Primary side feedback (FB) switching power supply controller and switching power supply system

Abstract

The invention relates to a primary side feedback (FB) switching power supply controller and a switching power supply system. The switching power supply system comprises a transformer, a voltage-dividing circuit, a main switch tube, an output circuit and the primary side FB switching power supply controller, wherein the voltage-dividing circuit is connected to the transformer; the power supply endof the primary side FB switching power supply controller is connected with the primary side first input end of the transformer; the FB control end of the primary side FB switching power supply controller is connected to the voltage-dividing point of the voltage-dividing circuit; the input end of the primary side FB switching power supply controller is connected with the grid of the main switch tube; the control end of the primary side FB switching power supply controller is connected to the source of the main switch tube; and the primary side FB switching power supply controller comprises an FB waveform detection module, a triangular wave generating circuit, a first comparer, a narrow pulse generating circuit, a second comparer and an RS (Reset-Set) trigger. Due to the implementation of the primary side FB switching power supply controller and the switching power supply system, provided by the invention, the system stability can be effectively improved, the complexity of a peripheral system can be lowered, the quantity of peripheral elements can be reduced, and the cost of a product can be reduced.

Description

technical field [0001] The invention relates to the field of switching power supplies, more specifically, to a primary side feedback switching power supply controller and a switching power supply system. Background technique [0002] AC / DC converters for converting high-voltage alternating current to low-voltage direct current required by the load have been developed quite maturely. For safety requirements, it is necessary to isolate the input and output through a transformer. Usually, it is necessary to use an optocoupler to feed back the information of the output voltage to the controller on the primary side, and the controller adjusts the output voltage according to the feedback information. However, the controller on the primary side still cannot detect the output current information and make appropriate adjustments. In recent years, more and more attention has been paid to the constant current and constant voltage technology that uses the primary side feedback technol...

AI Technical Summary

Problems solved by technology

[0006] figure 2 Both the current control loop and the voltage control loop of the controller shown require complex compensation circuits to ensure the system works stably under various operating conditions, thus increasing the production cost, the complexity of the peripheral system and the number of peripheral components

In addition, for the controller itself, since the constant voltage and constant current control loops are almost independently designed in the chip, there are fewer shared circuit modules, and the utilization rate of the device is low, which increases the chip area of ​​the controller and increases the production cost.

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