of permanent magnet synchronous motor position sensorless control in extremely low speed interval, effectively reduce rotor position estimation error.

The utility model discloses a current-limiting retraction protection circuit, which relates to the field of switching power supply current-limiting protection and comprises a current detection circuit, a current reference setting circuit and an error amplification circuit, the current reference setting circuit comprises a first operational amplifier, a first diode, a voltage detection circuit and a maximum output current setting circuit; the input end of the error amplification circuit, the output end of the voltage detection circuit and the anode of the first diode are connected with the inverted input end of the first operational amplifier, and the cathode of the first diode is connected with the output end of the first operational amplifier; the in-phase input end of the first operational amplifier is connected with the output end of the maximum output current setting circuit; the error amplification circuit is used for comparing the output end voltage of the current detection circuit with the output end voltage of the current reference setting circuit. A high-precision resistor and a low-offset-voltage operational amplifier are used, so that an output current retraction point and a maximum current limiting point can be accurately set.

The invention relates to a CIGS (Copper Indium Gallium Selenide) battery photovoltaic module adopting a bypass diode structure and a preparation method of the CIGS battery photovoltaic module, and solves the problems that a diode needs to be welded between every two battery pieces to inhibit a hot spot effect, the CIGS module is easy to damage and difficult to maintain, and the output power is influenced in the conventional CIGS module. The device comprises a plurality of CIGS battery photovoltaic modules which are connected in series or in parallel, each CIGS battery photovoltaic module comprises a front film, a conductive grid is arranged on each front film, a plurality of CIGS battery pieces which are connected in series through the conductive grids are attached to each front film, and a positive bus bar and a negative bus bar are arranged at the two ends of the conductive grid on the front film of each CIGS battery photovoltaic module respectively. The end parts of the same sides of the positive bus bar and the negative bus bar respectively extend outwards and are provided with diode extension circuits; and bypass diodes are connected in series in the diode extension circuits in a welding manner. According to the invention, the connection and configuration of the battery pieces are simplified, and the requirement for complex electrical connection is also reduced; moreover, the use of diodes is effectively reduced, and the power loss of the module caused by the voltage drop of the diodes is reduced.

The application discloses an integrated amplifier circuit, which comprises an input signal conditioning module, a front-stage signal amplification module, an intermediate signal amplification module and a power output module connected in sequence. The input conditioning module is isolated from direct current through double-coupling capacitors, and impedance matching and current-voltage conversion are completed through resistors, so that direct current interference and input waveform distortion are eliminated. The front stage adopts a double-NPN triode amplification structure matched with a diode voltage-stabilized bias to realize primary amplification of weak pulse signals. The intermediate stage completes secondary signal amplification through combined triodes and relies on a compensation capacitor to suppress self-oscillation. The power output module adopts a double-NPN triode push-pull structure to improve signal driving capacity and simultaneously has overload protection and direct current isolation output functions. The circuit has the advantages of simple structure, strong anti-interference performance, excellent amplification precision and driving performance, and can effectively improve the problems of distortion and easy self-excitation of traditional circuits, and is suitable for weak pulse signal amplification scenes.

This invention discloses an apparatus for measuring oxygen saturation. The apparatus includes a circuit system configured to: measure a first diode voltage at a light-emitting diode (LED) when a first current is applied through the LED; measure a second diode voltage at the LED when a second current is applied through the LED; and measure a third diode voltage at the LED when a third current is applied through the LED. The circuit system is further configured to: determine a series resistance based on the first, second, and third diode voltages; and determine the intensity of a received photon signal corresponding to an output photon signal generated using the LED. The circuit system is further configured to determine the oxygen saturation level based on the intensity of the received photon signal and the series resistance.

The application discloses a variable threshold temperature switch circuit, and belongs to the field of integrated circuits, comprising a bandgap reference bias module, a PTAT voltage generation module, a CTAT voltage generation module and a comparator; the bandgap reference bias module is designed based on a bandgap reference source model, combines a common source and common gate structure, realizes a PTAT bias current with a positive temperature change of a high power supply rejection ratio, and provides bias for other modules; the PTAT voltage generation module is provided with a PTAT bias current by the bandgap reference bias module, generates a PTAT voltage with a positive temperature change; the CTAT voltage generation module generates a CTAT voltage with a negative temperature change due to the negative temperature characteristic of a diode voltage V BE ; and the comparator is provided with bias by the bandgap reference bias module, adopts a two-stage structure, and outputs a result after shaping.

This application relates to improved bit-line stabilization and power supply rejection ratio in a nine-cell pixel image sensor with phase detection autofocus. An imaging device includes a pixel array of pixel circuits arranged in rows and columns. Bit-lines are coupled to the pixel circuits. Clamping circuits are coupled to the bit-lines. Each of the clamping circuits includes a clamping short transistor to a power supply line and a corresponding one of the bit-lines. The clamping short transistor is configured to be switched in response to a clamping short enable signal. A first diode voltage drop device is coupled to the power supply line. A clamping idle transistor is coupled to the first diode voltage drop device such that the first diode voltage drop device and the clamping idle transistor are coupled between the power supply line and the corresponding one of the bit-lines. The clamping idle transistor is configured to be switched in response to a clamping idle enable signal.

The utility model provides an integrated sampling circuit of a capacity checking device, which meets the requirement of collecting each electric parameter in the capacity checking process of a storage battery pack, comprises a main control chip for calculating the electric parameters, and is characterized in that the main control chip is connected with a current sampling module and a voltage sampling module; the current sampling module comprises a first electrostatic protection circuit and a first operational amplifier circuit, the input end of the first electrostatic protection circuit is connected with a current sampling terminal, the output end of the first electrostatic protection circuit is connected with the input end of the first operational amplifier circuit, and the current sampling terminal is used for being externally connected with a Hall current sensor; the voltage sampling module comprises a diode voltage drop sampling module and a battery pack voltage sampling module; the diode voltage drop sampling module comprises a second electrostatic protection circuit and a second operational amplifier circuit, the input end of the second electrostatic protection circuit is connected with the first voltage sampling terminal, and the output end of the second electrostatic protection circuit is connected with the input end of the second operational amplifier circuit.