Trigger Circuit for Switched-Mode Power Supply
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Solution Overview
Problem
Existing switching power supplies face challenges in achieving efficient regulation with complex and costly components, requiring tight tolerances for electronic components to maintain necessary regulating accuracies.
Innovation Solution
A trigger circuit that detects demagnetization on the supply voltage regulation input or peak current detection input, using resistors and capacitors to superimpose signals, allowing for reduced component complexity and wider tolerances, enabling output current and voltage limitation, and overvoltage protection, while being housed in a 3-pin or 4-pin configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional separate auxiliary winding detection method is used, then demagnetization detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the demagnetization detection function with existing circuit nodes (supply voltage regulation input or peak current detection input) by superimposing the detection signal through resistors and capacitors. This merging approach eliminates the need for separate dedicated detection circuits while maintaining detection functionality, thereby reducing device complexity without sacrificing measurement precision.
Solution Approach 2:
The existing supply voltage regulation input or peak current detection input is made multi-functional by superimposing the demagnetization detection signal onto it. This allows the same circuit node to serve both its original function and the additional demagnetization detection function, reducing overall circuit complexity while maintaining accurate detection capabilities.
2Measurement precision
If tight tolerances are required for electronic components, then regulating accuracy is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The circuit uses the existing operational characteristics of the supply voltage regulation input or peak current detection input to perform demagnetization detection. By leveraging the self-service capability of existing circuits and their inherent tolerance characteristics, the patent achieves accurate regulation without imposing stringent additional tolerance requirements on external components, thereby easing manufacturing constraints.
3Device complexity
If output current depends on internal timing elements, then circuit simplicity is maintained, but regulation flexibility and precision are reduced
Solution Approach 1:
The patent implements feedback by detecting demagnetization through the supply voltage regulation input or peak current detection input, which provides information about the actual transformer state. This feedback mechanism allows the output current to be regulated based on actual operational conditions rather than solely on internal timing elements, improving regulation flexibility and precision while maintaining reasonable circuit simplicity through the use of passive components for signal superimposition.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides improved regulation characteristics, increased flexibility, and reduced costs by making the output current independent of internal timing elements, with precise current and voltage regulation, and simplified zero-crossing detection, thus minimizing structural height and operational losses.
Implementation Method 1
an additional, primary-side auxiliary winding is arranged on the transducer, wherein an indicated voltage is generated by this auxiliary winding
Implementation Method 2
A signal required for detecting the demagnetization is then superimposed on the voltage on the supply voltage input or the peak current detection input. This can be realized in a simple way by means of one or more resistors and/or capacitors.
Data Source
AI summary
The present invention relates to a trigger circuit for a switch in a switching power supply, especially in a primary-side, triggered switching power supply. The trigger circuit here comprises a feedback signal terminal for detecting an auxiliary voltage induced on a primary-side auxiliary winding of a transformer of the switching power supply, a supply voltage terminal for supplying the trigger circuit with a supply voltage, and a ground terminal for connecting the trigger circuit to a ground potential, wherein the feedback signal terminal is formed by the supply voltage terminal and the auxiliary voltage is superimposed on the supply voltage. Alternatively, the voltage of the auxiliary winding could be superimposed on the voltage on an additional pin that is used for detecting the primary peak current.