Soft Start Circuit Using Residual Voltage Comparison
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional soft start circuits either require releasing residual voltage, necessitating extra components or are limited to specific converter types, leading to inefficiencies and increased power consumption.
Innovation Solution
A method and circuit that monitor the output voltage's feedback signal and compare it with a ramp signal to enable the system only when the ramp signal reaches the feedback signal, allowing the output voltage to rise from residual voltage to a target level without releasing the residual voltage or requiring additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conventional soft start circuit releases residual charges on the output to pull down the output voltage, then the feedback signal becomes lower than the ramp signal enabling the converter, but the residual charges are wasted and power consumption increases
Solution Approach 1:
The patent converts the harmful effect of residual charges (which cause feedback signal to be higher than ramp signal and prevent converter startup) into a beneficial feature by using the residual voltage as the starting point for soft start. The comparator directly compares feedback signal with ramp signal, and when feedback > ramp, the converter is already enabled, allowing the system to utilize existing residual voltage rather than wasting it.
2Loss of energy
If the conventional soft start circuit uses an extra capacitor to charge by residual charges before enabling the converter, then the converter can start without releasing residual voltage, but additional components are required and the ramp signal is an RC discharge curve which is disadvantageous to soft start performance
Solution Approach 1:
The patent extracts and removes the unnecessary extra capacitor component from the circuit. Instead of using an RC discharge curve through an additional capacitor, the invention directly uses the existing feedback signal from the output voltage and compares it with the ramp signal through a comparator, simplifying the circuit while maintaining the ability to utilize residual charges.
Solution Approach 2:
The patent makes the soft start circuit universally applicable to various converter types by using a general-purpose comparator that can handle any feedback signal configuration. The circuit doesn't rely on specific converter topology or require additional components, making it adaptable to different applications.
3Reliability
If the conventional soft start circuit is designed for specific converter types, then the soft start function can be implemented, but the applicability is limited and cannot be used with other converter types
Solution Approach 1:
The patent achieves universal applicability by using a simple comparator-based approach that works with any converter type having a feedback signal. The circuit monitors the output voltage through the feedback signal and compares it with a ramp signal, a method that can be applied to buck converters, boost converters, and other converter topologies without modification.
Data Source
AI summary
A circuit and method for soft start of a system compare a feedback signal produced from an output voltage of the system with a ramp signal to generate a comparison signal, and enables the system once the comparison signal indicating the ramp signal reaches the feedback signal, such that the output voltage becomes active from a residual voltage toward a target level.