Over Current Protection Circuit Integrating Soft Start Cell
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Solution Overview
Problem
Conventional power converters require additional soft start circuits for over current protection, leading to complex circuits and increased area occupation.
Innovation Solution
An over current protection circuit with a soft start cell and operational amplifier that progressively increases the duty cycle of the driving signal during the soft start interval, eliminating the need for an additional soft start circuit and simplifying the design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an additional soft start circuit is added to achieve soft start function, then the soft start function is improved, but the device complexity increases
Solution Approach 1:
The patent merges the soft start function with the existing over current protection circuit by integrating a soft start cell into the operational amplifier structure. The soft start cell includes a capacitor and transistor that work together with the current sensing circuit to progressively increase the duty cycle during startup, eliminating the need for a separate soft start circuit while maintaining both soft start and over current protection functions in a unified circuit architecture.
2Adaptability or versatility
If an additional soft start circuit is added to achieve soft start function, then the soft start function is improved, but the area occupation increases
Solution Approach 1:
The soft start function is merged into the existing over current protection circuit, sharing common components such as the operational amplifier, current sensing circuit, and feedback control circuit. This integration eliminates redundant components and reduces the overall circuit area while providing both soft start and over current protection functions.
Solution Approach 2:
The operational amplifier and associated circuitry are designed to perform multiple functions: over current protection, soft start control, and feedback regulation. The soft start cell integrates with the current sensing circuit to progressively adjust the duty cycle, making the same circuit components serve both protective and startup functions simultaneously, thereby reducing area occupation.
3Adaptability or versatility
If the duty cycle signal is modified to vary from short to long, then the soft start function is achieved, but the device complexity increases
Solution Approach 1:
The soft start cell is configured to preliminarily control the duty cycle signal during the startup phase. A capacitor in the soft start cell is gradually charged through a transistor, creating a time-dependent voltage that progressively increases the duty cycle from short to long. This preliminary action achieves soft start functionality through passive component charging behavior rather than complex active control circuitry.
Data Source
AI summary
An over current protection circuit and a power converter using the same. The over current protection circuit includes a soft start cell and an operational amplifier. The soft start cell outputs a soft start signal according to a direct current (DC) level, and the soft start signal increases progressively to the DC level in a soft start interval. The operational amplifier outputs an over current signal to a feedback control circuit according to the soft start signal and an inductance current of a switching converter so that a duty cycle of a driving signal from the feedback control circuit increases progressively in the soft start interval.