692 results about "Dropout voltage" patented technology

The invention relates to the technical field of electronic circuit detection, in particular to a detection method for checking abnormal work of a lamp, which comprises the following steps: acquiring the consistency of a lighting state and voltage, extracting abnormal response, checking power supply connection and checking non-response, monitoring and controlling the relationship between output and current action starting, and analyzing response continuity. And detecting branch voltage difference change and direction, monitoring voltage jump and current response starting point performance, extracting response data, and obtaining a classification result. According to the invention, through cooperative detection of voltage and current response behaviors, in combination with path voltage difference direction change and time sequence characteristics, a load abnormal response section is identified step by step, the abnormal state identification capability is enhanced, an action time sequence cross validation mode is adopted to replace a traditional static judgment process, misjudgment interference is reduced, and manual intervention requirements are reduced; therefore, the detection process is more continuous, the related operation is universal, the method can be suitable for various lamp structures, the troubleshooting precision is improved, and the execution cost is controlled at the same time.

The invention, which relates to the technical field of energy storage and discharge, provides an energy storage and discharge system comprising a power supply input interface, a slow power-on unit, a slow power-on control unit, an energy storage unit, a start-stop control unit, a sampling unit, a detection unit, a main loop switch unit and an output interface. The power supply input interface is connected with the input end of the main loop switch unit and the input end of the slow power-on unit, the output end of the slow power-on unit is connected with the first port of the slow power-on control unit, and the output end of the main loop switch unit and the second port of the slow power-on control unit are connected with the port of the energy storage unit. The sampling unit is connected with the input end of the detection unit, and the output end of the detection unit is connected with the control end of the main loop switch unit. According to the invention, the problem of'maloperation 'protection of the power supply due to increase of the switching voltage difference in the process of switching the main loop can be avoided, and the reliability of the energy storage discharge system is improved.

The invention discloses a fault detection method, device and system and a storage medium. The fault detection method comprises the steps of obtaining at least two voltage sampling values; wherein the at least two voltage sampling values are obtained by at least two analog front-end modules in the battery monitoring unit through respective target sampling channels to perform voltage acquisition on the same analog battery cell; determining a voltage difference absolute value between every two voltage sampling values in the at least two voltage sampling values; and when the partial pressure difference absolute value in the at least two obtained pressure difference absolute values is greater than a preset threshold value, determining an abnormal target voltage sampling value according to the partial pressure difference absolute value, and determining that the target sampling channel of the corresponding target analog front-end module has an equalization fault according to the target voltage sampling value. Therefore, the accuracy of equalization fault identification can be improved, and the safety of the battery is further improved.

The invention discloses an optimization control method and system for an ultra-large fan intelligent speed regulator, and relates to the technical field of fan intelligent control, and the method comprises the steps: obtaining the current operation environment parameters of a fan, including but not limited to a wind speed signal, a motor input current, a voltage, a power factor, a rotating speed, an environment temperature and atmospheric pressure; monitoring whether the wind speed fluctuation amplitude exceeds a set threshold or not in a continuous sampling period; judging whether the current system enters a critical hysteresis zone state or not, wherein the critical hysteresis zone state is a working condition when the wind speed data of the sensor does not have stability and fan output has current fluctuation abnormity and a differential pressure rapid change trend; when the system enters a critical hysteresis zone state, the collected wind speed signal is paused as a speed regulation basis, an air volume estimation model based on current, voltage, rotating speed, temperature, humidity and air pressure is constructed, and equivalent air volume is output as a pseudo feedback signal; the problem that the fan speed regulation accuracy and the system stability are reduced in the plateau low-pressure environment is solved.

The utility model provides a device for stably recycling pressure energy and cold energy of natural gas. An inlet of the device is connected with upstream pipeline conveying natural gas, the device comprises a differential pressure generator set, a heat exchange unit and an expansion machine bypass pressure stabilizing unit, the differential pressure generator set and the heat exchange unit are connected in series and then connected with the expansion machine bypass pressure stabilizing unit in parallel, and the differential pressure generator set and the expansion machine bypass pressure stabilizing unit are connected into downstream natural gas using equipment after being gathered. The expansion machine bypass voltage stabilization unit comprises a first voltage stabilization and regulation unit, a second voltage stabilization and regulation unit and a third voltage stabilization and regulation unit, and the first voltage stabilization and regulation unit, the second voltage stabilization and regulation unit and the third voltage stabilization and regulation unit are connected in parallel. On the premise of ensuring normal and stable gas utilization of downstream gas utilization equipment, the device is comprehensively applied by combining an ingenious combination mode with an advanced control method, and abundant energy of natural gas can be fully recycled. And the working requirements of upstream incoming gas under the harsh working conditions of large flow and large pressure difference fluctuation change can be met.

The present invention provides a channel current calibration circuit for an LED driver chip and an LED driver chip, comprising: a calibration voltage generation module and multiple channel calibration selection modules. The calibration voltage generation module is configured to receive a first reference voltage generated by a reference voltage generation module and adjust the first reference voltage according to a preset voltage difference to obtain multiple calibration voltages, wherein the voltage difference between adjacent calibration voltages is the preset voltage difference. The channel calibration selection module is configured to receive the multiple calibration voltages and select a target calibration voltage from the multiple calibration voltages according to a first control signal from a digital controller, thereby calibrating the output current of the channel current generation module to a desired current value using the target calibration voltage. After the calibration voltage generation module adjusts the reference voltage to multiple calibration voltages, each channel calibration selection module selects the corresponding target calibration voltage to adjust the output current of the corresponding channel current generation module to the desired value.

Provided are a detection method, a control device, a power distribution box, and a storage medium. The detection method applied in a power distribution box includes: obtaining a real-time input alternating-current voltage and a zero-point alternating-current phase of the power distribution box within a utility power cycle; obtaining a simulated input alternating-current voltage of the power distribution box within the utility power cycle based on the zero-point alternating-current phase; determining that the real-time input alternating-current voltage is normal in response to an alternating-current voltage difference between the simulated input alternating-current voltage and the real-time input alternating-current voltage being smaller than or equal to a predetermined threshold, or determining that the real-time input alternating-current voltage is abnormal in response to the alternating-current voltage difference between the simulated input alternating-current voltage and the real-time input alternating-current voltage being greater than the predetermined threshold.

The invention discloses a three-level flexible excitation dynamic regulation and control method and system for a large-scale hydroelectric generating set, and relates to the technical field of flexible excitation control of the large-scale hydroelectric generating set, and the method comprises the steps: setting a DC bus voltage, and initializing a mapping relation between a capacitor voltage and an excitation output level; collecting operation parameters of a machine end, constructing a disturbance identification model and outputting a disturbance level; the excitation voltage output gear is set according to the disturbance level, the capacitor voltage difference is controlled, and dynamic voltage sharing is achieved by modulating the midpoint duty ratio. According to the method, through setting a bus target voltage and constructing excitation voltage output mapping, in combination with a disturbance level identification mechanism and a dynamic voltage-sharing strategy, closed-loop linkage of disturbance perception-voltage regulation-voltage difference control is realized. According to the method, the identification precision of the system on light disturbance and strong disturbance is effectively improved, the voltage stability and capacitance symmetry of the excitation system are enhanced, the overshoot risk is reduced, and the control robustness and safety of the system under extreme working conditions are improved.

The invention relates to the technical field of power electronic control, and provides a soft start control method for a three-phase PFC (Power Factor Correction), a PFC controller and a power supply system.The soft start control method comprises the steps that when a PFC start instruction is received, an initial target voltage value is set as an actual value of current bus voltage; maintaining the initial target voltage value for a first preset duration; after the initial stable state, sampling in real time to obtain the actual value of the current bus voltage, and calculating the absolute value of the voltage difference between the actual value of the current bus voltage and the current target voltage value; judging whether the absolute value of the voltage difference is smaller than or equal to a preset trigger threshold value; if yes, adding a preset voltage step value to the current target voltage value; if not, keeping the current target voltage value unchanged; and recursive control of the current bus voltage is executed circularly until the updated current target voltage value reaches the final target voltage value. According to the mode, the starting rapidity and the stability of the boosting process are balanced.

The invention discloses a low dropout linear regulator with a wide dropout range, which is characterized in that an error amplifier is supplied with power by output voltage of the low dropout linear regulator, and a common-gate buffer is supplied with power by input voltage of the low dropout linear regulator, so that a direct interference path of the input voltage to the output only exists in a common-gate buffer stage and an output stage; and the power supply rejection ratio is improved. The common-gate buffer solves the problem of margin loss caused by a traditional source follower circuit, a positive feedback loop arranged in the common-gate buffer is used for improving the slew rate of a driving signal VPGATE and providing a certain gain, and therefore the problem of margin under low dropout is solved, and the reliability of the driving circuit is improved. And the compensation circuit can adjust the compensation amount of the low-dropout linear regulator when the input voltage is higher than a preset threshold value, so that the stability of the low-dropout linear regulator under different working conditions is improved.

The invention belongs to the field of power electronic converter control and design, and discloses a carrier modulation method and system for achieving accurate control over the neutral-point potential of a three-level inverter. The neutral-point voltage is kept in a relatively balanced state by detecting and correcting the voltage difference of an upper capacitor and a lower capacitor on the direct current side in time; and the distortion of the output voltage at the alternating current side caused by large fluctuation of the neutral-point potential is reduced or avoided. A midpoint potential correction link is introduced while the advantages of a conventional SVM or carrier modulation are not damaged; and when the neutral-point potential deviates, the zero-sequence voltage is automatically injected or a proper switching vector sequence is selected to compensate, suppress harmonic waves and reduce the distortion degree, so that the waveform quality of the output voltage is improved.

The invention provides a comprehensive evaluation method for the operation effect of a power grid side energy storage power station, and relates to the technical field of energy storage power station evaluation.The comprehensive evaluation method comprises the steps that a historical evaluation data set is obtained, discrete processing is conducted on the evaluation data set, then the time length t is selected as the evaluation time length, and the normal distribution of voltage in the power grid side evaluation time length is calculated; obtaining an adjusted voltage difference curve according to the voltage of the power grid side and the point voltage of the user side, calculating the adjustment coefficient of the energy storage power station, calculating the daily average loss and the economic coefficient by calculating the theoretical electricity price and the actual electricity price of the energy storage power station according to the historical maintenance cost, carrying out regional division on each energy storage power station, and clustering the regions through a clustering method. And calculating a coordination coefficient of the energy storage power station according to a clustering result, dynamically adjusting the weights of the adjustment coefficient and the coordination coefficient through a weighted adaptive algorithm, and calculating a comprehensive evaluation index according to the adjusted weights.

The invention discloses a detection control method for a brush motor, a controller, a system and electrical equipment, relates to the technical field of motors, and can improve the detection accuracy of the working state of the motor under the condition of not influencing the cost. The detection control method for the brush motor comprises the steps that sampling current is obtained, the sampling current is obtained according to the voltage difference between the two ends of a sampling resistor, and the sampling resistor is arranged in a drive circuit of the brush motor; performing ripple algorithm processing on the sampling current to obtain the ripple amplitude of the working current corresponding to the brush motor; and detecting the working state of the brush motor according to the ripple amplitude of the working current and the numerical value of the working current.

The invention provides an output negative voltage protection circuit applied to an N-type power device linear voltage regulator. The output negative voltage protection circuit comprises a voltage comparator, a current comparator, an error amplifier, a buffer driver, a power device MP, a resistor R1, a resistor R2, a resistor Rload and a capacitor Cout. The method comprises the following steps: acquiring a voltage difference between an S-pole output voltage Vout of a power device MP and a reference voltage Vos through a voltage comparator, converting the voltage difference into a current signal Ieg, and comparing the current signal Ieg with a reference current Ios through a current comparator to generate a current signal Ilim; adjusting the output of an error amplifier according to the current signal Ilim, and dynamically adjusting the G pole voltage Vgate of the power device MP; when the output voltage Vout is lower than the reference voltage Vos, the G pole voltage Vgate is pulled down to turn off the power device MP through the current signal Ilim, and protection of the power device MP is achieved.

The utility model discloses a shock absorption type micro differential pressure switch, which comprises a signal end protection installation plastic shell and a pressure cavity low-pressure end shell, the pressure cavity low-pressure end shell is fixed at the lower end of the signal end protection installation plastic shell through a bolt, and a sheath lead cable is fixedly arranged on one side of the signal end protection installation plastic shell. A wiring terminal is fixedly arranged on one side of the sheath wire cable, and a shock absorption mechanism is arranged between the signal end protection installation plastic shell and the pressure cavity low-pressure end shell. In the process of the utility model, the ball head thread transmission idle rod does not directly push the spherical button, the shock absorption pressure spring needs to overcome the pre-tightening force of the shock absorption pressure spring to deform, and a period of time is needed in the process of pushing the spherical button to overcome the pre-tightening force of the shock absorption pressure spring, so that the effect of eliminating differential pressure fluctuation in the time process is achieved; and the spherical button pushes the microswitch to perform on-off switching so as to output a stable pressure difference switching signal to the outside.

The invention discloses a pre-charging control method, an energy storage device, electronic equipment and a storage medium. The pre-charging control method is applied to the energy storage device, the energy storage device comprises a plurality of pre-charging branches, and the pre-charging control method comprises the steps of obtaining a battery module voltage of a battery module and a device voltage of an external device; determining an equipment pre-charging branch according to the battery module voltage, the equipment voltage and the allowable voltage of each pre-charging branch; switching on an equipment pre-charging branch and timing, and acquiring a pre-charging voltage difference between the voltage of the battery module and the voltage of the equipment when the equipment pre-charging branch is switched on; and according to the timing duration and the pre-charging voltage difference, determining whether pre-charging is completed, and when pre-charging is completed, controlling the pre-charging branch circuit of the device to be switched off and controlling the charging and discharging branch circuit to be switched on. According to the embodiment of the invention, the pre-charging branch of the equipment is determined according to the voltage difference between the voltage of the battery module and the voltage of the equipment, the use requirements of users in different scenes are met, the pre-charging branch is prevented from being damaged, and the user experience is improved.

The present invention provides a charge pump circuit and an electronic device, wherein the circuit includes a voltage control module and a charge pump, wherein the voltage control module includes a comparison unit and a voltage control unit. The charge pump circuit is used to compare and process the boost voltage and the reference output voltage to obtain a first comparison signal, and to compare and process the first comparison signal with the floating ground voltage of the first node to obtain a second comparison signal; the first end of the voltage control unit receives the functional voltage, and the second end is coupled to the first node, and the first node is also grounded through a tail current source. The conduction degree of the voltage control unit is controlled by the second comparison signal to control the voltage of the first node, thereby controlling the voltage value of the floating ground voltage. The input end of the charge pump receives the functional voltage, and its ground end is coupled to the first node. The charge pump is used to boost the functional voltage and output the boost voltage. The rail voltage difference of the working voltage of the charge pump of the present invention is small, so that the voltage stress of the charge pump is small and the EMC performance is good.

Load sharing techniques for voltage regulators. In an example, the techniques may be implemented in an LDO voltage regulator configured to provide load sharing with a single driver for internal and external pass elements using a pair of variable voltage dividers to adjust the load sharing based on load current. In other examples, a calibrated voltage source can be used to replace one of the variable voltage dividers. Calibration circuitry and methodologies for determining the value of the calibrated voltage source are also described. In still other examples, a single variable voltage divider can be used, with no calibrated voltage source, by constraining the external pass element to be weaker than the internal pass element. In any such examples, the internal and external pass elements can be implemented, for instance, with either n-type or p-type power transistors, and with similar transistor technologies or diverse transistor technologies (e.g., FETs and BJTs).

The invention discloses a voltage coupling layered power flow regulation and control method based on a dual-core phase-shifting transformer, and relates to the technical field of power flow control of a power system, and the method comprises the steps: building a phase-shifting transformer amplitude relational expression based on a voltage prediction model, and dynamically outputting an optimal gear combination to eliminate a loop closing point voltage difference; a Thevenin equivalent model is introduced to predict a bypass impulse current constraint condition, and gear optimization and impulse current verification are completed before loop closing; taking the deviation minimization of the load side voltage and a rated value as an optimization target, and predicting a voltage change track by adopting an iterative optimization mechanism and combining with a local gear action set; voltage fluctuation threshold limitation in the exit strategy is fused into an iteration process, and an exit path is synchronously optimized in voltage regulation and control. According to the method, an iterative optimization mechanism and a voltage prediction model are adopted, large-range adjustment and high-precision control of the compensation voltage are achieved, the impact current risk of loop closing operation is reduced through synchronous optimization of a pre-regulation strategy and an exit path, and the continuity and stability of power grid operation are guaranteed.

The invention provides a linear voltage regulator, a parallel current sharing circuit and method thereof, and a display driving or touch sensing chip, a first circuit module and / or a second circuit module are / is arranged for a target linear voltage regulator connected in parallel, and when the current shared by the target linear voltage regulator exceeds a preset bearing range, the first circuit module and / or the second circuit module are / is connected with the first circuit module and / or the second circuit module. The first circuit module of the target linear voltage regulator can automatically limit the grid voltage of the output tube of the target linear voltage regulator not to be higher than the upper limit of a preset range, and the second circuit module of the target linear voltage regulator can automatically limit the grid voltage of the output tube of the target linear voltage regulator not to be lower than the lower limit of the preset range. By limiting the magnitude of the grid voltage of the output tube, the load current of the linear voltage regulator is limited within a certain range, so that the distribution of the load current among the linear voltage regulators connected in parallel is automatically adjusted, the voltage difference of the output voltage of the linear voltage regulators at different positions in a chip is prevented from being too large, and the reliability of the chip is improved. And the voltage drop of the output voltage on the wiring is prevented from being too large.

A method and device for determining a power supply voltage of a radio frequency power amplifier, a medium, and a communication device, the method comprising: determining a current environment, the current environment being selected from an alternative set, the alternative set comprising a first environment and a second environment, the noise of the first environment being less than the noise of the second environment; determining a power supply voltage of the radio frequency power amplifier in a receiving stage at least based on the current environment; wherein the power supply voltage difference in the first environment is smaller than the power supply voltage difference in the second environment, and the power supply voltage difference refers to the difference value of the power supply voltage of the radio frequency power amplifier in the sending stage and the power supply voltage of the radio frequency power amplifier in the receiving stage. Through the scheme provided by the invention, the power consumption of the radio frequency power amplifier can be reduced.

The invention provides a voltage difference monitoring device and method for a bootstrap switching power supply and the switching power supply. The device comprises a voltage difference detection module which is configured to detect the voltage difference between the two ends of a bootstrap capacitor and generate a lower tube conduction indication signal if the voltage difference does not reach a set threshold value; the lower tube forced conduction module is configured to generate a plurality of continuous pulse signals according to the lower tube conduction indication signal so as to conduct a lower transistor when the pulse signals are in high level, so that the bootstrap capacitor is charged through the first power supply voltage until the voltage difference reaches a set threshold value; and the negative current detection module is configured to send a forced turn-off signal to the lower transistor forced turn-on module and end the turn-on period, corresponding to the current pulse signal, of the lower transistor if a negative current greater than a threshold value is detected during the period of turning on the lower transistor through the pulse signal. According to the invention, high differential pressure detection precision is realized through a simple circuit structure.

An electronic device includes a first power management device configured to receive an input voltage, and output first voltages based on the input voltage, and at least one consumer which is configured to receive the first voltages from the first power management device, and operate based on the first voltages. The first power management device includes a switching regulator configured to generate a converted voltage from the input voltage, a first LDO regulator which is configured to generate a first output voltage from a first drop voltage generated by the converted voltage passed through a first PDN, a second LDO regulator and PDN, and a switching regulator which is configured to estimate a first dropout voltage of the first LDO regulator, calculate a voltage drop caused by the first PDN, and dynamically control the converted voltage based on estimated dropout voltages and calculated voltage drops caused by the PDNs.

The invention provides a low-dropout voltage stabilizing circuit without an off-chip capacitor, a chip and electronic equipment, the circuit comprises a low-dropout voltage stabilizing circuit and a transient response enhancement circuit, the low-dropout voltage stabilizing circuit is used for generating a first bias voltage and a second bias voltage and transmitting the first bias voltage and the second bias voltage to the transient response enhancement circuit; the reference circuit is also used for transmitting the reference voltage output by the reference circuit to the transient response enhancement circuit; and the transient response enhancement circuit is used for receiving the first bias voltage, the second bias voltage and the reference voltage, and when the reference voltage changes, the variable quantity is coupled to the low-dropout voltage stabilizing circuit, so that the low-dropout voltage stabilizing circuit adjusts the reference voltage output by the low-dropout voltage stabilizing circuit based on the variable quantity. The reference voltage is detected through the transient response enhancement circuit, when the reference voltage changes, the variable quantity is coupled to the low-dropout voltage stabilizing circuit to adjust the reference voltage, and the transient response speed of the LDO without the off-chip capacitor can be increased.

The utility model, which relates to the technical field of the LED, discloses a leakage protection circuit comprising a power supply circuit, a step-down circuit, an LED circuit and a detection circuit. The input end of the power supply circuit is connected to the output pin of the power supply end, the output end of the power supply circuit is connected with the input end of the step-down circuit and the input end of the LED circuit, and the power supply circuit is used for rectifying the output power supply of the power supply end so as to output the power supply to the step-down circuit and the LED circuit; the output end of the step-down circuit is connected with the detection circuit, and the step-down circuit is used for carrying out step-down processing on the power supply output by the power circuit to output reference voltage to the detection circuit; and the detection circuit is respectively connected with the output pins of the power supply end and the LED circuit, and is used for controlling the working state of the LED circuit according to the real-time voltage difference and the real-time voltage between the output pins of the power supply end and the reference voltage output by the step-down circuit. According to the utility model, the working state of the LED circuit can be controlled according to the real-time voltage difference, the real-time voltage and the reference voltage, thereby realizing anti-creeping protection.

The invention belongs to the technical field of integrated circuits, and particularly relates to a dynamic comparator suitable for a low-voltage high-speed analog-to-digital converter, the dynamic comparator adopts a three-stage latch circuit structure to realize rapid comparison of weak input signals so as to generate corresponding digital signals, and the method specifically comprises the following steps of: in a pre-amplification stage, pre-amplification is carried out; the positive feedback effect of the cross-coupled transistor pair is utilized to efficiently convert a tiny input voltage difference (lt; 10mV) into a recognizable voltage difference, and then through two-stage regeneration of the main latch module and the auxiliary latch module, a logic level is quickly output to complete quantization judgment. The auxiliary latch stage is additionally arranged on the basis of a traditional cross coupling latch circuit, the working speed of the comparator is effectively increased under the condition that only small area overhead is introduced, and the probability that the dynamic comparator has a metastable state is greatly reduced.

The invention discloses a control device, a computer readable storage medium, a power converter and a self-checking method thereof, and relates to the technical field of power electronics. According to the power converter, before a controller controls a Boost circuit to operate, a bus voltage is controlled to rise to a preset value, so that the negative electrode of a fly-wheel diode in the Boost circuit is higher than the positive electrode by a larger voltage difference; then, detecting whether the difference between the bus voltage and the input end voltage of the Boost circuit is smaller than or equal to a preset bearing threshold value or not; if the difference between the bus voltage and the voltage of the input end of the Boost circuit is smaller than or equal to a preset bearing threshold value, it is indicated that the fly-wheel diode cannot bear a large voltage difference between the two sides of the fly-wheel diode in a normal reverse cut-off state, and then it can be determined that the fly-wheel diode in the Boost circuit has a short-circuit fault. The method belongs to a pure software scheme, does not need to increase hardware cost, and does not increase the layout difficulty of a PCB and the size of equipment.

The invention discloses a multi-path power source redundant power supply control method and system, and belongs to the technical field of power electronics, the system comprises a dynamic priority decision module, a zero-voltage-drop switching circuit and a fault safety framework, the dynamic priority decision module supports a user to customize a power source use priority rule through an MCU, and the zero-voltage-drop switching circuit is used for switching the zero-voltage-drop switching circuit to the fault safety framework. The MCU can autonomously carry out an automatic degradation and upgrading mechanism through voltage quality; according to the zero-voltage-drop switching circuit, when the MCU detects a fault of the main power supply, a target power supply pre-charging path is started, and when the target power supply is pre-charged until the voltage difference between the target power supply and the source voltage is smaller than or equal to 0.1 V, the target power supply GaNFET can be synchronously triggered to be switched on, and the pre-charging circuit and the original power supply GaNFET can be synchronously triggered to be switched off. The multi-path power supply input automatic switching circuit solves the problems of power-off risk, easy conduction loss and relatively high failure rate in the prior art, is suitable for a multi-path power supply input automatic switching system of a decoder and industrial control equipment, and is particularly suitable for a long-time uninterrupted power supply condition.

The invention provides a surge suppression circuit applied to a switching power supply and the switching power supply, the surge suppression circuit comprises a first current limiting circuit, a second current limiting circuit and a main power switch which are connected in parallel, one end of the first current limiting circuit receives an input voltage, and the other end of the first current limiting circuit is coupled with a capacitor in the switching power supply; the voltage sampling circuit detects a voltage difference value between the input voltage and the voltage of the capacitor; the control circuit is used for controlling the main power switch to be switched off during cold start and controlling the main power switch to work in a closed state when the voltage difference value is smaller than a first voltage preset value; and after the input voltage is suddenly changed, the voltage difference level corresponding to the voltage difference value is judged, the controllable switch of the second current limiting circuit is controlled to be switched on when the voltage difference level is higher than a first preset level, and the controllable switch of the second current limiting circuit is controlled to be switched off and the main power switch works in an on state after the voltage difference value is reduced to a second voltage preset value. The circuit can effectively reduce the surge current in the switching power supply under different conditions, and is high in response speed.

According to the buffer output control circuit, the buffer output control method and the LDO circuit applying the buffer output control circuit, the second control signal generation circuit and the second transistor are arranged, and in the dropout state, the second control signal generation circuit generates the high-level second control signal based on the error amplification signal to control the second transistor to be switched on; the potential of the control end of the power tube is pulled down to the ground, the problem of voltage loss on the control end of the power tube in the prior art is avoided, the power tube can be completely conducted in the state, the output voltage changes along with the input voltage, the voltage difference between the output voltage and the input voltage is small, and then the system loss can be reduced; and compared with the prior art, the power tube with a smaller area can be adopted to realize the same technical index. When the output voltage is in a voltage stabilization state, the second control signal generation circuit generates a low-level second control signal based on the error amplification signal to control the second transistor to be turned off, namely, in the state, the buffer output control circuit does not affect the work of the power tube.