Switching Mode Power Supply Over Voltage Protection Using Multi-Function Controller
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Solution Overview
Problem
Existing over voltage protection mechanisms in switching mode power supplies are inaccurate due to inductor leakage, and they often require additional components like Zener diodes and photo-couplers, increasing cost and product size.
Innovation Solution
A power supply design that includes a transformer with a primary and auxiliary winding, a power switch, a sensing resistor, and a controller with a multi-function terminal that detects current and voltage, triggering a protection mechanism only when the voltage exceeds a reference after a delay to account for inductor leakage without additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional over voltage protection mechanisms are used, then protection function is provided, but measurement precision deteriorates due to inductor leakage
Solution Approach 1:
The patent applies preliminary action by introducing a delay mechanism that waits for the inductor current to fully discharge before performing voltage detection. This timing-based approach proactively accounts for the inductor leakage issue by ensuring detection only occurs after the leakage has naturally ceased, thereby maintaining both protection reliability and measurement precision without requiring additional hardware components.
2Reliability
If Zener diode and photo-coupler are added for over voltage protection, then protection reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by enabling the CS terminal to serve dual functions: both current sensing during the power switch on-state and over-voltage detection during the off-state. This multi-functional approach eliminates the need for separate protection components like Zener diodes and photo-couplers, reducing device complexity while maintaining protection reliability through intelligent terminal utilization.
Solution Approach 2:
The patent applies self-service by utilizing the existing controller and CS terminal infrastructure to provide over-voltage protection without requiring external dedicated protection components. The system leverages its own built-in resources (controller, multi-function terminal, existing circuitry) to achieve protection functionality, thereby simplifying the overall device structure while ensuring reliable operation.
3Reliability
If additional protection components are added, then protection capability is enhanced, but product size increases
Solution Approach 1:
The patent applies universality by making the CS terminal multi-functional, serving both as a current sensing input during the power switch on-state and as an over-voltage detection input during the off-state. This eliminates the need for additional external protection components that would increase product size, while maintaining robust protection capability through intelligent reuse of existing circuit resources.
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 solution provides accurate over voltage protection in switching mode power supplies by eliminating inaccuracies caused by inductor leakage and reducing component costs and size, ensuring reliable operation.
Implementation Method 1
The diode and the first resistor are coupled between the auxiliary winding and the multi-function terminal
Implementation Method 2
when the power switch is turned off, the controller detects a voltage of the multi-function terminal, and determines to trigger a protection mechanism if the voltage of the multi-function terminal is over a reference voltage
Data Source
AI summary
Power supplies together with related over voltage protection methods and apparatuses. A power supply has a transformer including a primary winding and an auxiliary winding. A power switch is coupled to the primary winding and a sensing resistor coupled between the power switch and a grounding line. A multi-function terminal of a controller is coupled to the sensing resistor. A diode and a first resistor is coupled between the auxiliary winding and the multi-function terminal.