Dynamic Blanking Time Adjustment for Switch-Mode Power Supply Overload Protection
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Solution Overview
Problem
Switch-mode power supply controllers face challenges in effectively managing overload protection, particularly in avoiding mistriggering due to noise, and require improved methods to determine the end of a fault condition and adjust blanking times accordingly.
Innovation Solution
A method and device that utilize a first and second blanking time interval, where the first interval measures the time to charge the feedback voltage and stores a timer setting time, and the second interval performs a charge cycle sequence based on this setting, incrementing a counter if the voltage threshold is reached within the timer setting time, and initiating a shutdown mode if the counter reaches a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed blanking time is used for overload protection, then the system can protect against overload conditions, but the system may mistrigger due to noise or fail to adapt to different fault conditions
Solution Approach 1:
The patent implements dynamic blanking time adjustment by measuring the actual feedback voltage charging time and using this measured value to set the blanking time period. Instead of using a fixed predetermined blanking time, the system adapts the blanking duration based on real-time electrical characteristics, allowing optimal protection for different fault conditions while reducing false triggering.
Solution Approach 2:
The system changes the blanking time parameter dynamically by measuring the feedback voltage charging time and storing this measured time as the basis for the blanking period. This parameter adjustment enables the system to optimize protection accuracy for various overload scenarios rather than using a static time value.
2Reliability
If the blanking time is extended to avoid noise triggering, then mistriggering is reduced, but the response time to actual fault conditions is delayed
Solution Approach 1:
The system uses its own feedback voltage charging characteristics to automatically determine the appropriate blanking time. By measuring how long it takes for the feedback voltage to charge under normal conditions, the system self-configures an optimal blanking period that provides noise immunity without excessive delay, eliminating the need for external configuration or compromise.
3Measurement precision
If multiple charge cycles are performed to confirm fault end, then the accuracy of fault detection is improved, but the complexity of the control circuit increases
Solution Approach 1:
The feedback pin and associated circuitry serve multiple functions: normal voltage regulation feedback, fault detection, and blanking time measurement. By making the feedback circuit multi-functional, the patent achieves accurate fault detection through multiple charge cycle verification without adding separate dedicated circuits, thus minimizing complexity increase.
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 enhances the accuracy of overload protection by determining the end of a fault condition and adjusting the blanking time, reducing the risk of mistriggering and allowing for stable output voltage regulation.
Implementation Method 1
During the first blanking time interval, the time to charge the feedback voltage at the feedback input of the switch-mode power supply is measured
Data Source
AI summary
A blanking time for a switch-mode power supply controller includes a first blanking time interval and a second blanking time interval. During the first blanking time interval, the time to charge the feedback voltage at the feedback input of the switch-mode power supply is measured, and a timer setting time is stored based on the measured time. During the second time interval, a series of charge cycles is used. At each charge cycle, the feedback voltage is discharged and then allowed to charge. If, after being discharged, the feedback voltage reaches a voltage threshold during the timer setting time, a counter value is incremented and the next cycle begins. If the feedback voltage does not reach the voltage threshold within the timer setting time, the blanking time ends. If the counter value reaches a count threshold, a shutdown mode is initiated.