Short Circuit Protection Logic for Transient Filtering
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Solution Overview
Problem
Existing short circuit protection systems in power path devices often incorrectly trigger due to supply transients, leading to unwanted power interruptions and system downtime, as they fail to differentiate between transient events and actual short circuits.
Innovation Solution
The implementation of a system that monitors both current and voltage levels to differentiate between supply transients and short circuits, using an output voltage fall detector and current increase detector to determine if the voltage is increasing or decreasing, thereby enabling or disabling scalable short circuit protection accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If short circuit protection is enabled to protect against actual short circuits, then system reliability is improved, but false triggering during supply transients causes unwanted power interruptions and system downtime
Solution Approach 1:
The protection system dynamically adjusts its sensitivity and triggering behavior based on real-time voltage conditions. During supply transients when voltage is rising, the system disables or reduces short circuit protection sensitivity. During normal operation when voltage is stable or falling, the system enables full protection. This dynamic adaptation allows the system to maintain high reliability during actual short circuits while avoiding false triggering during transient events, thereby reducing unnecessary system downtime.
Solution Approach 2:
The system changes the operational parameters of the short circuit protection based on the detected voltage trend. When an increasing voltage condition (supply transient) is detected, the protection threshold or enabling signal is modified to prevent false triggering. When a falling voltage condition (actual short circuit) is detected, the protection is activated at normal sensitivity. This parameter change approach allows the same protection circuit to operate in two distinct modes, resolving the contradiction between over-protection during transients and under-protection during actual faults.
2Speed
If short circuit protection triggers immediately upon current increase, then protection response speed is improved, but it cannot differentiate between transient events and actual short circuits leading to false interruptions
Solution Approach 1:
The system introduces voltage trend detection as an intermediary condition between current increase detection and protection triggering. Instead of directly triggering protection upon current increase, the system first checks the voltage condition (rising or falling). This intermediary voltage monitoring mechanism allows the system to maintain fast response to actual short circuits (when voltage falls with current increase) while filtering out transient events (when voltage rises with current increase). The intermediary voltage check provides the differentiation capability without significantly delaying the protection response time.
Solution Approach 2:
The system performs preliminary voltage trend detection before finalizing the protection trigger decision. By monitoring voltage conditions in advance and using this information to modulate the protection triggering, the system can prepare the protection mechanism to respond appropriately. When voltage is rising, the preliminary detection prevents the protection from triggering even if current increases. When voltage is falling, the preliminary detection ensures rapid triggering. This preliminary action approach maintains fast response while improving detection accuracy.
Data Source
AI summary
Methods, apparatus, systems and articles of manufacture are disclosed for preventing undesired triggering of short circuit or over current protection. An example apparatus includes an output terminal; a voltage detection device coupled to a voltage detection input terminal and the output terminal and including a voltage detection output coupled to a logic gate first input terminal; a pulse extender coupled between a logic gate output and a selecting node; a multiplexer coupled to the selecting node and configured to be coupled to a first protection circuit, a second protection circuit, and a driver; and a switch coupled between an input terminal and the output terminal and including a switch gate terminal coupled to the driver.