Switching Regulator Control Circuit for Output Short-Circuit Protection
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Solution Overview
Problem
Conventional switching regulator control circuits fail to respond quickly to output short-circuit conditions, leading to potential damage due to excessive current, as they are designed for general over current conditions and not specifically for short-circuit scenarios.
Innovation Solution
A switching regulator control circuit with an over current judgment circuit, a time comparison circuit, and a timer that distinguishes between mild over current and output short-circuit conditions by using different time periods for protection signals, allowing for immediate response to short-circuit conditions without complex circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional over current protection mechanism is used to compare circuit current with a predetermined upper limit and count the time period, then the circuit can protect against general over current conditions, but it cannot respond in time to output short-circuit conditions which generate very large current within a very short time
Solution Approach 1:
The protection mechanism is segmented into two distinct pathways: a first time period counter for general over-current conditions and a second time period counter for short-circuit conditions. This segmentation allows the system to handle different protection scenarios with appropriately tuned response times, enabling both reliable general protection and rapid short-circuit response.
Solution Approach 2:
The system dynamically switches between different time period settings based on the detected over-current condition. When a short-circuit is detected (current exceeding threshold within a predetermined time), the system activates a shorter second time period for rapid protection, otherwise it uses the longer first time period for general over-current conditions. This dynamic adaptation resolves the contradiction between response speed and protection reliability.
2Reliability
If the timer counts a longer first time period for general over current conditions, then the protection is appropriate for mild conditions, but it delays the protection response for severe short-circuit conditions
Solution Approach 1:
The timer dynamically adjusts its counting duration based on the severity of the detected condition. For mild over-current conditions, it counts the longer first time period to avoid false protection. For severe short-circuit conditions, it switches to counting the shorter second time period, eliminating unnecessary delay and enabling rapid protection while maintaining appropriateness for both scenarios.
Solution Approach 2:
The system changes the time parameter (counting duration) based on the detected condition severity. By switching between a first time period value for general conditions and a second time period value for short-circuits, the system optimizes both protection appropriateness and response timing, resolving the contradiction between these two requirements.
3Device complexity
If the circuit uses a single time period for all over current conditions, then the circuit design is simple, but it cannot provide optimized protection for different severity levels of current abnormalities
Solution Approach 1:
The protection circuit is segmented into distinct functional blocks: an over-current detection unit, a time period selection unit, and a timer unit. This modular segmentation enables the circuit to handle multiple protection scenarios with different time periods while maintaining relatively simple individual component designs, thus achieving both simplicity and adaptability.
Solution Approach 2:
The timer unit is designed with multi-functionality, capable of counting both the first time period for general over-current conditions and the second time period for short-circuit conditions. This universal timer design eliminates the need for separate timers for each condition, maintaining circuit simplicity while providing adapted protection for different severity levels.
Data Source
AI summary
The present invention discloses a switching regulator control circuit which distinguishes the output short-circuit condition, which imposes immediate danger, from other mild over current conditions. The switching regulator control circuit includes: an over current judgment circuit comparing a current sense signal with a current limit to generate an over current indication signal; a time comparison circuit comparing the over current indication signal with a clock signal to generate an output short-circuit indication signal; and a timer receiving the over current indication signal and the output short-circuit indication signal, wherein when the output short-circuit indication signal does not indicate output short-circuit, the timer counts a first time period, and when the output short-circuit indication signal indicates output short-circuit, the timer counts a second time period shorter than the first time period, for better safety protection.