Switching power supply circuit with precise voltage abnormality protection and method

Abstract

The invention provides a switching power supply circuit with precise voltage abnormality protection and method. The switching power supply circuit comprises a rectifier circuit with AC inputted, a driving circuit connected with the output end of the rectifier circuit and an output filter circuit connected to the output end of the driving circuit. The switching power supply circuit and the method have the beneficial effects that input voltage undervoltage detection, input voltage overvoltage detection, and output overvoltage detection have cycle-by-cycle detection capability according to the operating frequency of the switching power supply system; an anti-jitter time shielding function is achieved; when instantaneous voltage exceeds a set range due to interference or jitter, the power supply can shield instant abnormal voltage detection signals through delay judgment, the control circuit does not perform a protection action; and when the detected abnormal signals exist for a certain period of time, the control circuit performs the protection action, and when the switching power supply is started or closed for protection and restarted, input voltage undervoltage point detection andinput voltage overvoltage point detection have a hysteresis function.

Description

technical field [0001] The invention relates to the technical field of switching power supplies, in particular to a switching power supply circuit and method with precise voltage abnormality protection. Background technique [0002] The flyback switching power supply is a commonly used power supply device, and the flyback switching power supply is used in many occasions. In some countries and regions with underdeveloped power grids, the input AC power of power supply equipment fluctuates too much, and even the input voltage exceeds the voltage limit that the switching power supply can withstand, or working at a lower input voltage will lead to low efficiency and high temperature rise. Component life, or even damage. In addition, if the output DC voltage provided by the switching power supply to the load is abnormally increased due to damage to components and other reasons, the output voltage exceeds the allowable range, and the load equipment may be damaged. The traditiona...

AI Technical Summary

Problems solved by technology

The obvious disadvantages of this protection circuit are: the resistance voltage divider sampling circuit brings loss, which significantly increases the standby power consumption; the input mains voltage divider resistor affects PCB wiring, and occupies the PCB area, increasing the cost; a separate input voltage detection is required Chip pins, which affect chip pin integration and system cost

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