SMPS Single Terminal Protection Circuit
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Solution Overview
Problem
Conventional switching mode power supplies (SMPS) require additional terminals for current sensing and feedback information, increasing complexity and cost, while existing protection circuits struggle to effectively distinguish between different protection operation conditions.
Innovation Solution
A simplified SMPS configuration that uses a single terminal to receive current sensing and feedback information, with a switching controller performing protection operations based on a reference voltage maintained for a predetermined time period, reducing the number of terminals and enhancing protection functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional terminals are used for current sensing and feedback information, then the protection circuit can distinguish different protection operation conditions, but the number of elements increases complexity and cost
Solution Approach 1:
The patent combines current sensing information and feedback information into a single terminal (CS/FB terminal). The switching controller multiplexes this single terminal to receive both types of information at different times, eliminating the need for separate terminals and reducing overall device complexity while maintaining protection functionality.
Solution Approach 2:
The single CS/FB terminal serves multiple functions: it acts as both a current sensing terminal and a feedback terminal depending on the operational phase. The switching controller universally uses this terminal for different purposes during different switching cycles, reducing the total number of terminals required.
2Reliability
If two current sources with different current levels are used to distinguish protection operation conditions, then long and short protection conditions can be distinguished, but the number of elements increases
Solution Approach 1:
The switching controller uses periodic switching actions to generate different voltage levels at the single terminal during different phases of the switching cycle. By periodically varying the duty cycle and timing, the controller creates distinct voltage patterns that indicate different protection conditions without requiring multiple physical current sources.
Solution Approach 2:
The patent changes electrical parameters (voltage level, pulse width, frequency) of the signal at the single terminal to encode different protection condition information. Instead of using multiple current sources with different current levels, the controller modulates the parameters of a single signal to convey multiple states.
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
This approach simplifies the SMPS design by reducing terminal count, enhances protection operation efficiency, and maintains system security against overloads, short circuits, and open loops without increasing complexity or cost.
Implementation Method 1
a main switch coupled to a primary coil of a transformer, and supplying power to a secondary coil of the transformer according to an operation by the main switch
Data Source
AI summary
A switching mode power supply and a corresponding method of protection operation is presented. A switching controller of the switching mode power supply receives current sensing information corresponding to the current flowing through a main switch and feedback information corresponding to an output voltage through a single terminal, and performs a protection operation when the voltage at the terminal is maintained to be lower than a reference voltage for more than a predetermined time frame. The power supply requires a low number of terminals, while preserving the protection operation function.